We live in an age of immediacy. People are more inclined to take things at face value if it sounds like what they want. What we lose in this pursuit is how the idea or concept came about and how it really works. The ‘What’ can help you in the short term, but the ‘how’ is necessary for you to keep the result you gained.

To achieve effective and healthy weight loss many adhere to the rule of 80% (the influence of diet) and 20% (the influence of exercise). Let’s equip you with the reasoning behind these stats to better understand how this works.

As a general rule, in order to lose weight, you are told to eat at a caloric deficit. So, eating less than what your body expends. To understand this concept of how much we should be consuming we will revisit our mathematics.

The 80% diet and 20% exercise rule finds its recorded foundations with scientist, Max Wishnofsky (1958) who suggested that 1 pound (0.45kg) of fat is approximately measured as 3,500 calories. Using this principle, many fitness professionals and gurus follow the following formula: If your goal is to lose 0.45kg of fat per week, you will need to reduce your daily calories by 500 from your standard diet, therefore, 500 calories x 7 days = 3,500 calories reduced = 1 pound per week of fat loss (Wishnofsky M, 1958).

In light of this, let’s put 500 calories into perspective. It takes less human effort to reduce 500 calories from a diet than it is to perform 60 minutes of Zumba at your highest intensity (no breaks or slacking off), every single day. Due to various limitations such as time, money and physiological repercussions of over training, not everyone has the capacity to engage in such high intensity exercise every day of the week. This is essentially where the concept was drawn from and why the diet has 80% of the focus, rather than exercise. 

In theory, it sounds great! But in practice, there’s a whole heap about exercise physiology that needs to be taken into account.

This rule was turned on it’s head by more recent studies on hormonal and metabolic adaptations from low calorie dieting. A 2014 study looked at disproving the 80/20 concept in relation to long term effective weight loss. Researchers found that over time the body’s regulatory mechanisms and metabolic processes worked less in resting state, while on a consistently low calorie diet with no changes in energy expenditure. They also found the low energy intake lead to an overall reduction in the thermic effects of eating and levels of resting state thermogenesis. Meaning, the participants were burning less calories at rest, compared to those that varied their training and nutrition (Thomas et al., 2014).

Any diet, will work in the short term because it challenges the body’s efficiency. If the body becomes too efficient at a certain process, it will use less energy and effort to maintain it, therefore, the dreaded plateau ensues.

However, the more you enquire into the training and nutrition protocols of advanced trainers, competitors and athletes, you will generally see changes when the diet AND training protocols are adhered to whether that is 80/20 or 50/50. It is tough to out-train a poor diet, but you can lose weight without exercise. It’s about understanding the importance of both that will allow you to build your body for longevity.



Thomas, D., Gonzalez, M., Pereira, A., Redman, L. and Heymsfield, S. (2014). Time to Correctly Predict the Amount of Weight Loss with Dieting. Journal of the Academy of Nutrition and Dietetics, 114(6), pp.857-861.

Wishnofsky M. Caloric equivalents of gained or lost weight. Am J Clin Nutr. 1958;6(5):542–546.


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