Study finds modest diet and exercise can sustain weight loss

You don’t have to be as extreme in your exercise as Biggest Loser contestants to be successful in weight loss, according to a study funded and conducted by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health.

NIDDK senior investigator Kevin Hall, PhD, analyzed the individual effects of daily strenuous exercise and a restricted diet by examining data from 11 participants from the reality television program The Biggest Loser. The program shows obese adults losing large amounts of weight over several months.

Researchers measured body fat, total energy expenditure and resting metabolic rate—the energy burned during inactivity—three times: at the start of the program, at week 6 and at week 30, which was at least 17 weeks after participants returned home. Participation in the program led to an average weight loss of 128 pounds, with about 82 percent of that coming from body fat, and the rest from lean tissue like muscle. Preserving lean tissue, even during rapid and substantial weight loss, helps maintain strength and mobility and reduces risk of injury, among other benefits.

Hall used a mathematical computer model of human metabolism to calculate the diet and exercise changes underlying the observed body weight loss. At the competition's end, diet alone was calculated to be responsible for more weight loss than exercise, with 65 percent of the weight loss consisting of body fat and 35 percent consisting of lean mass like muscle. In contrast, the model calculated that exercise alone resulted in participants losing only fat, and no muscle. The simulation of exercise alone also estimated a small increase in lean mass despite overall weight loss.

The simulations also suggest that the participants could sustain their weight loss and avoid weight regain by adopting more moderate lifestyle changes—like 20 minutes of daily vigorous exercise and a 20 percent calorie restriction—than those demonstrated on the television program.

"This study reinforces the need for a healthy diet and exercise in our daily lives," said NIDDK Director Dr. Griffin P. Rodgers. But it’s a relief to know we don’t have to work out for several hours every day to be successful! A combination of healthy eating and daily exercise can help all of us be “Biggest Losers.”