Body composition, dietary intake, and energy expenditure after laparoscopic Roux-en-Y gastric bypass and laparoscopic vertical banded gastroplasty: a randomized clinical trial.

Objective: To assess body composition, eating pattern, and basal metabolic rate in patients undergoing obesity surgery in a randomized trial.
Introduction: There is limited knowledge regarding how different bariatric surgical techniques function in terms of altering body composition, dietary intake, and basic metabolic rate.
Methods: Non-superobese patients were randomized to laparoscopic Roux-en-Y gastric bypass (LGBP, n = 37) or laparoscopic vertical banded gastroplasty (LVBG, n = 46). Anthropometry, dual-energy x-ray absorptiometry (DEXA), computed tomography (CT), indirect calorimetry, and reported dietary intake were registered prior to and 1 year after surgery.
Results: Follow-up rate was 97.6%. LGBP patients had significantly greater reduction of waist circumference and sagittal diameter compared with LVBG. DEXA demonstrated a larger reduction of body fat in all compartments after LGBP, especially at the trunk (P<0.001). CT demonstrated more reduction of the visceral fat (P=0.016). Patients were able to eat all types of food after LGBP, although about 30% claimed they avoided fats. LGBP patients decreased their proportion of dietary fat significantly more than those operated on with LVBG (P = 0.005), who consumed more sweet foods and avoided whole meat and vegetables. Lean tissue mass (LTM) was proportionally less reduced, especially in men, after LGBP. The decreases in BMR postoperatively reflected the lower body mass in a pattern that did not differ among the groups.
Conclusion: LGBP patients demonstrated better outcomes compared with LVBG patients in terms of body composition. Energy expenditure developed as expected postoperatively. A "steering" away from fatty foods after LGBP may be an important mechanism of action in gastric bypass.