REDUCTION OF SLEEPING METABOLIC-RATE AFTER VERTICAL BANDED GASTROPLASTY

OBJECTIVE: To investigate whether long-term weight loss after vertical banded gastroplasty (VBG) results in a sustained reduction of sleepin g metabolic rate (SMR) as a persistent risk factor for weight regain. DESIGN: Longitudinal clinical intervention study of morbidly obese pat ients undergoing VBG. PATIENTS: Group I: Six patients in which body co mposition 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 (B M) was measured before VBG, and body composition and SMR were measured 98 +/- 30 months after VBG. MEASUREMENTS: Body composition was assess ed by deuterium dilution and hydrostatic weighing. SMR was measured (S MRm) in a respiration chamber and predicted (SMRp) based on body compo sition. RESULTS: In group I, fat mass and fat free mass decreased sign ificantly 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). SMR m 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 disproportiona l reduction of SMR may reflect the persistent susceptibility of the po stobese to weight regain.