How Much Fibre Should You Eat?

How much fibre should you eat? As with most things to do with the diet, there is a lot of misinformation and confusion about what your fibre intake should be. The goal of this article is to clear up the confusion, and help you better understand fibre and how much you should be consuming. 

But I don’t want to just give you an un-contextualised answer. I want to give you the information you need to actually be able to tailor your fibre intake specifically to your needs (or the needs of your clients, as I know a lot of personal trainers, coaches and nutritionists read our content).

This article is still a part of the larger article series on how to set up the diet. So far in that article series, we have discussed setting up the calories for the diet, how much protein should you eat, how much fat should you eat, how much carbohydrate you should eat and now we turn our attention to fibre intake.

Often fibre isn’t included in discussions of the macronutrients, but it is a nutrient that must be consumed in macro quantities, and it does actually play a role in the diet. So I tend to treat it like the other macronutrients too.

However, it does technically fall under the umbrella category of carbohydrates, so it is understandable why some people don’t treat it as a macronutrient in its own right. But hopefully, by the end of this article, you will understand why fibre is important to consume in the diet and how much you should be consuming.

Before we get stuck in, I would just like to remind you that we offer comprehensive online coaching. So if you need help with your own exercise program or nutrition, don’t hesitate to reach out. If you are a coach (or aspiring coach) and want to learn how to coach nutrition, then consider signing up to our Nutrition Coach Certification course. We do also have an exercise program design course in the works, if you are a coach who wants to learn more about effective program design and how to coach it. We do have other courses available too.

Understanding Fibre

While we discussed carbohydrates in the last article, we have actually ignored a segment of carbohydrates; fibre. Unfortunately, there is some debate over what exactly fibre is. All the definitions of what fibre is are pretty similar, but also somewhat different. 

The basic definition seems to be that fibre is the component of carbohydrates that the human digestive tract can’t digest. 

While we do often think of fibre as being purely plant-based in origin, that isn’t necessarily true. I know it is somewhat strange to try and dissociate the two (plants and fibre), however, it does actually lead to a better understanding of human nutrition on the whole. 

There are many foods that are not plant-based but do actually contain fibre. For example, milk contains fibre (undigestible oligosaccharides), despite not being plant-based in origin. 

If you think of fibre in purely a plant-based way, you do run the risk of overlooking sources of fibre in the diet. It is far better to look at fibre as a component of carbohydrate sources, rather than solely as a component of plants. 

It is very visual to think of fibre as the roughage part of plants and to imagine actual fibrous, almost woody components, however, fibre includes much more than this when you consider it in the broader context of carbohydrates that humans can’t digest.

There are many different identified fibres, such as arabinoxylans, cellulose, resistant starch, resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and indigestible oligosaccharides. So you will potentially see fibre written as many different things when reading about nutrition, and each of these will have different properties and effects on the body. 

For a general discussion of fibre, most people will just broadly categorise them as either soluble or insoluble fibre, and this is as good as any broad categorisation. While you will find exceptions to the generalisations, it certainly does make understanding fibre quick and easy.

Soluble fibre is the fibre that can be dissolved in water. This type of fibre is easily fermented in the large intestines. The fermentation results in both gases and potentially physiologically active byproducts.

Insoluble fibre is the fibre that can not be dissolved in water. It is generally considered to be inert and is quite often only discussed in its role of providing bulk to stools. It provides bulk to stools because it is insoluble and undigestible and thus has to pass through the digestive system somewhat intact, thus it takes up space (provides bulk). However, it also pulls in water as it passes through the digestive tract, so this further bulks stools, and eases defecation. While it is often ignored when discussing insoluble fibres, they can also be fermented to some extent in the large intestines.

So, essentially, fibre is the part of naturally occurring carbohydrates that we don’t digest in the small intestines, and is instead, handled by the large intestines, or passed out completely “undigested”. Now, while it is all well and good to discuss what exactly fibre is, and we could sit here all day discussing it, it doesn’t really help your overall understanding of nutritional practices. 

However, discussing fibre digestion and its role in the body will improve your understanding, and we can then make more informed decisions about our fibre recommendations.

Fibre Digestion

Now, if fibre can’t be digested, you would be forgiven for thinking that it doesn’t really contribute much to the diet overall, and can be disregarded. However, you would be wrong. 

You see, while humans can’t digest fibre, the bacteria in our guts can digest fibre. Fibre is digested (fermented) by gut bacteria, and this does actually provide some caloric value to humans. 

The process of fibre digestion is relatively straightforward, although it does actually tie together quite a few aspects of digestion overall. I find thinking about what happens step by step in the digestive tract to be quite helpful in understanding what is happening with fibre digestion.

1. Ingestion: Fibre enters the digestive system when you consume foods that contain fibre, mainly via foods such as fruits, vegetables, whole grains, legumes, and nuts.
2. Mouth: Some initial mechanical breakdown of fibre occurs in the mouth through chewing and mixing with saliva. However, unlike other carbohydrates, fibre does not get broken down by enzymes in saliva or the mouth.
3. Stomach: Fibre continues to move into the stomach. Here, it does not undergo significant digestion, as the stomach primarily breaks down proteins with the help of stomach acid and digestive enzymes.
4. Small Intestine: The small intestine is where most nutrient absorption takes place in the digestive system. However, fibre passes through the small intestine mostly unchanged. It doesn’t provide calories or nutrients like proteins, carbohydrates, or fats do. However, some soluble fibre, like pectin and gums, can absorb water and form a gel-like substance, which can slow down the absorption of other nutrients and glucose.
5. Large Intestine (Colon): The majority of fibre reaches the large intestine (colon) largely intact. Here, two main types of fibre have distinct effects:
   • Soluble Fibre: This type of fibre dissolves in water to form a gel-like substance, and can slow digestion and absorption. Bacteria in the colon can ferment some soluble fibres, producing short-chain fatty acids (SCFAs), which can have various health benefits.
   • Insoluble Fibre: This type of fibre does not dissolve in water. Instead, it adds bulk to the stool and helps prevent constipation by promoting regular bowel movements. Insoluble fibre can also help maintain the health of the intestinal lining.
6. Fermentation: Some types of fibre, particularly soluble fibre, are fermented by bacteria in the large intestines. This fermentation process produces gases (such as carbon dioxide, methane, and hydrogen) and short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate. SCFAs are a valuable energy source for the colon cells and play a role in maintaining gut health. This fermentation process is largely what is responsible for flatulence (although there are other contributors, such as swallowed air).
7. Elimination: Ultimately, fibre, along with the other indigestible components of the diet, forms the bulk of stool. It adds softness and bulk to the stool, making it easier to pass during bowel movements.

But there is actually more going on than this, and we can expand our understanding a little bit more.

If you eat carbohydrates, the majority of them get digested and assimilated in the small intestines. However, let’s assume that included within the carbohydrates you ate are some undigestible carbohydrates (fibre). 

The food you eat gets combined with bile so as to digest fats. Well, this bile also combines with fibre, and then gets pulled through the digestive tract and then excreted in your stool. Bile is synthesised from cholesterol, and is usually recycled rather than excreted. However, fibre can serve to remove this bile and thus, it can play a role in reducing cholesterol in the body. This has important implications for the health effects of fibre, as we will discuss later.

Most of the food you eat gets digested and absorbed in the small intestines. However, despite the body’s carbohydrate digesting enzymes being secreted and mixed with the food here, fibre resists digestion and as such, continues on through to the large intestines. This is where fibre digestion occurs. 

The bacterial populations of the large intestines (often called the gut microbiome) are able to break down the fibre that you aren’t able to digest. They do this anaerobically (without oxygen), and in doing so, they produce gases (such as hydrogen, carbon dioxide and methane) and also short-chain fatty acids (such as acetate, propionate and butyrate). 

These gases are either absorbed and then secreted through sweating or breathing, or they are released via the anus (flatulence). The fatty acids are also absorbed by the cells of the large intestines. Butyrate is mainly used by the cells of the large intestines, while acetate is absorbed into the blood and then taken up by the liver, muscles and various other tissues. Propionate is a precursor of glucose for some animals, but this hasn’t been shown in humans. Anything that isn’t able to be digested by the gut bacteria, along with any unused byproducts of this digestion, is excreted via the anus.

