Collateral weight loss in children living with adult bariatric surgery patients: A case control study

Objective: To evaluate the impact of adult bariatric surgery on the body mass index (BMI) of children living in the same household. Methods: A retrospective case-control study. Case dyads (n = 128) were composed of one adult who had bariatric surgery and one child at the same address. Control dyads (n = 384) were composed of an adult with obesity but no bariatric surgery and a child at the same address. Two-sample t-test was used to determine whether the differences between actual and expected BMI at follow-up (post-surgery) differed between children in the case and control dyads. Results: Among boys who were overweight, boys who lived with a surgery patient had a lower than expected BMI post-surgery, while boys who did not live with a surgery patient had a higher than expected BMI at follow-up (P = 0.045). Differences between actual and expected BMIs of children were not significantly different between cases and controls in girls or in children in other weight classes. Conclusions: Overweight boys who lived with an adult bariatric surgery patient had a lower than expected BMI after surgery as compared to controls. Future studies may be warranted to determine the mechanisms by which these children experience collateral weight loss.