Objective To measure long-term changes in resting metabolic rate (RMR) and body composition in participants of The Biggest Loser competition. Methods Body composition was measured by dual energy X-ray absorptiometry and RMR was determined by indirect calorimetry at baseline, at the end of the 30 week competition, and 6 years later. Metabolic adaptation was defined as the residual RMR after adjusting for changes in body composition and age. Results Of the 16 Biggest Loser competitors originally investigated, 14 participated in this follow-up study. Weight loss at the end of the competition was (mean±SD) 58.3±24.9 kg (p<0.0001) and RMR decreased by 610±483 kcal/d (p=0.0004). After 6 years, 41.0±31.3 kg of the lost weight was regained (p=0.0002) while RMR was 704±427 kcal/d below baseline (p<0.0001) and metabolic adaptation was −499±207 kcal/d (p<0.0001). Weight regain was not significantly correlated with metabolic adaptation at the competition’s end (r=−0.1, p=0.75) but those subjects maintaining greater weight loss at 6 years also experienced greater concurrent metabolic slowing (r=0.59, p=0.025). Conclusions Metabolic adaptation persists over time and is likely a proportional, but incomplete, response to contemporaneous efforts to reduce body weight.

ObjectiveTo explore how physical activity (PA) and energy intake (EI) changes were related to weight loss and regain following the Biggest Loser competition.MethodsAt baseline, six weeks, 30 weeks, and six years after the competition we measured body composition via dual energy X-ray absorptiometry, resting energy expenditure using indirect calorimetry, and EI and PA using doubly labeled water.ResultsSix years after the competition, median weight loss in 14 Biggest Loser participants was 13%, with those maintaining greater weight loss (mean ± SE) of 24.9 ± 3.8% having increased PA by 160 ± 23% compared to a PA increase of 34 ± 25 % (p = 0.0033) in the weight regainers who were 1.1 ± 4.0% heavier than the pre-competition baseline. EI changes were similar between weight loss maintainers and regainers (−8.7 ± 5.6% vs −7.4± 2.7 %, respectively; p=0.83). Weight regain was inversely associated with absolute changes in PA (r= −0.82, p=0.0003) but not with changes in EI (r = −0.15, p=0.61). EI and PA changes explained 93% of the individual weight loss variability at six years.ConclusionsConsistent with previous reports, large persistent increases in physical activity may be required for long-term maintenance of lost weight.