Building frequent “breaks” into your diet could help you lose more weight and keep it off for longer than attempting to cut calories, uninterrupted, for months on end, according to new weight-loss research from the University of Tasmania in Australia. If the findings can be replicated, the weight-loss method could be a promising and more sustainable technique for people who struggle to commit to a new way of eating.
“Cheat” days, or more relaxed dieting rules on weekends, are a common, if controversial, recommendation for people trying to lose weight. The argument is mainly psychological: Cheat days help people feel less restricted, and planned indulgences give them mental stamina to follow through with a healthy eating regimen on the days they need to follow their diet.
But lead researcher Nuala Byrne argues there may be a biological, as well as a psychological, reason resting periods help people lose more weight. Namely, they help fight against “adaptive thermogenesis” ― when the body responds to caloric restriction as if it were starving. During adaptive thermogenesis, metabolism slows in the body’s attempt to hold onto every calorie it receives. As illustrated dramatically in the “Biggest Loser” study from 2016, losing weight appears to make one’s resting caloric needs plunge even lower than would be expected for their new weight and body composition, sometimes for years after a person has lost the fat. The process makes it increasingly difficult to lose or maintain weight as time goes on, and frighteningly easy to gain it all back.
Byrne and her colleagues theorized that if dieters could take a few weeks to rebalance caloric needs after a little bit of weight loss, they could reduce the effect of adaptive thermogenesis on their bodies. They decided the periods of dieting and rebalancing would last for two weeks each, based on a classic semi-starvation study that found metabolism plunges for about two weeks after initial calorie restriction before adjusting to a new body weight and composition.
To test the theory, Byrne recruited 51 obese, sedentary men and divided them into two groups. Researchers provided food that ensured the control group ate only two-thirds of the calories needed to sustain their body weight, continuing to adjust food amounts as the men lost weight over the course of 16 weeks.
Researchers did the same for the intervention group, but in increments of two weeks. So, for the calorie-restriction weeks,…