Biggest Loser study shows why rebound weight gain almost unavoidable
12 May 2016
It's well known that metabolism slows when people diet, and this is often cited as contributing to rebound weight gain, when they stop dieting.
However, new research is indicating that people's metabolism stays suppressed, even after they regain the weight. It would be expected that as the participants gained weight, their resting metabolic rate - the measure of how many kilojoules their body burns up at rest - would rise too.
The study of contestants in The Biggest Loser series shows that despite re-gaining substantial weight in the 6 years after they left the series, their resting metabolic rate remained at the same low level that was measured at the end of the competition.
The US researchers note the contestants’ average resting metabolic rate was approximately 500 calories per day lower than would be expected based on their body composition and age. This is known as metabolic adaptation.
The findings suggest long-term weight loss requires a concerted effort to combat the effects of a slower metabolism.
In contrast, the researchers note that a group of people who had gastric bypass surgery for weightloss experienced significant metabolic adaptation 6 months after the surgery but had no detectable metabolic adaptation after one year despite continued weight loss.
“It is intriguing to speculate that the lack of long-term metabolic adaptation following bariatric surgery may reflect a permanent resetting of the body weight set-point,” say the authors.