CHANGES IN MEASURED RESTING ENERGY-EXPENDITURE AFTER ROUX-EN-Y GASTRIC BYPASS FOR CLINICALLY SEVERE OBESITY ARE NOT RELATED TO BYPASS LIMB-LENGTH

Background: Roux-en-Y gastric bypass (RYGB) for clinically severe obes ity (CSO) results in a 'paradoxical' response of the measured resting energy expenditure (MREE) in which the MREE remains within the predict ed range based upon the Harris-Benedict (HB) equation, despite a signi ficant decrease in caloric intake to 500-1000 kcal/day. The mechanism for this response is unknown. A study was undertaken to determine whet her the changes in MREE after RYGB are related to limb-length of the g astric bypass. Methods: A prospective clinical trial of varying limb-l engths based on body mass index (BMI) in patients having RYGB for CSO. The records of patients who underwent RYGB for CSO and had MREE measu red at baseline, 6 months and 12 months postoperation were reviewed. M REE was performed using a Med Graphics(R) CCM system after an overnigh t fast or at least 4 hours after a light meal, and a 30 minute rest in a supine position in a neutral environment, on the same day of the we ek between the hours of 10 a.m. and 4 p.m. Patients were selected for RYGB in accordance with NIM recommendations. RYGB was performed in a s tandardized fashion with the Roux limb-length varied as follows: (A) B MI less than or equal to 51 kg/m(2) - 75 cm limb (n = 20); (B) BMI les s than or equal to 51 kg/m(2) - 150 cm limb (n = 16); (C) BMI greater than or equal to 51 kg/m(2) - 150 cm limb (n = 18); or (D) BMI greater than or equal to 51 kg/m(2) - 250 cm limb (n = 6). Results: Data from 60 patients (nine male, 51 female; mean age 39 years; mean baseline B MI 51.5 +/- 10 kg/m(2); mean baseline weight 145 +/- 32 kg) were analy zed. There were no significant differences in MREE or percentage MB-pr edicted energy expenditure between the groups. Conclusions: These data suggest that the observed changes in MREE following RYGB for CSO are not related to the limb-length of the bypass. (C) 1998 Lippincott-Rave n Publishers.