So fibre digestion doesn’t actually happen by human means, but it does occur to some extent by the bacterial populations we house in our large intestines. This naturally means that these bacterial populations are important for human digestion. 

Now that you have a basic understanding of what fibre is and how fibre digestion occurs, we need to discuss the role of fibre in the body.

The Role Of Fibre

I know that fibre is commonly thought of as not really contributing much to the diet, but this really is an incorrect way of thinking. However, much like carbohydrates, there is no “essential fibre”, and thus your intake could technically be zero. So, if you are to understand how much fibre you should eat, we have to discuss the role of fibre in the body. Understanding this really will help you to make much better decisions about how much fibre you should eat. 

Fibre plays an important role in the overall digestive process, and that is one of the main things people will say when you ask what they know about fibre’s role. The most common answer will be “it helps you poop”. However, fibre does much more than just help keep you regular. 

High-fibre diets have been linked with many positive health outcomes, including weight loss and cancer prevention. Which is pretty cool considering fibre is not technically digested by humans. Something you eat, that you can’t digest, results in many health benefits. 

Fibre is a part of most people’s diet, yet most people’s understanding of fibre is quite lacklustre. They have likely heard all kinds of benefits to fibre intake helping with their bathroom habits, but that is generally the extent of what people understand of fibre. 

So, let’s discuss some of the roles of fibre, and hopefully show you why it is something you should be thinking about when designing your diet.

Calories

The first thing to consider when discussing fibre’s roles is, naturally enough, its calorie contribution. While fibre is often considered to be a “zero” calorie nutrient, this is not actually true. Fibre does contain calories despite what some people and companies (usually those selling “0 carb”/“negative calorie”/“low calorie” foodstuffs) say. 

Fibre is largely undigested but it does provide some calories to the body, with the exact amount being dictated by source, overall meal composition and individual digestion capabilities. Some have suggested that 1 gram of fibre gives a net calorie contribution of ~1.5 calories, due to being converted to fatty acids in the intestines. However, the discussion is a very convoluted one. 

The exact type of fibre does matter, as does your unique gut bacteria. However, there is more to the discussion than this, as fibre does actually interact with the rest of the food you eat, serving to reduce the digestion of it. So it does potentially reduce the energy content of the diet overall, as it binds to and reduces the digestion of protein and fats. So it is hard to truly track the energy contribution of fibre. 

As a result, it is probably easiest to just treat fibre as a carbohydrate and count it as 4 cals per gram. You will likely be overestimating its energy contribution, but it does make tracking intake a whole lot easier. You can, of course, use a different number, but that number will just be a guess, and you will also have to remember that most tracking apps just track fibre as 4 cals per gram, so if you personally use a different number, you will have to keep track of that yourself. 

Slow Gastric Emptying and Increase Satiety

The next role of fibre is somewhat subjective (as not everyone experiences it to the same extent), but also has a physiological basis. Fibre slows gastric emptying, and as a result, it generally increases satiety. This is also compounded by the fact that most higher fibre foods are also very high volume and low calorie. 

So you will generally feel fuller by virtue of the fact that high-fibre foods are high volume and high fibre. However, even if you negate the fact that fibre is generally associated with high-volume foods, fibre itself does increase satiety. 

It is important to keep in mind that increased fibre intake is generally associated with increased satiety (and delayed gastric emptying), as this will influence your practices for a variety of goals. For example, if you are trying to eat a calorie deficit, this information is very important. You can use it to try and stave off excess hunger while eating fewer calories. 

However, it is also very important to know if you are trying to eat a calorie surplus. If you are trying to eat a calorie surplus and you are excessively full all the time, it is unlikely that you will be able to actually consume all the calories you need. 

So keep in mind that fibre increases satiety.

Glycemic Control

Fibre is one of the main reasons some carbohydrates are considered better for blood sugar regulation. As fibre effectively slows digestion down, it also slows the release of carbohydrates into the bloodstream, which in turn alters insulin release. 

This serves to leave you with a more even energy level and is very important to understand for those who have to manage their blood sugars more closely. With a fibre-containing meal, you don’t get the rapid digestion of carbohydrates and thus the large spike in blood sugars, which is then often followed by an energy crash as blood sugars drop more rapidly. This drop in blood sugar tends to result in hunger, which then impacts on dietary adherence. 

So not only does fibre make your diet more satiating, but it also potentially increases the likelihood that you will actually stick to your diet and not snack in between meals due to swings in blood sugar. So fibre is definitely something you should be aware of when designing a diet.

Detoxification

Now, beyond just contributing to your calorie intake and increasing satiety, fibre also plays a role in detoxification. This is generally what most people associate fibre intake with, keeping your toilet habits regular. You may not have thought of this process as a detoxification process before, but that is exactly what it is. However, purely helping with stool formation and regularity isn’t the full story of how fibre helps with detoxification.

Insoluble fibres will add bulk to stools, and they pull in water as they pass through the digestive tract, and this results in decreased colonic transit time. This is often something that confuses people, as fibre is touted to both delay gastric emptying, and then also increase intestinal transit time. 

But you must remember that the digestive tract isn’t just one organ and the effects fibre has on one section may not be the same in another section. Fibre delays gastric emptying (think stomach to intestines) while increasing intestinal motility (think intestines to anus). However, there are also differences in the type of fibre you eat, and thus different effects will occur. 

On top of that, you must layer on the population and current status of the individuals. If you have poor intestinal motility, and you only go to the toilet twice per week, fibre is likely to increase stool frequency (increase gastric motility). However, if you need to go an excessive number of times per day, fibre is likely to decrease stool frequency. 

It is effectively bringing things back into balance, so that you end up going to the bathroom with a normal 1-3 times per day frequency. 

So, the insoluble fibre contribution to detoxification is pretty easy to understand, it basically allows you to more efficiently go to the bathroom, and deposit waste products. Once you remember that the digestive tract is one of the areas where your body releases waste products (such as metabolic byproducts, “used” hormones etc.), you start to realise that having a very efficient and on-time waste disposal system is very important. You certainly don’t want waste just sitting in your bowels and potentially getting reabsorbed into the body.

Beyond this, we must also consider soluble fibre and its role in binding to bile acids. By binding to bile acids, and thus facilitating their excretion, soluble fibre serves to decrease the recycling of bile acids which can, in turn, decrease serum cholesterol levels. 

This, naturally enough, has implications for blood cholesterol levels, and is why those who are concerned with heart disease are encouraged to eat a higher fibre diet (along with reducing saturated fat intake, and of course, engaging in weight management and exercise as appropriate). 

We must also think a little bit deeper than this, and remember that hormones are made from cholesterol, so a high-fibre diet has the potential to interact with hormone synthesis. However, this is not really a concern for most people, but it does bear mentioning that high fibre intake has the potential to reduce hormone levels in the body. 

This is both good and bad. It is good for certain populations (such as those with PCOS or people at risk for reproductive hormone-related cancers) and it is actually quite often reducing the less effective (and often harmful) metabolites of hormones (by stopping them from getting reabsorbed in the intestines). However, it is a potential negative if you are eating a very high-fibre diet, as it may reduce hormone levels more than you want. 

But on the flip side, a low-fibre diet may increase hormones, as it isn’t decreasing the cholesterol pool. However, low fibre intake is associated with increased insulin resistance, which you certainly don’t want from a health perspective. Insulin resistance is also associated with lowered steroid hormone synthesis. 

However, this relationship is complex, and some insulin resistance may actually increase steroidogenesis as it leads to higher insulin levels. So there is a Goldilocks zone with this, and as a result, there is likely a sweet spot with fibre consumption.

Further to this, fibre is also involved in detoxifying carcinogens. This is both the potentially carcinogenic substances the body is trying to excrete (such as certain metabolites) and potential carcinogens that are ingested. 

Fibre binds to these carcinogens and reduces the potential that they come in contact with the gut wall. This is important for those who have a familial history of bowel cancers, and also for those who like to eat their food (especially meat) with a bit of charring or a bit on the burnt side (i.e. you may like your meat to have a crispy outer layer or your toast a little more blackened). 

