Can diet breaks improve fat loss?
Weight loss is determined by the balance between calories burned (energy expenditure) and calories consumed (energy intake). Dieting lowers calorie consumption (energy restriction), with the aim to create a negative energy balance to induce weight loss.
However, energy restriction also results in an (unwanted) decrease in energy expenditure. This metabolic adaptation is called ‘adaptive thermogenesis’ and can make it harder to keep losing weight. Can this adaptation be influenced by taking short dieting breaks?
This study investigated the effect of diet breaks on weight loss in obese men. Participants were divided into two groups: 1) normal dieting group: energy intake 33% below maintenance calories for 16 weeks or 2) diet breaks group: energy intake 33% below maintenance calories for 16 weeks, but with a 2-week diet break (eating at maintenance) after every 2 weeks of dieting. Therefore, both groups had the same total caloric deficit, but it took the diet breaks group 30 weeks instead of the 16 weeks in the normal dieting group.
Fat loss was greater in the diet breaks group compared to the normal dieting group (12.3 vs 8.0 kg). Lean body mass loss was not different (1.8 vs 1.2 kg).
There was no change in body weight during the diet break periods, indicating that the subjects adhered to the research protocols.
Both groups showed a reduction in resting energy expenditure, but the reduction was smaller in the diet break group. This suggests that diet breaks may reduce adaptive thermogenesis.
It should be noted that while some other studies have also observed improved body composition as a result of diet breaks, others have not. It’s not yet clear under which conditions diet breaks are effective.
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