Weight Loss Composition: The Effects of Exercise following Obesity Surgery as Measured by Bioelectrical Impedance Analysis

Background: Sudden weight loss following bariatric operations for morbid obesity, such as the duodenal switch (DS), can result in a concurrent decrease in lean body mass. Several methods for tracking body composition, such as bioelectrical impedance analysis (BIA), are available to monitor these changes. One method to offset the negative effects of sudden weight loss on body mass composition may be exercise. Methods: 100 patients who had undergone the DS operation for morbid obesity were classified as exercisers and non-exercisers based on self-reporting. Their body mass compositions were measured using BIA preoperatively and at 0.75, 1.5, 3, 6, 9, 12, and 18 months postoperatively. Results: At no study interval did postoperative percent changes in weight loss differ between the exercise and non-exercise groups. At 18 months postoperatively, the exercise group showed a 28% higher loss of fat mass and an 8% higher gain in lean body mass than the non-exercise group. Conclusion: Exercise positively influences body mass composition following the DS. BIA can be successfully employed to monitor changes, diagnose deficiencies, and formulate treatment recommendations.