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'The Biggest Loser' contestants gain again: Why weight keeps coming back

Losing weight is hard. Keeping off pounds is even harder. That's a fact of life for the vast majority of people struggling with weight.
/ Source: TODAY

Losing weight is hard. Keeping off pounds is even harder. That’s a fact of life for the vast majority of people struggling with weight control. But the question is: how do you fight your own body?

Image: The Biggest Loser
Ali Vincent was the first female to win on the show with an 112-pound weight loss. Vincent recently posted to Facebook about gaining the weight back. NBC

That’s the focus of a very small study recently published in the journal Obesity. Investigators at the National Institutes of Health tracked 14 contestants from “The Biggest Loser” —13 of whom regained much or all of their weight in the 6 years following their initial weight loss during the competition —to learn more about factors that might impact weight regain.

RELATED: 'Biggest Loser' winner Ali Vincent reveals weight gain, says 'I feel like a failure'

Previous research has shown that people who lose weight show a drop in their resting metabolic rate (RMR) — which is the number of calories needed daily to meet the body’s needs. RMR is basically the same as what we call “metabolism.” At a higher weight, there is more body mass to maintain, and so more calories are needed. With weight loss, metabolism slows in response to body size. This is basic biology.

Biggest Loser contestant Danny Cahill
Season 8 winner Danny Cahill (from 430 pounds to 191) was one of the participants of the NIH study, according to the New York Times. He now weighs 295 pounds.NBC

In the new study, when the participants — including season 8 winner Danny Cahill, who was featured in a report in the New York Times — regained weight, their RMR stayed low, and did not adapt back to the higher rate, when their weight was higher. The result: it became harder to lose weight again. These data show that the expected metabolic shift downward occurred with weight loss, but did not shift back up with weight regain, meaning future weight loss will be even harder.

If you're trying to lose weight and keep it off, this sounds discouraging. But it’s important to point out that this very small group — only 14 people — and their unique and severe weight-loss regimen doesn’t necessarily apply to most people managing their weight. These participants were diagnosed with severe (morbid) obesity and their rate of weight loss was extremely rapid — much faster than that observed for many bariatric surgery patients.

RELATED: One basic diet change may be all you need to be healthier

It's not a surprise that some of the "Biggest Loser" contestants gained weight back —the struggles of many of the show contestants have been closely followed for years. And it's not biologically surprising to find more extreme metabolic changes resulting from such a major stress to the body.

One participant dropped 239 pounds in 7 months. It is not yet known whether such rapid weight loss has a different impact on metabolism than if that weight were lost over several years. Simply put, these 14 people chose a path very different and unique from almost everyone else working on weight loss.

That’s why long-term research is so important.

It's never over

It’s not only metabolic rate that predicts weight loss and re-gain. Many studies show that other biological, behavioral, and environmental factors play a significant role. Every person is unique, and the contribution of each of these factors will vary, creating a very different pattern of weight loss and re-gain.

A key factor: when the participants were done with the show, they returned to their daily lives, without the support of nutritionists, psychologists, trainers, exercise specialists, and physicians — all who play a significant role. And these environmental and behavioral factors are shown to be essential to long-term weight-loss success.

feet on scale
Anyone who has lost a significant amount of weight knows that lifestyle change is hard, and it's never over. Shutterstock

RELATED: 3 tips for long-term weight-loss success

What remains a reality for anyone who has lost weight and kept it off, as well as the millions who simply are trying to stay at a stable weight, is that lifestyle change is hard, and it’s never over.

Daily focus on lifestyle, perseverance (and support) can help offset biological issues, but the challenge is to look at the whole picture, and not one factor.

While biology might not always work in your favor, you can succeed if you set a realistic goal for a target weight. Maybe the “biggest” loser is not always better long-term maintenance. Losing an amount of weight for health improvement can be far less than that for the “perfect” body.

RELATED: What the 'ideal body' looks like for men and women

Because there appears to be a body weight at which all people more naturally gravitate, if you’re already closer to that weight, it’s a lot easier to stay on track. Your body will fight to get there.

The good news: one of the best ways to offset the natural slowing of metabolic rate after weight loss is with physical activity.

RELATED: Tips from the world's fittest 96-year-old

Boosting both the amount and intensity of exercise can help, and is a key factor in avoiding weight re-gain.

Madelyn Fernstrom, Ph.D is NBC News Health and Nutrition Editor