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 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 (about 149 kg) and
ended at an average weight of 200 pounds (about 91 kg).
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,
dipped 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, as reported in the journal Obesity.
The slower the metabolism, the more a person has to cut back on
calories in order to keep from gaining weight.
“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 author
Kevin D. Hall of the National Institutes of Health (NIH) in
Bethesda, Maryland.
Their metabolisms didn’t speed up again when they regained the
weight, he told Reuters Health by phone.
Perhaps counterintuitively, participants whose metabolisms had
slowed the most at the six-year point tended to have regained less
weight.
Metabolism appears to act like a spring, Hall 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.
“Your body is working to defend your energy stores - really your fat
mass,” said Dr. Michael Rosenbaum of Columbia University Medical
Center in New York who was not part of the new study.
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“When that fat mass is diminished (either by eating less or
exercising more) most of us respond by changes in brain circuitry
that increase our tendency to eat and changes in neural and
endocrine systems, and especially muscle, that make us more
metabolically efficient - it costs fewer calories to do the same
amount of work,” Rosenbaum told Reuters Health by email.
The Biggest Loser is an extreme weight loss program, and these
results may not translate to other methods or approaches to weight
loss, Hall said.
“The aim of The Biggest Loser program is entertainment, not
sustained contestant weight loss,” said professor John R. Speakman
of the University of Aberdeen. “It is not a prescription for how to
change your life.”
The only weight loss method that seems to avoid metabolic pitfalls
is gastric bypass surgery, Hall said. People who undergo Roux-en-Y
gastric bypass surgery experience a similar dip in metabolic rate
along with massive weight loss at the six month point, but after one
year they have the expected metabolic rate for their size, rather
than the much reduced rate of Biggest Loser contestants, he said.
“It may be that there is something special about bariatric surgery,
resetting some set point in the body to not resist the weight loss,”
he said.
But The Biggest Loser results are not uniformly dire, Hall said. 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.
“You don’t need to lose that much weight to see benefits,” he said.
“A lot of people conflate the cosmetics of weight loss with the
health benefits of weight loss.”
SOURCE: http://bit.ly/26LZo3f Obesity, online May 2, 2016.
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