Belt-size boomerang
Study reveals how hard body fights weight loss,
Danny Cahill stood, slightly dazed, in a blizzard of confetti as the audience screamed and his family ran on stage. He had won Season 8 of NBC’s reality television show The Biggest Loser, shedding more weight than anyone ever had on the program — an astonishing 239 pounds in seven months.
When he got on the scale for all to see that evening, Dec. 8, 2009, he was lean, athletic and as handsome as a model. He weighed just 191 pounds, down from 430.
“I’ve got my life back,” he declared. “I mean, I feel like a million bucks.”
Cahill left the show’s stage in Hollywood and flew directly to New York to start a triumphal tour of the talk shows, chatting with Jay Leno, Regis Philbin and Joy Behar. As he heard from fans all over the world, his elation knew no bounds.
But in the years since, more than 100 pounds have crept back onto his 5-foot-11 frame despite his best efforts. In fact, most of that season’s 16 contestants have regained much if not all the weight they lost so arduously. Some are even heavier now.
Yet their experiences, while a bitter personal disappointment, have been a gift to science. A study of Season 8’s contestants has yielded surprising new discoveries about the physiology of obesity that help explain why so many people struggle unsuccessfully to keep off the weight they lose.
Kevin Hall, a scientist at a federal research centre who admits to a weakness for reality TV, had the idea to follow the Biggest Loser contestants for six years after that victorious night. The project was the first to measure what happened to people over as long as six years after they had lost large amounts of weight with intensive dieting and exercise.
The results, the researchers said, were stunning. They showed just how hard the body fights back against weight loss.
“It is frightening and amazing,” said Hall, an expert on metabolism at the National Institute of Diabetes and Digestive and Kidney Diseases. “I am just blown away.”
It has to do with resting metabolism, which determines how many calories a person burns when at rest. When the show began, the contestants, though hugely overweight, were burning a normal number of calories for people of their weight. When it ended, their metabolisms had slowed radically and their bodies were not burning enough calories to maintain their thinner sizes.
Researchers knew that just about anyone who deliberately loses weight will have a slower metabolism when the diet ends. So they were not surprised to see that The Biggest Loser contestants had slow metabolisms when the show ended.
What shocked the researchers was what happened next: As the years went by and the numbers on the scale climbed, the contestants’ metabolisms did not recover. They became slower, and the pounds kept piling on. It was as if their bodies were intensifying their effort to pull them back to their original weight.
Cahill was one of the worst off. As he regained more than 100 pounds, his metabolism slowed so much that, just to maintain his 295 pounds, he now has to eat 800 calories a day less than a typical man his size. Anything more turns to fat.
The struggles the contestants went through help explain why it has been so hard to make headway against obesity, which afflicts about a quarter of Canadian adults.
Their experience shows that the body will fight back for years. And that, said Dr. Michael Schwartz, an obesity and diabetes researcher at the University of Washington, is “new and important.”
“The key point is that you can be on TV, you can lose enormous amounts of weight, you can go on for six years, but you can’t get away from a basic biological reality,” said Schwartz, who was not involved in the study. “As long as you are below your initial weight, your body is going to try to get you back.”
The study’s findings, published Monday in the journal Obesity, are part of a scientific push to answer some of the most fundamental questions about obesity.
The hope is that this work will lead to new therapies that treat obesity as a chronic disease and can help keep weight under control for life.