AUDIE CORNISH, HOST:
NBC's reality show "The Biggest Loser" turns dieting into a grueling training regime fit for gladiators. The victor of this past season was Roberto Hernandez.
(SOUNDBITE OF TV SHOW, "THE BIGGEST LOSER")
BOB HARPER: (As himself) Your current weight is 188 pounds. You lost 160 pounds. You're the biggest loser, Roberto.
CORNISH: But once the lights, cameras, nutritionists and trainers go away, the contestants found many regain much of the weight they lost in the show, sometimes 100 pounds or more because they're biology works against them. The research appears in today's issue of the journal "Obesity."
And for more on the significance of the findings, we turn to Dr. Donna Ryan. She's an obesity researcher and clinician at the Pennington Biomedical Research Center in Baton Rouge, La. Welcome to the program.
DONNA RYAN: Thank you.
CORNISH: Now, we should mention that you weren't involved in doing this research, which was on the front page of The New York Times today. But I can imagine in your community it's huge.
RYAN: Absolutely. I think the most important aspect of this research is it really reinforces how biologically determined body weight is, that it's not just a matter of willpower to produce weight loss and to keep weight off.
CORNISH: So let's give people some background. The study tracked contestants from 2009. That's season eight of "The Biggest Loser." And they found that most of the 16 contestants had put back pounds they lost. This has to do with their metabolism, right?
RYAN: Correct. We know that a reduction in metabolic rate is a normal biologic response to weight loss. This is a disproportionate reduction in metabolic rate. And in a way, it's a metabolic handicap, so that after weight loss two people who weigh exactly the same, the one who is reduced will require less calories, less energy to sustain that weight than a person who's never been reduced.
So those "Biggest Loser" participants who were reduced - actually to sustain their weight, had to eat 500 fewer calories a day than individuals of the very same weight who were never reduced.
CORNISH: So let's say you've lost a lot of weight. Let's say you lost 100 pounds. Now you're 150 pounds. Another person who's 150 pounds, they can still eat the calories they want, right? But you've got to eat less to maintain that level.
RYAN: That is correct. You must eat less than a person who weighs exactly the same as you.
CORNISH: But you'll be hungrier - right? - because the research is also talking about another way your body fights against it.
RYAN: Absolutely. So all of the hormones that your body produces that regulate appetite are also altered disproportionately. So you're hungrier than that person. You're more susceptible to highly rewarding foods to snacking.
CORNISH: You know, people are going to hear this and think that essentially the contestants on "The Biggest Loser" might be worse off now than they were before they lost all this weight.
RYAN: Absolutely not. I think the most important thing to know about "The Biggest Loser" is that in weight loss, it's not about how much weight you lose. It's about your health status. And we know that you don't need to lose dramatic amounts of weight to really get a lot of health benefit.
So those people of "The Biggest Loser" after six years, they were still reduced on average by about 10 percent. And that's associated with a lot of health benefits.
CORNISH: At the same time, I think it might be disappointing for these contestants and for other people - right? - who have had extreme weight loss. What advice do you have for them?
RYAN: You know, I think as a society, we need to be more accepting of variations in body size and less accepting about the health consequences of body weight. So if we can get improvements in health, that's really what weight loss is all about. So I think we need to shift our focus away from how we look and our body size to how a little bit of weight loss - 5 to 10 percent can really produce dramatic improvements in body health.
CORNISH: Dr. Donna Ryan, she's an obesity researcher and clinician at the Pennington Biomedical Research Center in Baton Rouge, La. She joined us via Skype. Thanks so much.
RYAN: Thank you, Audie.
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