Six years after dramatic weight loss on the reality TV show “The Biggest Loser,” most contestants in a recent study had regained the pounds – and on top of that, their metabolism had slowed and they were burning fewer calories every day than they did before their appearance on the show.
Researchers studied 14 contestants who participated in the 30-week competition, which involves intensive diet and exercise training.
They started at an average weight of 328 pounds (149 kg) and ended at an average weight of 200 pounds (91 kg).
Weight and body fat increased, metabolism declined significantly
Six years later, when the six men and eight women went to the National Institutes of Health for follow-up measurements, their weight, on average, was back up to 290 pounds. Only one participant hadn’t regained any weight.
Similarly, percent body fat started at an average of 49 percent, declined to 28 percent and returned to 45 percent over time.
But resting metabolic rate did not follow the same pattern.
The group as a whole on average burned 2,607 calories per day at rest before the competition, which dropped to about 2,000 calories per day at the end.
Six years later, calorie burning had slowed further to 1,900 per day.
The slower the metabolism, the more a person has to eat fewer calories in order to prevent weigh gain.
“There used to be a mythology that if you just exercised enough you could keep your metabolism up, but that clearly wasn’t the case, these folks were exercising an enormous amount and their metabolism was slowing by several hundred calories per day,” said senior researcher from the National Institutes of Health (NIH) in Bethesda, Maryland.
The participants’ metabolisms didn’t speed up again when they regained the weight.
Perhaps counterintuitively, participants whose metabolisms had slowed the most at the six-year point tended to have regained less weight.
Extreme weight loss reduces metabolism, increases appetite
Metabolism appears to act like a spring, the researchers said: the more effort you exert to lose weight, the more it stretches out, and the harder it will spring back, regaining and holding onto the fat that was lost.
When that fat mass is reduced (either by eating less or exercising more) most people respond by changes in brain circuitry that increase the tendency to eat. As well, changes in nerve and hormone systems, especially in muscle, that make us more metabolically efficient. In other words, you burn fewer calories to do the same amount of work.
Keep in mind, The Biggest Loser is an extreme weight loss program, one that’s not sustainable in real life, and these results may not translate to more modest approaches to weight loss.
The Biggest Loser results are not completely dire, though. On average, the group regained much of their weight but did maintain about 12 percent weight loss even after six years, had better cholesterol profiles, and none had developed diabetes during follow-up.
Source: Obesity, online May 2, 2016.
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