Weight Loss and Caloric Intake after Regular and Extended Gastric Bypass

The morbidly obese and especially the super-morbidly obese (>225% ideal body weight) often require gastric bypass surgery as treatment for long-term remission of their obesity. The extended gastric bypass Roux-en-Y (X-GBP) procedure evolved as a result of a perceived need to increase weight loss in morbidly obese subjects beyond the limitations of the regular gastric bypass Roux-en-Y (R-GBP). We compared weight loss, caloric intake, and percentage of total caloric intake from carbohydrate, protein, and fat in eight R-GBP and eight X-GBP patients at 3, 6, 9, and 12 months following surgery. We found that R-GBP and X-GBP groups were similar in age and height, adjusting for baseline weight differences (p = 0.122). Both groups demonstrated significant weight loss over time (p<0.0001), with similar patterns of weight loss at each interval of nonsignificant interaction (p = 0.585). Weight loss for the two groups did not differ statistically. The X-GBP group lost 5% more weight than the R-GBP group by 12 months following surgery. The adjusted average weight loss over 12 months was 56.82 kg for X-GBP and 46.82 kg for R-GBP patients. Furthermore, the X-GBP group ingested fewer calories than the R-GBP group at 3, 6, 9, and 12 months following surgery. The X-GBP group ingested a lower percentage of calories from fat than the R-GBP group at 3, 9, and 12 months following surgery. This study depicts clinical trends in weight loss following X-GBP and R-GBP surgeries. The greater weight loss of the X-GBP group may be due to differences in total caloric intake or the lower perventage of calories ingested from fat. Other possibilities for the greater weight loss shown by the X-GBP group may include changes in malabsorption or resting energy expenditure over time following surgery.