“The Biggest Loser” Study Predicts Sustained Weight Loss Through Modest Changes in Diet and Exercise
With a validated computational model for predicting weight loss, a research study has quantified the dramatic diet and exercise intervention strategy employed in “The Biggest Loser” television program. It found that this intervention would not be sustainable over time, but a more modest and feasible diet and exercise could maintain the weight loss. “The Biggest Loser” program, although highly successful, has been criticized for portraying an extreme diet and exercise intervention regimen that could raise unrealistic expectations for weight loss. The program shows obese adults losing large amounts of weight over several months, initially isolated on a ranch, followed by an extended period at home. Scientists took advantage of this cost-efficient opportunity to study the television program’s 16 obese contestants already engaged in an intensive lifestyle intervention. As part of the program, 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. A scientist at NIDDK then used a mathematical computer model of human metabolism to calculate the diet and exercise changes underlying the observed body weight loss. Because the TV program was not designed to directly address how the exercise and diet interventions each contributed to the weight loss, the computer model simulated the results of diet alone and exercise alone to estimate their relative contributions. 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. In addition, the simulations 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. These findings suggest that a more moderate weight loss strategy, rather than the extreme lifestyle intervention depicted in “The Biggest Loser,” would be preferable for sustained weight loss in many people who are obese.