As your body gets rid of things it can’t use or doesn’t want through the digestive tract, and fibre plays a role in this process, fibre thus plays a role in detoxifying the body effectively.

Feeding the Gut Microbiome

This is something that we have already stated, as we said that the gut bacteria are what break down some fibres in the large intestines. In popular media, this is often stated as fibre feeds the gut microbiome/gut bacteria. All it means is that they are digesting the foods you can’t digest, and they are feeding on what you can’t feed on. 

This is generally a beneficial arrangement, as in the process of breaking down these fibres, the gut bacteria also produce beneficial byproducts, such as the short-chain fatty acids mentioned earlier, acetate, propionate and butyrate. 

While a lot of the beneficial effects associated with fibre are related to the detoxification stuff, we simply can’t overlook the effects these short-chain fatty acids have on health. Butyrate, in particular, has many beneficial effects on the gut lining. 

However, beyond just the byproducts that feeding the bacterial populations generates, the actual populations of bacteria themselves have potential health-promoting effects. They serve to modulate the immune system and keep it vigilant for potential pathogens. They also interact with the inflammation systems of the body. The microbiome does also seem to influence your body composition (i.e. you can have an obesity-promoting microbiome)(however, there is more to this story than first meets the eye). 

While we won’t be digging much deeper into the microbiome, it does bear knowing right now that feeding a healthy microbiome does lead to positive health outcomes. While encouraging the growth of “bad” populations with poor fibre intake, is associated with ill health (the population of bacteria is somewhat dictated by the types of food you eat, especially being influenced by low fibre intakes). 

It does also bear mentioning at this stage, that some people will have populations of bacteria that simply don’t do well with certain fibres and this can result in negative effects when these populations interact with dietary fibres (this can range from mildly annoying effects such as some bloating and gas, all the way to very series inflammatory bowel issues). 

Absorption of Protein/Fats/Vitamins/Minerals

While most of fibre’s effects are quite positive, there are some negatives. I touched on this earlier but the consumption of fibre does actually reduce the absorption of many dietary components, both macronutrients and micronutrients. Fibre binds to some vitamins and minerals in the stomach and they are carried through without a chance to be absorbed. 

If you are getting your fibre from real food sources and not from a “manmade” fibre source, I would generally say the vitamin/mineral absorption isn’t a huge problem as you will generally be eating a higher proportion of vitamins/minerals with “real food”. However, this does bring up the point that if you are taking something like a multivitamin, I probably wouldn’t take it with a high-fibre meal. 

This is also somewhat of an issue for plant-based diets, as you get reduced protein absorption and you also potentially don’t get a full spectrum of amino acids. However, while it is somewhat of a concern, unless you are eating a ridiculously high amount of fibre every day, I wouldn’t be overly concerned about this. While I certainly wouldn’t be timing my high-fibre meals along with my multivitamin, outside of that, it isn’t a huge issue.

Health Benefits Of Fibre

While I have been discussing the roles of fibre, I know this can be a bit abstract, so I just want to touch on some of the actual health benefits of fibre. I know I generally tend to think in terms of the end effect, rather than the mechanisms that led to it, so I do just want to actually cover this.

Fibre intake is associated with many positive health benefits. Some of the association between fibre intake and better health outcomes is likely due to higher fibre foods generally being quite nutrient dense foods (and foods that have a lot of other bioactive compounds that may contribute to health). 

However, high fibre diets do seem to be associated with better digestive health, weight management, heart health, blood sugar control, colon health, and heart health, and is associated with reduced cancer risk.

A lot of attention is placed on the health benefits of fibre in relation to digestive health, and that is certainly a very important aspect, but fibre intake is associated with many more positive health effects too. 

Heart Health

Fibre intake is associated with better heart health and reduced cardiovascular disease risk. Soluble fibre binds to bile and helps remove it from the body, which serves to reduce cholesterol in the body. 

A high fibre diet is also linked to lower blood pressure. This benefit arises not only from the direct effects of fibre but also because many high fibre foods, such as fruits, vegetables, and legumes, are nutrient-dense and rich in potassium. Potassium is a key nutrient that helps balance sodium levels in the body and relaxes blood vessel walls, both of which play crucial roles in lowering blood pressure.

Additionally, high fibre diets are generally associated with better weight management. Fibre increases feelings of fullness and can reduce overall calorie intake, helping maintain a healthy weight. Since excess weight is a significant risk factor for cardiovascular disease, weight management further strengthens the heart health benefits of fibre.

When combined, these factors (improved cholesterol levels, lower blood pressure, and better weight management) all contribute meaningfully to overall heart health and a lower risk of cardiovascular disease.

Metabolic Health and Blood Sugar Regulation

Fibre plays a crucial role in promoting better metabolic health, with particularly strong benefits for blood sugar regulation. This is largely thanks to soluble fibre, which forms a gel-like substance in the digestive tract when it absorbs water. This gel slows down the absorption of sugar into the bloodstream, creating a steadier release of glucose and reducing the likelihood of sudden blood sugar spikes.

For individuals with diabetes, this effect is particularly valuable. By moderating the rate at which sugar enters the bloodstream, soluble fibre helps improve glycemic control, making it easier to manage blood sugar levels. This reduces the risk of hyperglycemia (high blood sugar episodes) and may also minimise the need for large fluctuations in insulin dosing for those managing diabetes with medication.

However, the benefits of fibre extend beyond immediate blood sugar control. Consistently stable blood sugar levels, supported by a high-fibre diet, help prevent the body from overproducing insulin. When the pancreas is frequently forced to release large amounts of insulin in response to rapid blood sugar spikes, it can lead to insulin resistance over time (a key driver of type 2 diabetes). By dampening these sugar spikes and reducing the demand on the pancreas, fibre helps maintain insulin sensitivity, lowering the risk of developing metabolic conditions like type 2 diabetes.

Ultimately, high fibre diets are pretty fantastic at helping to maintain and improve overall metabolic health and blood sugar regulation. As a result, they play a key role in reducing the risk of metabolic disease(s).

Reduced Risk of Cancer

The connection between fibre intake and colorectal cancer prevention is very robust. Fibre adds bulk to stool and speeds its passage through the digestive system, minimising the contact time between potential carcinogens and the lining of the colon and rectum. This reduces the likelihood of cancerous changes.

Additionally, soluble fibre feeds beneficial gut bacteria, which ferment the fibre into short-chain fatty acids (SCFAs) like butyrate. Butyrate has anti-inflammatory and anti-cancer properties, helping to maintain the health of colon cells and inhibit the growth of abnormal cells. By promoting regular bowel movements, reducing inflammation, and supporting a healthy gut microbiome, fibre creates an environment less conducive to colorectal cancer.

Beyond colorectal cancer, fibre consumption has been linked to reduced risks of esophageal, gastric, and lung cancers. By increasing stool bulk and diluting carcinogens in the digestive tract, fibre helps reduce exposure to harmful substances that could lead to cancers of the esophagus and stomach. 

Additionally, fibre’s anti-inflammatory properties and its role in supporting overall metabolic health may contribute to a lower risk of lung cancer, even in non-smokers.

Chronic inflammation is a common pathway for cancer development across various sites in the body. A high fibre diet helps counter this by fostering a healthy gut microbiome, which produces anti-inflammatory compounds like SCFAs. These compounds can lower markers of inflammation, such as C-reactive protein (CRP), and reduce the risk of inflammation-driven cancers.

Fibre rich foods such as fruits, vegetables, whole grains, and legumes are not only high in fibre but also packed with antioxidants and phytochemicals. These compounds combat oxidative stress and neutralise free radicals, which can damage DNA and trigger cancer development. The combination of fibre and these bioactive compounds provides a dual protective effect against a wide range of cancers.

Fibre’s benefits also extend to cancers influenced by hormones, such as breast, ovarian, and endometrial cancers. Fibre can bind to excess hormones like estrogen in the digestive tract and help remove them from the body. This process reduces circulating estrogen levels, which is critical since elevated estrogen is a significant risk factor for hormone-sensitive cancers, particularly breast cancer.

