A question that often gets asked in the health and fitness world is how lean can you get using a flexible dieting approach (if it fits your macros, IIFYM)?
A lot of people in the industry claim you physically can’t get stage lean (i.e. as lean as a body builder on stage) utilising a flexible dieting approach. People are told that if you actually want to get very lean, you have to eat only whole, minimally processed, nutrient-dense foods. Any deviation from specific foods (think chicken, broccoli, brown rice, cod etc.) or an exact meal plan, will ruin your efforts to actually get very lean.
These people often claim that the “chemicals” in certain foods will ruin your progress, or that certain foods have specific properties (such as the ability to thin the skin), or that the hormonal response to certain foods will ruin your fat loss goals.
While others on the opposite end of the spectrum, preach that flexible dieting is the only way to diet to get stage lean. They themselves go on fat loss diets, or know people that have competed and gotten themselves in extraordinary shape and ridiculously low body fat using a flexible dieting approach But these are outliers, right?
There are also others again on the side of a more flexible approach who get into very good shape, despite “terrible” food selection, or with very poor relationships with food or general food practices (i.e. fasting so they can eat large “cheat” meals that fit their macros).
So with all this anecdotal information out there supporting both sides of the argument who do you actually believe?
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How Lean Can You Get Using A Flexible Dieting Approach?
Well like with most things, we support a more moderate approach to the diet (and you can read more about how to set up a diet here).
The laws of thermodynamics are king when it comes to fat loss. Energy balance is the biggest driver of either weight loss or weight gain, however, it is ludicrous to suggest that hormones don’t play a part in this equation, or that food selection doesn’t either. It is also ludicrous to use the energy balance equation, to justify the fact that you have a terrible relationship with food and no dietary discipline.
To lose fat you must consume fewer calories than you expend in a day, that much is very abundantly clear. Anyone who argues with that is actually ignorant.
They are claiming that the laws of thermodynamics that govern the entire universe somehow don’t apply to the human body. Energy can neither be created nor destroyed and just because the person claiming that calories don’t matter doesn’t understand all the processes that potentially affect this equation, doesn’t give them permission to discredit the equation because of their ignorance.
However, just because thermodynamics is never wrong doesn’t mean calories are the only important aspect of a diet.
An inadequate protein diet that is matched in calories to an adequate protein diet, will result in a different body composition outcome at the end of a diet. With the low protein diet, the calorie deficit will indiscriminately result in weight loss, and both fat and muscle will be lost. While in the adequate protein diet muscle mass loss will be minimised and ideally wouldn’t occur at all.
So while calories are still king, the macronutrient content of a diet does also matter.
This is not to mention the individuality of this too. Some people handle carbohydrates better, while others perform better on a higher-fat diet. Some people feel satiated on higher-protein diets, while others feel full and bloated on high-protein diets. The individuality of the actual individual must be taken into account when dieting, and general recommendations would be just that, a general recommendation. You will need to customise this to your individual situation.
This individuality is also why some people “need” a meal plan, and others “need” more flexibility in their diet selection. The physiological aspect of a diet is only one aspect, the psychological one is also an important consideration. If you are better able to stick to a diet, it is obviously a better diet for you. This can be argued for either side.
The hormonal response to food is another consideration that can’t be ignored, even from an adherence aspect. If you are consistently eating crappy food (that fits your calories and macros) you will most likely find it harder to actually stick to your diet, especially if you are trying to feel satiated on a very high-sugar diet. The fact that micronutrient intake is compromised in diets that are typically higher in “junk” food is another consideration, although eating a diet that only allows 5 foods like a typical “bro diet” will also lead to poor micronutrient intake.
So who is actually right?
Can you get lean with a more “flexible” dieting approach?
Yes.
If calories and macronutrients are matched, there is no reason either of these dieters couldn’t get to the same low body fat levels.
Does that mean everyone should utilise a flexible dieting approach?
No.
Despite people becoming zealots on either side, neither approach is inherently better than the other. There are aspects from both sides that would obviously make dieting easier, and more sustainable long term both in terms of adherence and actual progress made.
Flexible or Restrictive?
You see the lower your calories get, such as in a competition dieting phase, the more “bro” your food selection probably should look. If you are dieting on lower carbohydrates, and you are blowing your entire daily carbohydrate target on a bowl of cereal, you are likely not going to get the results you want.
