Persistent metabolic adaptation 6 years after "The Biggest Loser" competition

Abstract

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/day (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/day below baseline (P < 0.0001) and metabolic adaptation was -499 ± 207 kcal/day (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.

Trial registration: ClinicalTrials.gov NCT02544009.

Figure 1

Daily body weight changes in the individual subjects (thin lines) and the mean weight change (thick line) over the 2 weeks prior to the follow-up measurements 6 years after the Biggest Loser competition.

Figure 2

Individual (●) and mean (gray rectangles) changes in body weight (A), fat-free mass (B), and fat mass (C) at the end of the 30 week Biggest Loser weight loss competition and after 6 years. Horizontal bars and corresponding p values indicate comparisons between 30 weeks and 6 years. * indicates p<0.05 compared to baseline.

Figure 3

Body fat mass changes accounted for the vast majority of weight loss at both the end of the 30 week competition (●) and 6 years later (○). All data points fell on the same curve indicating that there was no evidence for preferential body fat regain.

Figure 4

Individual (●) and mean (gray rectangles) changes in resting metabolic rate (A), and metabolic adaptation (B) at the end of the 30 week Biggest Loser weight loss competition and after 6 years. Horizontal bars and corresponding p values indicate comparisons between 30 weeks and 6 years. * indicates p<0.001 compared to baseline.

Figure 5

No significant associations were detected between metabolic adaptation at the end of the 30 week competition with percent weight gained since 30 weeks (A) or percent weight change versus baseline (B) at 6 years. Metabolic adaptation at 6 years was significantly associated with the percent weight gained since 30 weeks (C) or percent weight change versus baseline (D) at 6 years.