Preferential loss of central (trunk) adiposity in adolescents and young adults after laparoscopic gastric bypass

Background: An increasing number of young people are developing severe obesity with adult-like co-morbidities and undergoing bariatric surgery. Although a number of studies have described major weight loss after bariatric surgery, none have examined the proportions of lean body and fat mass lost or the potentially more important issue of changes in regional fat mass distribution after laparoscopic gastric bypass surgery. Methods: Five morbidly obese females (mean age 18) were evaluated by standard anthropometric measures and dual energy x-ray absorptiometry at baseline and 1 year after bariatric surgery. The mean and SD values for the anthropometric and dual energy x-ray absorptiometry body composition variables were calculated, and the differences were evaluated using paired t tests. Results: Significant body mass index and weight loss were seen in all subjects at 1 year, with the percentage of excess weight loss at 63.4%. Overall fat mass loss exceeded lean mass loss by threefold in this cohort (P <.01), demonstrating the relative sparing of lean mass. Their waist circumference also decreased significantly. Using dual energy x-ray absorptiometry analysis, the vast majority (83%) of central mass loss consisted of adipose tissue. Central fat loss significantly exceeded peripheral fat loss by 1.6-fold (P = .03). Conclusion: These results have demonstrated the preferential loss of central adiposity in morbidly obese young women after 1 year of surgical weight loss and may be more informative than anthropometric measurements alone. Given the association between central adiposity and the risk of subsequent cardiovascular disease, these results are suggestive of reduced cardiac risk.