Not because a bowl of cereal will throw you off plan hormonally or metabolically in any serious way, but purely because you will be much more likely to binge and fall off your diet plan if you aren’t structuring your daily diet in a way that allows you to feel satiated.
I would also argue the lower your calories are, the lower your “flexible” calories should be. Everyone in the flexible dieting community likes to say they have an 80/20 or 90/10 approach to dieting meaning they allow only 20-10% of their diet to come from less than optimal food choices, however, these people are often the ones that have a “treat” every day of the week.
You could argue that having a daily “treat” may be psychologically better for them in terms of adherence to their diet, but I would rather see this person address why they need to eat some calories as a “treat” every day.
10% of your diet if you are eating 4 meals a day, is only 2.8 meals per week that should be allotted as “treat” food. 20% is 5.6 meals as ‘treats”. That sounds like a lot (or a little depending on what side of the argument you are on) but you must also consider your calories in this argument too.
If you are dieting on 2,000 calories, 10% is only 200 calories per day that should be allowed as “treat” foods or 400 calories at 20%.
I have repeatedly seen people “treat” themselves twice a week with 1,500+ calorie meals. Which is 3,000+ a week, and much more than the supposed 10-20% they claim to be allotting themselves.
However, having said that and to answer the original question, yes there is actually no physiological or psychological reason why you can’t diet using a flexible dieting approach and get as lean as someone eating a more “bro diet”. However, dieting like a kid in a candy shop is not conducive to your long-term goals, and while occasionally fitting in some foods you have been missing out on is a very good idea, it generally shouldn’t make up a huge component of your diet.
I would rather see someone deal with the underlying reasons they feel they NEED to consume these binge-esque quantities of food, or why they NEED to eat “treat” foods on a daily basis.
Eating a diet that is conducive to long-term success is the real goal of any diet. Sticking to a strict meal plan generally leads to huge blowouts once the “diet” ends and all the restricted foods are now freely available.
These restricted dieters are generally the ones that blow up after a diet, gaining 10-15+kg in a matter of a few weeks. The fact they have been restricted for so long means they have built up a huge amount of cravings and once they allow the floodgates to open, they can’t close them.
While the people utilising the more flexible dieting approach tend to be better able to deal with the post-diet period as they have been having small bits of the foods they crave throughout the whole diet and don’t feel nearly as restricted, they may not have things nailed down either.
Being too flexible with your diet and developing a poor relationship with food as a result (doing these binge-restrict calorie-controlled days, doing excessive amounts of cardio to allow more calories (binges) to be fit in, or not actually eating a micronutrient-dense diet and just eating crappy food sources “because they fit”) is something that unfortunately happens far too often.
The Middle Ground
A middle-ground balanced approach is likely best for actual long-term progress. Don’t be overly restrictive in your food choices, or over-flexible in your approach; eat a well-balanced diet with lots of lean meats, tons of veggies and a limited amount of “treat” foods (save these for special occasions or when you are craving them).
When eating a calorie and macronutrient-appropriate diet, whether the diet is made entirely of “whole” foods or “junk” foods will not lead to a quantifiable difference in body composition once the micronutrient needs of the body are also met.
However, from a long-term health (both physical and mental) perspective eating like an actual human, will lead to the best results.
IIFYM has been given a bad rap because people use it to justify their terrible eating habits, and to blatantly disregard the fact that food source does matter to an extent as a carb isn’t technically just a carb (the ability to stick to a high-sugar diet long term or the fact that high sugar intake does actually require a higher micronutrient intake), a fat isn’t just a fat (fats having different carbon length, meaning you technically get different amounts of ATP from them and different fatty acid types (saturated vs unsaturated) have different effects in the body) and a protein isn’t just a protein (proteins have different amino acid profiles and eating a low leucine diet definitely won’t get you that toned physique you desire).
Bro diets also get a bad rap because they tend to be overly restrictive and have some very arbitrary rules that don’t actually have a physiological basis.
But, whichever diet you actually utilise, it is still calories that determine how lean you will get. You could genuinely eat sugar, whey and olive oil and get to 3% body fat. Would that be a good idea? Hell no, but thermodynamics does still apply to humans whether you think it does or whether you think it doesn’t.
So, how lean can you get using a flexible dieting approach?
As lean as you want to. However, that doesn’t mean you should use a flexible dieting approach. You have to use the right tools for the job, and flexible dieting is only one tool in our tool box. It has many pros, and many cons, and the devil really is in the detail and the implementation.
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Paddy Farrell
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.