Diet versus Exercise in “The Biggest Loser” Weight Loss Competition

The Biggest Loser television show is watched by millions of people worldwide. Obesity experts have criticized its portrayal of an unrealistic intervention that raises false expectations for weight loss. Here, I quantify the diet and exercise intervention using a validated computational model of metabolism to integrate data on energy expenditure, body weight and body fat collected during The Biggest Loser competition.Participant age, body mass index, weight, and percent body fat at baseline were 33 ± 11 y, 48.7 ± 10.1 kg/m(2), 144.9 ± 39.4 kg, and 49 ± 6 % (mean ± SD), respectively. During the first phase of the competition when the contestants were isolated in a boot camp environment, the average rate of weight loss was 0.4 ± 0.1 kg/d which decreased to 0.19 ± 0.1 kg/d after returning home for the final phase. The total weight loss was 58.2 ± 26 kg with 81.6 ± 8.4 % coming from body fat. The computer simulations closely matched the data and calculated that average energy intake during the first phase was 1300 kcal/d while participating in 3.1 h/d of vigorous exercise. After returning home, energy intake increased to 1900 kcal/d and vigorous exercise decreased to 1.1 h/d. Simulation of diet alone resulted in 34 kg of weight loss with 65% coming from body fat, whereas exercise alone resulted in a loss of 27 kg with 102% from fat. Simulated weight loss maintenance could be achieved with a modest 20 min/d of vigorous exercise and a 3000 kcal/d diet.