80% Diet + 20% Exercise = 0% Evidence

“Weight loss is 80% diet and 20% exercise.”

“Abs are made in the kitchen.”

“You cannot out train a bad diet.”

These are three common statements regarding the disproportional impact of nutrition on body composition that are bandied around so frequently many people accept them as fact. While they make great sound bites and appear logical under brief examination, what do any of them look like when applied to your lifestyle?

What changes do you make to your routine to ensure that it adheres to the 80% rule?

What is the recipe to make abs?

What makes a diet good or bad in the first place? [This might help].

I am certainly being a touch disingenuous by taking each of these statements so literally. All they are trying to do is highlight the importance of nutrition to getting results and convey the fact that many people eat too much food for the amount of exercise they do. Both of which are important messages that often ring true.

We know that the energy balance hypothesis states that we need to create an energy deficit to lose body fat, whereby energy expenditure exceeds energy intake. Neither diet or exercise is more important in facilitating this deficit - they simply both play a role on either side of the scale. Increasing energy expenditure via exercise creates an energy deficit if energy intake remains the same, as does decreasing energy intake through food while maintaining the same expenditure.

To say that nutrition must be the initial focus of a body recomposition strategy is like telling someone the only way to save for a house deposit is to spend less. Yes, that is what they need to do if their income remains the same. But if they were to increase their income by working more hours or taking on a second job, they might be able to hit the savings goals even faster than reduced spending alone. If they were able to do both at the same time, it would be done even quicker!

Just because a strategy works well for the majority does not mean it is the rule for an entire population. Therefore it is important to present a range of body recomposition strategies to an individual, so we can work out what suits them instead of trying to push one approach to everyone.

The question we really want to answer is: will reducing energy intake, increasing energy expenditure, or a combination of both be the best way to create an energy deficit for the individual?


The Ratio

As always, the answer to that question is ‘it depends’... on the individual, their goals, experience and lifestyle. Whilst I am sure that does not answer the question to any degree of satisfaction for you, the reality is there is no magical split of training and nutrition that promises better results than any other variation. But that is not to say the idea of having a ratio such as 80% diet 20% training is completely useless.

Instead of thinking of the 80-20 ratio as being where weight loss results come from, we can think of it as the proportion of the target energy deficit from exercise and nutrition. We can use this ratio to quantify different strategies to what facilitates the best adherence. Let’s say someone was eating 2500 kcal/day and wanted to induce a 20% energy deficit of 500 kcal/day.

They might find that when they start exercising they feel great and gain confidence in themselves to take on the challenge of changing their food intake. They might be starting out at 90% training and 10% diet, which would be an extra 450kcal/day from exercise and -50kcal/day from food intake.

Or they instead might gain confidence from controlling their food intake without any exercise, then they can start to increase the training after seeing some progress. So here they try a 90% food and 10% food split, where they cut 450 kcal/day from their diet and only increase energy expenditure by -50 kcal/day.

Or maybe a mix suits them best - some small nutrition changes and additional exercise to get them moving in the right direction and then we can scale it up from there. They might be starting out at 50% - removing 250 kcal/day from the diet and burning an extra -250 kcal/day through activity.

A little bit of trial, and error, can give valuable insights into what an individual responds well to. Many people find the approach they thought they would not like actually works best. An example would be someone who hates exercise and thinks they will not adhere, which often means they are starting from a low fitness base. Once they add a couple of training sessions in per week, they make rapid progress and begin to enjoy the benefits of training, including the tangible benefits from their recent physical exertion.

Don’t Underestimate Exercise

Many people start out wanting a solution with minimal exercise. If you were to offer most people the same amount of weight loss for either eating 25% less food everyday or training hard for 45-minutes per day for the next three months, most people would take less food despite the physical and mental benefits that the exercise would bring.


In practical application, there is no need for directions of body recomposition strategies to be binary. Somewhere in between is the option to eat 15% less food and do 45-minutes of training three times per week. Such an approach might allow more food and a manageable exercise load, particularly for someone new, than the more extreme alternatives.

When we increase exercise, there are physiological adaptations independent of fat loss such as increased cardiovascular output and strength. The confidence derived from adherence is also quite different. While nutritional adherence feels good, sometimes you feel as if this is what you should have been doing all along and you are just meeting that requirement. Whereas with training, be it primarily strength or fitness orientated, you become able to do things that you physically were not capable of just a matter of weeks or months ago.

Of course, you know you should have been training for longer, but there is that satisfaction that comes from achieving something that was purely the result of hard work both now, and in the past to get there, that I think is more noticeable from training than nutrition. That is why I have noticed, from a purely anecdotal view, that people who gain strength and fitness also become more confident and tend to have more benefits associated with mental health and wellbeing.

Do Both

The long term progression of any body recomposition strategy includes both training and nutrition. There is only so long we can solely reduce energy intake, just as there are upper limits on the training capacity of general population clients. At this point, we need to slide the ratio back towards the middle and focus on making it as sustainable as possible.

But in the early stages, when the focus is primarily on finding the most adhereable way to facilitate an energy deficit, you should try different approaches and then continue on with whatever works best. And even if you think the higher-exercise approach is not right for you, try it for a couple of weeks, you might just be surprised!


Tom Fitzgerald