Influence of Energy Balance on the Rate of Weight Loss Throughout One Year of Roux-en-Y Gastric Bypass: a Doubly Labeled Water Study

• Published in: Obesity surgery 2019-10, Vol.29 (10), p.3299-3308
• Main Authors: Novaes Ravelli, Michele, Schoeller, Dale A., Crisp, Alex Harley, Shriver, Timothy, Ferriolli, Eduardo, Ducatti, Carlos, Marques de Oliveira, Maria Rita
• Format: Article
• Language: English
• Subjects: Adult; Clinical trials; Deuterium Oxide; Energy; Energy Metabolism - physiology; Gastric Bypass; Gastrointestinal surgery; Humans; Longitudinal Studies; Medicine; Medicine & Public Health; Metabolism; Middle Aged; Obesity; Original Contributions; Surgery; Weight Loss - physiology; Young Adult
• ISSN: 0960-8923; 1708-0428
• DOI: 10.1007/s11695-019-03989-z

Objective To investigate the influence of changes in energy balance and body composition on the rate of weight loss throughout 1 year of Roux-en-Y gastric bypass. Methods Variables were collected pre-, 6, and 12 months (M) post-surgery from 18 women (BMI ≥ 40 and ≤ 50 kg m −2 , 20 to 45 years). Total energy expenditure (TEE m ), fat-free mass (FFM), and fat mass (FM) were measured by doubly labeled water. Self-reported energy intake (EI sr ) was obtained from three non-consecutive food diaries. Metabolic adaptation was assessed via deviations from TEE predictive equation, and the calculated energy intake (EI c ) via the sum of TEE and change in body stores. Results BMI significantly decreased (mean ± SD) from 45 ± 2 kg m −2 to 32 ± 3 kg m −2 at 6 M, and to 30 ± 3 kg m −2 at 12 M after surgery. The TEE m reduced significantly at both time points when compared with pre-surgery (6 M: − 612 ± 317 kcal day −1 ; 12 M: − 447 ± 516 kcal day −1 ). At 6 M, a metabolic adaptation was observed and the energy balance was − 1151 ± 195 kcal day −1 , while at 12 M it was − 332 ± 158 kcal day −1 . Changes in the values of TEE m were associated with changes in body weight at 12 M post-surgery. A significant underreporting was observed for EI sr (1057 ± 385 kcal day −1 ) vs. EI c (2083 ± 309 kcal day −1 ) at 12 M post-operative. Conclusion The higher rate of weight loss at 6 M post-surgery was a response to energy imbalance, which was caused by high restriction in energy intake even with the presence of metabolic adaptation at this time. The EI sr was not sufficiently accurate to assess the energy consumption of this population. Registration of Clinical Trials (Observational Study) Brazilian Clinical Trials Registry: RBR-8k5jsj. Universal Trial Number: U1111-1206-0858.