Improved insulin sensitivity from a high fibre diet further contributes to hormonal balance. High levels of insulin and insulin-like growth factors are associated with increased cell proliferation and tumour growth, so stabilising these levels through fibre intake may reduce the risk of hormone-related cancers.

Obesity is a well-documented risk factor for numerous cancers, including breast, endometrial, pancreatic, kidney, and esophagal cancers. Fibre plays a key role in weight management by increasing satiety, reducing overall calorie intake, and stabilising blood sugar levels. By helping maintain a healthy weight, a high fibre diet indirectly lowers the risk of obesity-related cancers.

Overall, fibre intake is very beneficial in decreasing the likelihood of many cancers developing.  

Longevity

Now, whenever we talk about the health effects of any component of the diet or indeed of training, we should always ask if any of this actually results in meaningful improvements in longevity. The fact that fibre is associated with many health benefits is meaningless if it doesn’t actually result in any benefit to either our lifespan or our healthspan. 

But, luckily for us, a high fibre diet is strongly associated with increased longevity. Research consistently shows that individuals who consume diets rich in fibre tend to live longer and have a lower risk of dying from chronic diseases. 

One of the most significant ways fibre impacts longevity is by reducing the risk of chronic conditions, which are leading causes of premature death worldwide:

• Heart Disease: High fibre diets lower cholesterol levels, improve blood pressure, and reduce inflammation, all of which contribute to a decreased risk of heart disease, a leading cause of death globally.
• Type 2 Diabetes: Fibre helps stabilise blood sugar levels, improving insulin sensitivity and lowering the risk of developing type 2 diabetes.
• Certain Cancers: Fibre’s role in reducing the risk of colorectal cancer and potentially other cancers, such as breast and ovarian cancer, can significantly contribute to a longer life.
• Obesity: Fibre promotes satiety and weight management, lowering the risk of obesity (a major risk factor for many chronic diseases) and metabolic syndrome.

Having a reduced risk for many of the big killers of humans is a pretty big win for fibre. While we classify fibre as something that isn’t an essential part of the diet, it is actually something that dramatically improves your health and longevity. The foods you have to eat to get sufficient fibre (fruits and vegetables) are also very robustly associated with better health. So ensuring adequate fibre intake is a really good proxy way to ensure a high-quality diet. 

Do You Actually Need To Eat Fibre?

Now, as I said, fibre is not classified as an essential nutrient, but it is still considered vital for good health. Essential nutrients are substances the body cannot produce on its own and must obtain from the diet to survive, such as vitamins, minerals, amino acids (from proteins), and fatty acids (from fats). 

While fibre is not technically essential for survival, it is highly beneficial for maintaining optimal health and preventing various chronic diseases.

Unlike essential nutrients, fibre does not directly participate in metabolic processes like energy production or the construction of cells. The human body can function in the short term without dietary fibre. However, this does not mean it is unnecessary, and its absence in the diet can lead to serious long-term health issues.

Fibre provides numerous health benefits, even though it is not directly involved in basic metabolic functions:

• Digestive Health: It supports regular bowel movements and prevents constipation.
• Cardiovascular Health: Soluble fibre lowers cholesterol and supports heart health.
• Metabolic Health: It helps regulate blood sugar levels and reduces the risk of type 2 diabetes.
• Gut Microbiome Support: Fibre acts as a prebiotic, feeding beneficial gut bacteria, which play a role in immune function and inflammation reduction.
• Cancer Risk Reduction: Fibre is linked to a reduced risk of colorectal and possibly other cancers.

But do you actually need to eat fibre? 

Well, the answer is technically no, you don’t need to consume fibre. However, by not including it you are likely going to have: 

• Digestive issues, such as constipation or diverticulosis.
• Increased risk of cardiovascular disease, type 2 diabetes, and certain cancers.
• Poor gut microbiome health, which may contribute to inflammation and weakened immunity.

Now, its absence from the diet won’t likely result in an immediate negative effect, but why anyone would want to increase their risk of poorer health intentionally is perplexing. You can make fruits, vegetables, tubers, wholegrains and legumes taste pretty phenomenal, and once you learn how to eat sufficient fibre, it isn’t that hard to do consistently. So there really aren’t a lot of good reasons why you would intentionally choose not to get the benefits of fibre.

Some people do have digestive issues, and can’t eat certain types of fibre. So for them, it may make sense to eat less or to be very specific in their fibre intake, but for everyone else, it is generally a much smarter choice to include sufficient fibre in the diet.

So how much fibre should you eat?

How Much Fibre Should You Eat?

To answer this question, and to allow you to more precisely tailor your own diet, it helps to understand what the general guidelines are for fibre intake from around the world. 

United States (Dietary Guidelines for Americans):

• Men (ages 19-50): Aim for 38 grams of fibre per day.
• Men (51 and older): 30 grams per day.
• Women (ages 19-50): 25 grams per day.
• Women (51 and older): 21 grams per day.
• These recommendations are based on consuming 14 grams of fibre for every 1,000 calories in the diet.

United Kingdom (Public Health England):

• Recommends a daily intake of 30 grams of fibre for adults.
• Encourages consumption of a variety of fibre-rich foods to meet this target.

European Union (European Food Safety Authority (EFSA)):

• Advises at least 25 grams of fibre per day for adults.
• Suggests higher intakes may provide additional health benefits.

World Health Organization (WHO):

• Recommends a minimum daily intake of 25 grams of fibre.
• The World Health Organization (WHO) emphasises high fibre diets as critical for reducing the global burden of chronic diseases.

Australia and New Zealand (National Health and Medical Research Council):

• Men: 30 grams of fibre per day.
• Women: 25 grams per day.
• Emphasises the importance of whole grains, fruits, vegetables, and legumes.

Canada (Health Canada):

• Men (ages 19-50): 38 grams per day.
• Men (51 and older): 30 grams per day.
• Women (ages 19-50): 25 grams per day.
• Women (51 and older): 21 grams per day.

As you can see, these guidelines all fall somewhere in the range of 20-38g of fibre per day, depending on age, sex and calorie intake. It should be noted that these recommendations are based largely on the recommended calories intake for these populations, and as such, if you eat more than the recommended calorie intake (which most people do), then you should actually be consuming more.

The average fibre intake in the Western world is significantly lower than the recommended levels. Most people in countries like the United States, the United Kingdom, Canada, and Australia consume only 15-20 grams of fibre per day, falling well short of the general guidelines.

How Much Fibre We Recommend

These major health organisations are putting out information for the masses, and thus have to really simplify things. However, we are generally coaching individuals to better optimise their diet or we are teaching coaches how to actually coach nutrition. As such, rather than fixed targets (like the above recommendations), we generally prefer to have targets that are actually tailored to the individual. 

So, we generally recommend that people get roughly 10-15 grams of fibre for every 1,000 calories they consume. We generally further caveat this by setting an “ideal” minimum target of 25g of fibre per day.

This allows you to have a bit more flexibility with the fibre target, while still allowing you to reap all of the benefits of sufficient dietary fibre. 

If you eat very few calories, you still ensure you get the health benefits (and extra satiety) of sufficient fibre. And if you eat a lot of calories, you also ensure that your fibre intake scales up proportionally. 

Using the previous example we have been using throughout this article series of the person eating 2000 calories per day, we would set their fibre target somewhere in the range of 20-30g per day. We would generally like to see them at least aim for 25g per day, this would be the ideal scenario. But as long as they are getting at least 10g of fibre per 1,000 calories consumed, they are likely in an OK place. 

Now, if they were in a deficit and were quite hungry, we might even go higher than this (as fibre will keep you fuller for longer), and conversely, if they had higher calorie requirements, we would initially hang out at the lower intake (10g per 1000 calories) and assess levels of fullness. If they were struggling to eat enough because they were too full, we would dial back intake.

Quick Summary: Set your fibre target somewhere in the range of 10-15g per 1000 calories, ideally aiming to consume at least 25g of fibre per day.

