First of all I think its important to highlight the distinction between refeeds and diet breaks.
Refeeds are scheduled very short term spikes in energy intake, usually around maintenance calories or slightly above. Typically between 1-3days. Usually exclusively from carbohydrates.
Diet Breaks share the same premises but are much less aggressive hovering around maintenance calories for anywhere between 1-2weeks, though could be extended longer.
What happens in to the body in an extended caloric deficit?
The body is smart.... (homeostasis).
It's always trying to remain the same. Meaning it's going to adapt to energy restriction in many ways in attempts to reduce energy expenditure. In the nutritional science world this is called adaptive thermogenesis..... The nemesis of any client or coach with a mission set out to lose weight.
Can this effect be manipulated by introducing scheduled caloric spikes in order to trick the body and decrease the reduction in total daily energy expenditure (TDEE).
The Matador Study;
one of the most popular studies done back in 2018. This approach compared two groups of obese men who were placed in the same 33% caloric deficit, however; The intermittent dietary restriction (INT) group took a 1wk scheduled diet break after every 2wks of deficit vs. the Control (CON) group which went the entire time in a restricted state over 16weeks.
When it came to weight loss the INT group experienced a 47% greater weight loss over the span of 16weeks. Even more astonishing is that at the 6month follow up the INT group had lost 80% more weight than the CON group.
The chart below breaks down all the effects of the study in detail; Pretty amazing right?!
Several studies have been done on refeeds and diet breaks since. Mostly on untrained populations with BMIs over 30 although a few more recent studies have been done on highly active individuals often with resistance trained backgrounds.
A recent 2021 study performed by Seedler and colleagues was done on 38 resistance trained females with a 25% reduction in caloric restriction for 6wks with a similar diet break strategy as the MATADOR study in CON vs. INT groups with much less remarkable effects but a noticeable difference in reduced eating disinhibition (the tendency to overeat in response to negative emotional states). though the full study is not available yet you can find the abstract online.
My two cents.
This non linear approach to dieting is a win win for me. Especially in situations with those who have a significant amount of weight to lose, are trying to achieve a very extreme level of lean (such as bodybuilding competitors or weight specific athletes), those with more adaptive metabolisms or simply individuals who struggle with dietary adherence long term.
From a psychological standpoint I find this strategy helpful for most. It appears that overall this method provides more self regulatory ability, positive affect, better coping strategies to overcome temptation, more motivation to pursue goals and better adherence overall.
The greatest potential downfall would be for those that struggle with adherence in less rigid restriction who may be at risk of a planned "diet break" becoming more "binge" like. but I'd question whether dieting may be the right plan of action for those individuals to begin with.
Of course by utilizing the diet break method you'd be extending the final goal destination.. but to me the pros vastly outweigh the cons in the long game of weight loss maintenance.
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