When you first start trying to lose weight, the math is straightforward: To lose 1 pound, create a 3,500-calorie deficit by eating less and moving more. But as the weight comes off, the body’s metabolism slows as it tries to maintain a “set point” weight, and the math stops working. People need a greater caloric deficit to keep losing weight. And for most people, the weight creeps back up over time.
What if there was a way to offset this metabolic adaptation? That’s the question researchers writing in the International Journal of Obesity attempted to answer by studying weight loss response to 2-week “diet breaks.”
Fifty-one men with obesity were randomized to 16 weeks of either continuous caloric restriction (the typical “diet”) or alternating blocks of 2 weeks of caloric restriction with 2 weeks of weight maintenance. For both groups, “caloric restriction” was 67% of weight maintenance requirements. Calorie intake was adjusted to account for reductions in resting energy expenditure caused by weight loss (the “metabolic adaptation” described above).
At the study’s end, the researchers found that greater weight and fat loss and a smaller decrease in resting energy expenditure occurred with the intermittent energy restriction, or “dieting breaks,” than with continuous caloric restriction. Note that unlike in intermittent fasting studies, in which participants eat as much as they want on non-fasting days, the caloric intake during the maintenance phase was not ad libitum but rather based on the number of calories needed for weight maintenance. The study was highly controlled; participants received most of their meals and snacks, and dietary adherence was closely monitored. More work needs to be done to see if similar outcomes play out in free-living settings.