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. DESIGN AND 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. We used a two-sample t-test 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.