Reduction of sleeping metabolic rate after vertical banded gastroplasty

Abstract

OBJECTIVE: To investigate whether long-term weight loss after vertical banded gastroplasty (VBG) results in a sustained reduction of sleeping metabolic rate (SMR) as a persistent risk factor for weight regain.

DESIGN: Longitudinal clinical intervention study of morbidly obese patients undergoing VBG.

PATIENTS: Group I: Six patients in which body composition and SMR were measured before and at 3, 6 and 12 months after VBG. Group II (long-term effect): nine patients in which body mass (BM) was measured before VBG, and body composition and SMR were measured 98±30 months after VBG.

MEASUREMENTS: Body composition was assessed by deuterium dilution and hydrostatic weighing. SMR was measured (SMRm) in a respiration chamber and predicted (SMRp) based on body composition.

RESULTS: In group I, fat mass and fat free mass decreased significantly after VBG (P<0.05). SMRm decreased from 11.1±1.8 (s.d.) MJ/d before VBG to 8.1±0.9 MJ/d (P<0.05) at 12 months after VBG. In group II at a mean of 98 months after VBG, the SMRm (6.9±0.7 MJ/d) was lower than the preoperative value of group I (P<0.05). SMRm was lower than SMRp at all intervals after VBG (P<0.05). The ratio measured vs predicted SMR was in group I: 1.02±0.05 before VBG, 0.91±0.08 at 12 months after VBG (P<0.05), and in group II: 0.94±0.08 at a mean of 98 months after VBG (P<0.05).

CONCLUSION: The reduction of SMR adjusted for body composition after VBG is sustained as long as weight loss is maintained. The sustained and disproportional reduction of SMR may reflect the persistent susceptibility of the postobese to weight regain.