Energy expenditure, metabolic adaptation, physical activity and energy intake following weight loss: comparison between bariatric surgery and low-calorie diet.

OBJECTIVE

Bariatric surgery remains the most effective treatment to achieve substantial weight loss; however, total daily energy expenditure and physical activity changes in response to such interventions have been seldom explored.

METHODS

In this prospective observational study, total daily energy expenditure (TDEE) using doubly labeled water and physical activity (SenseWear armband) was assessed in 17 females (mean ± SD: 48.6 ± 9.7 kg/m2, 43 ± 12 years) at baseline and 8 and 52 weeks following either bariatric surgery (BSG, N = 9) or a low-calorie diet (LCD, N = 8). Energy intake was assessed using the intake-balance method.

RESULTS

After 8 weeks, weight loss was 16.0 ± 3.5 kg and TDEE decreased by 552 ± 319 kcal/d in BSG (P < 0.001) compared to 8.8 ± 3.4 kg and 256 ± 239 kcal/d in LCD (P < 0.05). After 52 weeks, weight loss was 44.3 ± 16.4 kg and TDEE decreased by 583 ± 418 kcal/d (P < 0.001), compared to 4.3 ± 6.7 kg and 84 ± 285 kcal/d in LCD (P > 0.05). TDEE was lower than predicted in BSG at 8 (P = 0.03) but not 52 weeks (P = 0.77). There was no evidence of metabolic adaptation in LCD. Average daily energy intake in BSG was 1403 ± 245 kcal/d compared to 2545 ± 398 kcal/d in LCD (P < 0.001). In BSG, step count and physical activity minutes were increased at 52 weeks compared to baseline (P = 0.03), whereas no significant changes were observed in LCD.

CONCLUSION

Bariatric surgery-induced weight loss decreased TDEE at 8 weeks and 1 year, resulting in metabolic adaptation after 8 weeks that was reversed at 1 year. These changes were accompanied by an increase in physical activity.