Tracking Fibre Intake

Tracking fibre intake, and by extension fruit/vegetable intake is a bit of a bone of contention in the fitness industry. Some people say you shouldn’t track vegetables and fibre as they are so low calorie and fibre isn’t really metabolised by the human digestive tract. However, others say you should track every single iota of calorie-containing particle that passes your lips. 

We are pretty laid back on this and the polarised right or wrong view on this, in our opinion, doesn’t really help anyone. We generally suggest people get roughly 10-15 grams of fibre for every 1,000 calories they consume. Most people who have never really tracked their fibre (or food in general), will usually struggle to hit their fibre targets, as most people really do under-consume fruits and vegetables in their diets. 

As a result, most people are going to have to track their fruit/vegetable and fibre intake for a while, and build an understanding of how much fruit/vegetables they have to actually eat to achieve their fibre goals. 

After you know what is required, then you can stop tracking your fruit/vegetable intake if you want, but you will still need to keep eating the same volume of fruits/vegetables each day. 

Those of you who like more accuracy in your diet, can of course keep tracking fruit/vegetable intake. Most people will eventually move to a more intuitive style of dieting (like we teach our clients and we teach on our nutrition course), and thus stop actively tracking fruits/vegetables. 

But again, you do actually need to keep eating them to achieve your daily fibre requirements. I am labouring this point because so many people don’t eat enough fruits/vegetables, and if they aren’t actively tracking their intake, they generally revert to low intakes.

Can You Eat Too Much Fibre?

While most people should be eating more fibre, there are some populations that may actually need to eat less fibre. And in some cases, you can actually eat too much fibre.

The most obvious population that may need to eat less fibre is people with specific medical conditions. Those with conditions like Crohn’s disease, ulcerative colitis, or irritable bowel syndrome (IBS) may need to temporarily reduce fibre during flare-ups or choose low-fibre options to minimise irritation.

Similarly, before and after certain surgeries, particularly involving the gastrointestinal tract, low fibre diets are often recommended to reduce stress on the digestive system.

Fibre is very satiating, and as such, many specific populations may need to limit their fibre intake so they can actually consume sufficient calories for their needs. Some of these populations include:

Young Children:

• While fibre is important for children, excessive amounts can fill them up too quickly, potentially preventing them from consuming enough calories or nutrients to support growth and development. 

Elderly Individuals with Low Appetite:

• Seniors who struggle with low calorie intake or malnutrition should be cautious about consuming very high fibre foods that may leave them too full to eat sufficient calories and nutrients.

Athletes and Individuals with High Energy Needs:

• Athletes requiring large amounts of calories may find excessive fibre intake challenging because it can cause fullness and make it difficult to meet their energy needs.

Even if you don’t fall into one of these categories, you can still eat too much fibre. So, what are some of the signs you may be eating too much fibre?

• Bloating and Gas:
  • Fibre ferments in the gut, producing gas as a byproduct. Excessive fibre intake can lead to bloating and flatulence, especially if your gut isn’t used to processing high amounts of fibre. This can sometimes be avoided by gradually increasing your fibre intake, or avoiding certain fibres, but it can be a sign that you are just eating too much fibre.
• Excessive Fullness:
  • Fibre rich foods are highly filling, and consuming too much may leave you feeling uncomfortably full, potentially suppressing your overall calorie intake.
• Constipation or Diarrhea:
  • Paradoxically, too much fibre (especially without adequate hydration) can lead to constipation. On the other hand, certain soluble fibres may cause loose stools if consumed in excess.

If you are experiencing any of these regularly, you may be consuming too much fibre. However, given that the vast majority of people under consume fibre, it is very rare that you will encounter someone who is eating too much fibre. 

Gradual Adjustments to Fibre Intake

Now, before I finish this section, I do just want to touch on the fact that you should ideally make gradual adjustments to your fibre intake, rather than big changes. While reading this, you may have realised that you are eating too little fibre and now want to drastically boost your intake. Well, before you do that, I have some tips for you to hopefully help you avoid experiencing discomfort.

1. Introduce Fibre Slowly:
   • Add fibre rich foods one at a time and in small amounts. For example, start by swapping refined grains with whole grains or adding an extra serving of vegetables to your meals. Don’t go from eating 5g of fibre per day to 50g. Slowly titrate your intake up over time.
2. Hydrate Adequately:
   • Drink plenty of water to help fibre move smoothly through your digestive system. This reduces the risk of constipation and discomfort.
3. Mix Fibre Types:
   • Balance soluble fibre (found in oats, fruits, and legumes) with insoluble fibre (found in whole grains, nuts, and vegetables) to support overall digestion. Don’t overemphasise one or the other.
4. Choose Tolerable Sources:
   • You may tolerate certain types of fibre better than others. Experiment with different foods to find what works best for your body.
5. Listen to Your Body:
   • If you experience persistent bloating, gas, or discomfort, you might be consuming too much fibre. Dial back slightly and adjust based on your tolerance.

Fibre Distribution

We are nearly through this article now, and I just want to tie up some loose ends. One of these loose ends is whether there is a better or worse way to distribute your fibre intake across the day. 

Well, the answer is that there is no best timing strategy with fibre and spreading fibre (and thus vegetable) intake throughout the whole day will likely give the best results. This will help stabilise blood sugar to some extent, but also ensure you are getting a variety of nutrients throughout the day. 

The only time I am not a huge fan of lots of fibre is just before training as most people find they can feel a bit bloated and somewhat sluggish if they overconsume fibre here. 

You could also argue that you don’t want to prioritise fibre after training, so you can restock your carb stores a little bit quicker, but this really isn’t a huge issue. 

The thing most people will usually struggle with here is getting some fibre at breakfast, and maybe even the lunch meal too. Similar to protein, most people really only get their fibre in during that evening meal, so you will likely have to actually focus a bit more on getting more fruits/veg/legumes at the other meals of the day. I will cover some high fibre options in a moment to help you solve this.

Fibre Quality

Now we turn our attention to fibre quality. A lot of this is just a discussion of carbohydrate quality and nutrient density. However, some people do have issues with certain fibres, so it can be helpful to just briefly expand on this. 

At this point, I just want to remind you to think of fibre as undigestible carbohydrates, and while it is visually appealing, try not to think of fibre solely as fibrous parts of plants. Thinking of fibre as undigestible carbohydrates really does allow you to understand this stuff much better than automatically connecting fibre and plants. 

While it is very easy to just say “vegetables” as a catch-all for fibre (and I do it all the time too), it isn’t completely accurate and to really understand this stuff, you do have to at least have a basic understanding that there is more to this than just “vegetables = fibre”.

There are many different identified fibres, such as arabinoxylans, cellulose, resistant starch, resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and indigestible oligosaccharides. There is no really good way to conceptualise and categorise these in a way that will allow you to make very easy snap decisions about whether that type of fibre is “good” or “bad” for individual needs. 

This is because you don’t actually digest these parts of the diet, so we aren’t talking about human physiology here (which we could then more easily generalise). No, we are talking about the interface between the gut microbiome and human physiology. This interface isn’t as well understood as we would like, and it is extremely variable between individuals and populations. So I simply can’t give you a very easy-to-understand generalised ruleset. However, I think we can certainly give you the cognitive framework to correctly think about fibre and thus make better choices on an individual basis.

I am going to categorise fibre into four distinct groups. This is for ease of discussion, and there is actually overlap. It should also be viewed as a generalised discussion and not specific to any fibres themselves (they would have to be evaluated on an individual basis). 

We are going to categorise fibre into soluble fibre, insoluble fibre, resistant starch and sugar alcohols. 

That gives us a good starting point for this discussion, as it covers the main types of fibre people are likely to encounter. But do realise it doesn’t cover everything. However, while it doesn’t cover everything, it does cover the most common sources of fibre you will encounter in the diet, and as such, understanding these should give you a starting point to start tweaking your diet towards a better fibre intake for you.

