The effect of limb-length on weight loss after gastric bypass is controversial. Some studies have concluded longer bypasses increase weight loss while others have no effect of bypass length on weight loss. Review of the negative studies show generally small sample sizes and thus are likely to be at risk for a beta, type II error. The purpose of this study was to compare the effect of variable limb lengths in patient weight loss.
Methods: 3,309 patients underwent Mini-Gastric Bypass and completed 1 year of follow up. Bypass limb length was modified based on starting weight.
Results: Weight loss following surgery followed a logarithmic decline following surgery though the end of the first year and then leveled off (fig. 1.) Weight loss was directly related to bypass limb length (fig 1.) As limb length increased mean weight loss at 1, 3, 6 and 12 months increased linearly. Linear regression model (y=mx+b) was y = 8.1 kilograms * x + 9.6 kilograms, (Regression Coefficient: r = 0.98) i.e. the model predicts an increase 7.7 kilograms for every additional foot of bowel bypassed.
Conclusions: The present study is the largest study of limb length and weight loss after gastric bypass. The study demonstrates that every additional foot of bowel bypassed adds a mean of 7.7 kilograms to the expected one year weight loss.
Program Number: P060