Abstracts
1998 Digestive Disease Week

#972

BODY COMPOSITION ASSESSMENT IN PATIENTS FOLLOWING GASTRIC BYPASS SURGERY FOR MORBID OBESITY. J.L. Sebastian. I. Yip, M. Flechtner-Mars, S. Uikema D. Heber and E.H. Livingston. Department of Surgery and Center for Human Nutrition, University of California, Los Angeles, School of Medicine, CA.

Objective: The success of obesity surgery is linked to setting a realistic end-point for post-operative weight loss. It is well known that traditional life tables underestimate final weights. The purpose of this study was to use Bioelectrical Impedance Analysis (BIA) to determine target weights pre-operatively.

Methods: We examined 28 patients (4 male, 24 female, age 21-57) who underwent Roux-en-Y gastric bypass surgery for morbid obesity at UCLA with pre-operative and post-operative BIA measurements. Body composition changes were determined for fat and lean body mass, as well as estimates for target weight and basal metabolic rate (BMR).

Results: Average pre-operative weight was 143.9 ± 24.8 kg with a body mass index of 50.4 ± 5.4 kg/m2. Following gastric bypass, the average loss of total body mass over a period ranging from 4 to 18 months (mean 11) was 46.3 ± 16.2 kg. Of this, 73% was from adipose tissue loss, with the remaining 27% from lean body mass reduction. The average BMR decreased from 2135 ± 327 kcal before surgery to 1793 ± 337 kcal after surgery. For the group as a whole, there was a 93% achievement of weight loss, as determined by pre-operative target weights, set by BIA.

Conclusion: Bioelectrical Impedance Analysis can provide valuable information regarding target weight determination for morbidly obese patients undergoing gastric bypass surgery. Importantly, our data demonstrates that there can be greater than ninety percent success rate in achieving this target weight through surgery. Results also suggest that the proportion of fat to lean body mass weight loss is similar to that obtained with conventional medical/dietary therapy. BIA may serve as a valuable tool in the integrated surgical-nutritional approach to managing morbidly obese patients, which may be important to the long-term success of weight loss following gastric bypass.

Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.