• Soluble fibre is up first, and as discussed in previously, soluble fibre is the fibre that can be dissolved in water, is easily fermented in the large intestines and quite often results in physiologically active byproducts (e.g. butyrate).
• Insoluble fibre is the fibre that can not be dissolved in water. It provides bulk to stools by resisting digestion and pulling in water as it passes through the digestive tract. It can be somewhat fermented in the large intestines. This “somewhat” fermentable aspect shouldn’t be overlooked.
• Resistant starches are starches (generally what people think of as carb sources are starch sources) that aren’t digested in the small intestines, and as a result, pass through to the large intestines (their structure makes them harder to digest than regular starch). They are insoluble, but also fermentable. As with the other categorisations, there are many types of resistant starch, and they all have different properties. However, this is just a generalised discussion. As these starches are insoluble and potentially fermentable, they can often have properties of insoluble fibre and soluble fibre. Resistant starches are naturally occurring in foods, but are also potentially added to processed food to increase the fibre content and/or change the texture of the food. Foods can also have different resistant starch amounts depending on how ripe they are (this is especially the case with bananas, as green bananas have a very high resistant starch content) and how they have been prepared (if you cook and then cool potatoes, for example, their resistant starch content goes up dramatically). This has many implications when we assess fibre quality.
• Sugar alcohols (or the broader category of polyols) can also potentially be considered as fibre. Polyols are a weird one as they effectively straddle the border between carbohydrates and alcohol. They are somewhat resistant to digestion by both humans and some bacterial populations. Their resistance to digestion is a lot of the reason for their inclusion in foods, as they aren’t metabolised by the mouth bacteria and as a result, don’t result in acid production which can contribute to tooth decay (as would happen when these bacteria digest other carbohydrates). However, polyols are fermentable and thus can “feed” certain populations of bacteria, and naturally, the more polyols you consume, the greater the prevalence of these bacteria (which may be good or bad for you as an individual). It bears mentioning that polyols probably shouldn’t be considered true fibre, as it can partially be digested and absorbed in the small intestines.

Now, the reason we have categorised these is purely for ease of discussion. As you will see in a moment, choosing a higher-quality fibre source is quite convoluted, and I don’t want to make it harder to understand by throwing in random specific fibres. So some sort of categorisation is needed to discuss things.

Fibre Quality Digestive Upset

The first consideration when assessing fibre quality is the issue of digestive upset. We want to choose fibre that doesn’t lead us to have digestive issues. These can range from fairly innocuous bloating all the way to actual digestive issues like IBS (irritable bowel syndrome). 

Choosing your fibre sources based on what your body responds well to is the first thing that goes into choosing a higher-quality fibre source. It is wholly irrelevant if a fibre type or specific source is said to have X, Y and Z benefits, if it causes you to feel like crap, get bloated and gassy, or be crippled in pain with abdomen cramping, well, it simply isn’t a high-quality source for you. 

This should be fairly obvious, but I know it is very hard to put this into practice when people are disseminating information without context to the individual. So you may repeatedly hear that you should be eating fibre, or that you should be eating certain fruit/vegetables/carbohydrates and they simply don’t sit well with you. 

So the first thing when deciding on fibre quality is “how does this make my tummy feel?” It isn’t exactly the most generalisable thing, but you don’t want generalities, you want specifics for the individual. 

You will have to experiment a little bit, and there is no real way around this. However, it is more complicated than just a simple case of doing this once and being done with it for life. No, unfortunately, the gut microbiome is a living super-organism, and your choices influence it. So what once caused you upset, may not in the future. What once was perfectly ok for you, may not be in the future. 

So you should not view this all as a fixed one-time thing. This is an area that you are going to have to investigate and play around with, and while it may seem complex, it effectively boils down to trying a few different sources of fibre and seeing which ones cause issues and which ones don’t. Then we can just base the diet around the fibre sources that don’t seem to cause issues.

Soluble fibre may be more of an issue as the gut microbiome interacts with it more than insoluble fibre. As such this is generally the first place I look when someone complains of digestive issues from eating fibre. The gut microbiome is responsible for digesting these fibres, and they do this through fermentation. This can result in issues for some people, as the process of fermentation by some bacterial populations can result in byproducts that leave the host (you, the human) feeling awful. 

This can be as simple as excessive gas production (such as hydrogen or methane), but could also potentially be other byproducts that we currently don’t have the full picture of with regard to their impact and interaction with the host. 

This is the area that most people should look at when assessing fibre quality as it relates to digestive issues. As the gut microbiome interacts most with these fibres, and it is likely that a lot of digestive issues (but certainly not all) can be related back to the gut microbiome, this is naturally the starting point for assessing fibre quality. 

The assessment is quite easy in theory, you simply assess whether that soluble fibre sits well with you or not. If not, then reduce your exposure to it. However, in practice, this is extremely hard to do and will likely involve using a restrictive, elimination-style diet to really get to the bottom of the issue.

Insoluble fibres are next in our assessment of fibre quality as it relates to digestive issues. There are multiple reasons why insoluble fibres may cause digestive upset. The first is simply the same reason that soluble fibre can cause issues, and that is that it can be fermented in the large intestines. This is often overlooked as insoluble fibres aren’t generally considered to be fermented, however, there potentially is some fermentation occurring. 

Secondly, as insoluble fibres pull water in as they pass through this can be both beneficial for digestive issues, but also potentially negative, as it can do some weird things with water balance within the digestive system, but also potentially cause some uncomfortable distention. 

As with soluble fibre, you will have to assess how you respond on a case-by-case basis to insoluble fibre. With fibre, you need to assess both the fibre quality, but also how fibre quantity fits into this equation. This is especially true of insoluble fibres, as you may be perfectly fine with them until you get to a certain quantity, and then it causes issues.

Resistant starch is next up in our consideration of fibre quality. Resistant starch (depending on the exact type) has properties that straddle soluble and insoluble, and combined with the fact that most people are simply unaware of its existence, resistant starch often gets misunderstood. 

We must consider resistant starch when trying to assess fibre quality, especially as it relates to digestive issues. Remember, foods can have different resistant starch amounts depending on how ripe they are and how they have been prepared. This can help to explain a lot of things that really confuse people when they try to really take control of their diet and try and address their GI upset. 

You will often encounter people saying something like, “I eat this food one day and have no issues, and then I eat it another day and have issues”, or something to that effect. Quite often when you do a bit of digging you will find they are eating variable amounts of resistant starch, completely unintentionally. 

They will one day eat a very yellow banana and have no issues, but then the next day they eat a more green banana and suddenly have issues with bananas. Or they will prepare a batch of potatoes as meal prep for the week, and the first day have no issues, but then the next day when they eat the exact same meal, suddenly they have issues. 

So this is something that must be considered, but it is also something that is extremely hard to truly dial in on as it is quite hard to really quantify the amount of resistant starch in a food in any objective manner for a normal person, without access to a lab. 

You can do a search of resistant starch foods, and try to minimise intake, but this effectively makes you potentially minimise a lot of your carbohydrate sources. You can also be left having to make some rather annoying lifestyle changes, such as not batch-cooking meals for the week ahead (which is a practice that allows a lot of people with real lives to actually stick to their diet).

Eating small amounts of certain fibre may also cause issues that are hard to correlate with a particular food. This is rather infuriating, as it can be extremely hard to really dial in on the actual issue. This is particularly the case with sugar alcohols. 

Something as seemingly innocuous as chewing on chewing gum that contains sugar alcohols can result in gut upset later on in the day. You may not even correlate the two things, as you didn’t even swallow the chewing gum. You may not even realise that it could be connected and as a result can feel like you haven’t eaten anything out of the ordinary that could be causing your issues. 

I have seen quite a few individuals cut out chewing gum and solve their gut issues. Does that mean chewing gum is bad? No, not at all. It just means, for these individuals, at that particular time, chewing gum didn’t sit well with them. The diet is an ever-evolving thing, and you must constantly be tweaking it based on the body’s needs and responses. This is especially true of fibre, as you aren’t the only one making the decisions, your gut bacteria also have a say.

Sugar alcohols are actually one of the really hard ones to get a grasp of because different sugar alcohols have different effects. While they do resist digestion, they are actually absorbed in the small intestines and do interact with the actual human entity. 

However, they are often considered to be slowly absorbed, and as a result, can cause issues. This is due to the fact that firstly, some of them can be fermented (and thus bacteria may start feeding on them while they hang around in the gut), but more often the issue with them is related to their ability to pull water into the intestines. 

This ability to change the osmotic conditions of the gut can result in quite a bit of distention (as the gut fills with water). This may result in discomfort, however, it also may not result in discomfort. The distention will likely be visible though, and this may explain quite a lot of the posts you see on social media about bloating from people into fitness, as this population is also more likely to consume polyols (as they are often marketed as a low-calorie option). 

To truly understand all of this, you still must assess things on an individual basis, assessing both how different sugar alcohols affect you (and your gut bacteria) and how the amount of sugar alcohol you ingest affects things (you may be fine with a small amount, but large quantities cause digestive upset).

Overall, while it is very easy to just blame fibre and only consider it when discussing digestive issues (it certainly is a good starting point), to really dig into digestive issues, doing some form of an elimination diet may be the process that is needed for a lot of people. This will allow them to really get a better handle on fibre quality, along with other potential contributing factors. 

One such diet that is very successful for this is the low FODMAP diet. However, as it does somewhat pertain to fibre quality, we will quickly touch on it here. A low FODMAP diet is a style of dieting that tries to limit the amount of fermentable oligosaccharides, disaccharides, monosaccharides and polyols. For certain populations, a low FODMAP diet is an absolute godsend for helping them to deal with their digestive issues. 

Effectively, it is an elimination-style diet, with the elimination being the Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. This can work well for those who have issues with high FODMAP foods, although it certainly is not a cure-all. However, for someone with digestive issues, a low FODMAP diet is as good a starting point as any other and it does seem to result in very positive outcomes for many individuals. 

However, as I have tried to impress on you, fibre should be thought of as indigestible carbohydrates (not necessarily of plant origin), thinking in a FODMAP framework is just a further refinement of that, focusing only on the fermentable fibres. This is certainly a smart refinement when discussing populations that seem to have gut bacteria-related issues, as the bacteria are the ones doing the fermenting, it does potentially miss some fibres that you personally are having issues with. 

This is potentially due to some fibres that aren’t traditionally considered fermentable (such as insoluble fibres), are actually fermentable by some populations of bacteria. So a low FODMAP diet isn’t a cure-all, and while it is a good starting point, I personally prefer to just use the framework of isolating particular fibres/foods that an individual has issues with. This is a laborious process, and as a general shotgun starting point, a low FODMAP diet (or other elimination style diet) works well.

I am well aware that this section hasn’t told you exactly how to improve fibre quality, but this is such an individualised thing that there simply is no way I can give you generalised advice here. You will have to assess the foods eaten on a food-by-food basis and using the above information, decide whether that is a “good” or “bad” fibre source for you at this point in time (this may also change over time, so figuring this out once, unfortunately, doesn’t set things up for life).

Fibre Quality and the Microbiome

Now, we have touched on this repeatedly in the above section, but mainly from the perspective that the gut microbiome influences how you react to the type of fibre you eat. However, this relationship goes both ways, and the type of fibre you eat does influence the gut microbiome itself. 

The microbiome is effectively a living super-organism, and you do have some control over the population of bacteria present, by virtue of how you choose to eat. So it is modifiable. The gut microbiome does have direct interactions with your overall health status. While it is beyond the scope of this article, we will touch on some key points here, as it influences how we think about fibre quality. 

You will see a lot of hype and hyperbole as it relates to the gut microbiome, especially as it relates to obesity. This is due to a lot of work done in rodents, which isn’t necessarily applicable to humans (rodents practice coprophagy (eating faeces) and humans don’t, and as a result likely have different responses than seen in rodent experiments). 

However, even beyond the extremely limited application of these experiments to humans, it belittles the fact that the microbiome is very influenced by the type of diet you eat. It is also dynamic across time, and fluctuates even across the day. Your morning microbiome could actually be vastly different than you afternoon or evening microbiome.

So keep it in mind when you read any research on the microbiome affecting the individual, as it is modifiable. Just because someone has a potentially obesity-promoting bacterial population doesn’t mean this is something they are stuck with for life, as the food they choose to eat does affect the bacterial population present to a large degree (it may, however, take time to shift to a less potentially obesogenic population).

As you can influence the microbiome with the food you eat, and fibre is the thing that interacts with the microbiome the most, this naturally leads us to rank fibres higher if they result in a better, more health-promoting microbiome. However, it does bear mentioning that this whole discussion is extremely convoluted and not fully elucidated in the research. 

This is firstly because we don’t have a full picture of the actual bacterial populations of the gut, but mainly because we simply don’t know how these populations interact with each other. We do know that some populations function to feed other populations of bacteria (this is often called cross-feeding). This occurs by some bacteria breaking down the fibre you eat, and then the breakdown products serving as a fuel source for other bacteria (which they may break down into other byproducts which may serve as a fuel source for other bacteria again, and so on). So we don’t have a full picture here, and as a result, you should be very sceptical when reading information on the gut microbiome in general.

With that said, we do have some information that allows us to start the process of choosing fibres based on what we want to prioritise. This paper does go into more depth as to how the different fibre types that you eat affect specific bacterial populations. Now, you could try to use that information and bias your diet towards one type or another, however, we simply don’t have enough information to make a very good recommendation as to how your microbiome should actually look. 

While this information is very interesting to know, and there will likely be some extremely enlightening data emerging over the next few years, ultimately, it doesn’t actually hugely impact our practices. While you can try to influence your bacterial populations, effectively, your practice just ends up looking like what I suggested above. You will end up just eating different fibres, assessing whether it results in positive or negative outcomes for you and then continue to refine things for the rest of your life.

While we have focused on fibre and the microbiome here, I do want to make it clear that the other components of the diet (such as protein, fats, polyphenols etc.) do affect your microbiome, as do your overall lifestyle habits (such as exercise habits, sleep habits, stress status etc.). So while fibre is a big player, it is not the only thing that affects the microbiome. A lot of the research on the microbiome is in its infancy, so you certainly don’t need to be an expert in the microbiome to make good dietary decisions.

Fibre Micronutrients and other Dietary Components

Beyond solely looking at fibre, we must remember that generally macronutrients come packaged in a food matrix. So we must consider the food matrix itself, and the other nutrients contained within it. This is especially true when discussing fibre and when discussing the microbiome. 

As eating fibre does potentially reduce the quantity of both macro and micronutrients we can digest and assimilate, looking at the entire food matrix makes a lot of sense. So we want to ensure that we are maximising the amount of nutrients we are eating, assuming that the total amount we actually digest and assimilate is going to be reduced. 

Effectively, you want to also maximise the nutrients that come with your fibre. So focusing on eating whole food sources is probably your best bet. Most “real whole food” sources of carbohydrates will contain some form of fibre, and also contain a whole host of micronutrients. 

This section shouldn’t need a lot of discussion as I think most people would agree that maximising your nutrient intake is just plain and simple good practice. So this means that when looking at fibre quality, we would naturally prioritise fibre sources that are more nutrient-dense. This is fairly easy to do as most natural fibre sources do naturally contain a very high density of micronutrients, phytonutrients and polyphenols, so you don’t necessarily need to think about this too much. 

However, as we live in a world where the market provides for every need (once you have the necessary money), keeping this prioritisation on nutrient density in mind is very good practice. Achieving your fibre targets by virtue of supplementing with a fibre powder or by eating polyol-rich protein bars likely isn’t going to give you all the benefits you could be getting from a diet that is centred around real whole food sources of fibre.

Fibre Quality Summary

So that is what goes into assessing fibre quality. I realise that this isn’t either the most enthralling content or the most actionable content. Essentially I am just telling you to eat fibre, and then assess how you respond to it. Not exactly the most high-resolution insight into fibre quality, but it is actually the best way to go about this whole process. 

While you can read and try to interpret all the research, ultimately it is irrelevant until you actually start experimenting with your own response. There is no generalisable one-size-fits-all approach to fibre quality, it is extremely individual to you and your unique microbiome. 

But hopefully, this section on fibre quality has started the gears turning in your head, and gives you a launching point for further experimentation and research. From a little bit more practical perspective, you could think of this stuff from an actual food perspective as that quite often makes it easier to begin the experimentation process and then start tweaking things.

So you could focus on foods, and while they generally have a mix of fibres, it can be a little bit easier to actually tweak things with a broader, but more intuitive categorisation. So you could break things down as:

• Fruit
• Vegetables
• Beans/Legumes
• Whole Grains
• Starches (somewhat of a proxy for resistant starch, although resistant starch may be present in the other categories)
• Sugar Alcohols

This isn’t high-resolution thinking on fibre quality, but it does make it a little bit more practical to start the process of assessing whether a fibre is better or worse for you as an individual.

Ultimately, the discussion of fibre quality comes back to a process of trial and error and then ranking fibre as higher quality if it sits well with you and doesn’t cause digestive issues. But it does bear keeping in mind that this isn’t a fixed thing and your response to certain fibres can change throughout your life.

High Fibre Foods

Now, with all of that in mind, I just want to finish this article by briefly going through some good sources of fibre (although this does need to be individualised) and to give you some meal ideas for how you could incorporate more fibre in your diet. 

From working with a lot of people, I know this is where a lot of people struggle. It is all well and good to know the theory behind why fibre is important, but knowing how to actually increase teh fibre content of your diet is another story all together. 

So, I really just want you to focus on getting some ideas about which foods could help you increase fibre in your diet, and how you can eat fibre at more of your meals.

• Note: The calorie and fibre content can vary based on preparation methods and specific product brands. It’s advisable to check nutrition labels for precise information.

As you can hopefully see, in a lot of cases, your best bet for fibre, especially from a calorie perspective, is to get it from fruits and vegetables. But to make this more concrete, here are some ideas for how you can include more fibre in your diet. 

High Fibre Meal Ideas

Breakfast

1. Chia Protein Pudding with Greek Yogurt and Berries
   • Chia seeds soaked in almond milk, layered with Greek yoghurt, and topped with fresh raspberries and blueberries.
2. Oats with Whey Protein and Nut Butter
   • Rolled oats cooked with almond milk, mixed with whey protein powder, a tablespoon of almond butter, and a topping of flaxseeds.
3. Egg and Avocado Toast
   • Whole grain toast topped with mashed avocado, poached eggs, and a sprinkle of hemp seeds.
4. Protein Smoothie Bowl
   • Blend spinach, frozen berries, a scoop of protein powder, and almond milk, topped with granola and chia seeds.
5. Cottage Cheese with High-Fibre Granola
   • A bowl of low-fat cottage cheese, topped with high-fibre granola, diced pear, and a drizzle of honey.

Lunch

1. Grilled Chicken and Lentil Salad
   • Grilled chicken breast served over a salad of lentils, spinach, cherry tomatoes, cucumbers, and a lemon-tahini dressing.
2. Quinoa and Tuna Bowl
   • Quinoa mixed with canned tuna, diced vegetables, and a vinaigrette made with olive oil and lemon juice.
3. Black Bean and Turkey Chili
   • A hearty chili made with ground turkey, black beans, diced tomatoes, onions, and spices.
4. Chickpea and Grilled Salmon Salad
   • Grilled salmon served over a bed of arugula, chickpeas, cucumbers, and a citrus dressing.
5. Tofu Stir-Fry with Edamame and Brown Rice
   • Stir-fried tofu and vegetables, with shelled edamame and a side of brown rice for extra fibre and protein.

Snacks

1. Hard-Boiled Eggs with Veggie Sticks and Hummus
   • Hard-boiled eggs paired with carrot and celery sticks dipped in hummus.
2. Greek Yoghurt with Chia Seeds and Nuts
   • Plain Greek yoghurt mixed with chia seeds, a handful of almonds, and a drizzle of honey.
3. Cottage Cheese and Mixed Berries
   • Low-fat cottage cheese topped with raspberries, blueberries, and a sprinkle of flaxseeds.
4. Roasted Chickpeas and Protein Shake
   • A portion of roasted chickpeas with a shake made from almond milk and protein powder.
5. Turkey Roll-Ups with Whole Grain Crackers
   • Slices of turkey wrapped around avocado and cucumber, served with fibre-rich whole grain crackers.

Dinner

1. Grilled Chicken with Quinoa and Roasted Vegetables
   • Grilled chicken breast served with a side of quinoa and a medley of roasted broccoli, carrots, and sweet potatoes.
2. Salmon and Lentil Stew
   • Poached salmon in a lentil stew made with onions, tomatoes, and spices.
3. Chicken and Black Bean Bowl
   • Crispy chicken and black beans over a bed of brown rice, topped with avocado and salsa.
4. Turkey and Sweet Potato Casserole
   • A baked casserole with ground turkey, sweet potato cubes, spinach, and a sprinkle of low-fat cheese.
5. Shrimp and Chickpea Curry with Spinach
   • Shrimp cooked in a coconut milk-based curry with chickpeas, spinach, and spices, served with a side of quinoa.

Now, a lot of these meal ideas are just to get you thinking about how to incorporate more fibre in your diet. You don’t have to follow them to the letter. In reality, what most people end up doing to increase their fibre intake is they add some more fruit to their breakfast, snack on some fruit, add some more salad to their lunch and maybe some beans, and then add more vegetables to their dinner. 

Once you start focusing on your fibre intake, you will find the right balance of things and settle into a good rhythm. But to make things even easier, here are some quick tips to help you include more fibre in your diet:

Switch to Whole Grain or the “Brown” Version of Your Carbohydrates

• Choose whole wheat bread, brown rice, and whole grain pasta over white versions.
• Opt for oats or whole-grain cereals for breakfast.

Add Beans, Lentils, or Chickpeas to Meals

• Toss black beans or chickpeas into salads, soups, or pasta dishes.
• Use lentils as a base for stews, curries, or bolognese.

Incorporate Nuts and Seeds

• Sprinkle chia seeds, flaxseeds, or sunflower seeds into yoghurt, oats, or smoothies.
• Snack on a handful of almonds or walnuts for a fibre boost.

Eat More Vegetables

• Fill half your plate with vegetables at lunch and dinner.
• Use frozen veggies for convenience (they’re just as nutritious, if not more so, than fresh ones).

Add Fibre to Your Breakfast

• Top cereal or yogurt with high-fibre granola or fruit like raspberries or sliced banana.
• Add a tablespoon of psyllium husk or flaxseed to smoothies or oatmeal.

Choose High-Fibre Snacks

• Keep air-popped popcorn or whole-grain crackers on hand for a quick bite.
• Choose fruits with skins you can eat, like apples, pears, and berries, for an easy snack.

How Much Fibre Should You Eat Conclusion

Hopefully that all has helped you better answer the question of how much fibre you should eat. Depending on your background, you may have realised you are eating more or less than you need. But the good thing is, you can always make dietary changes. It is rare that someone will be completely stuck in a position where they can’t move their diet to be more in line with the recommendations. It can certainly be difficult to change, but it is possible.

Dietary change does just take some time and effort. If you need help with this, you can always reach out to us and get online coaching, or alternatively, you can interact with our free content.

If you want more free information on nutrition, you can follow us on Instagram, YouTube or listen to the podcast, where we discuss all the little intricacies of exercise and nutrition. You can always stay up to date with our latest content by subscribing to our newsletter.

Finally, if you want to learn how to coach nutrition, then consider our Nutrition Coach Certification course, and if you want to learn to get better at exercise program design, then consider our course on exercise program design. We do have other courses available too. If you don’t understand something, or you just need clarification, you can always reach out to us on Instagram or via email.

Paddy Farrell

www.triagemethod.com

Hey, I'm Paddy!

I am a coach who loves to help people master their health and fitness. I am a personal trainer, strength and conditioning coach, and I have a degree in Biochemistry and Biomolecular Science. I have been coaching people for over 10 years now.

When I grew up, you couldn't find great health and fitness information, and you still can't really. So my content aims to solve that!

I enjoy training in the gym, doing martial arts and hiking in the mountains (around Europe, mainly). I am also an avid reader of history, politics and science. When I am not in the mountains, exercising or reading, you will likely find me in a museum.