Is obesity contagious?

Evaluation of: Christakis N, Fowler J. The spread of obesity in a large social network over 32 years. N. Engl. J. Med. 357(4), 370-379 (2007). A recent article using longitudinal data from the Framingham Heart Study found that weight gain was similar between friends. The influence of friends was found to be stronger than that of siblings or spouses. If this association reflects an underlying relationship, it implies that social norms, shared experiences and similar environments might be more important in weight gain than underlying strict biologic or genetic factors. It may also imply that new intervention strategies that use social marketing or peer-group efforts to reduce obesity might lead to successful weight control. A goal should be to enlist the help of friends to assist people to keep from gaining weight. Given the high prevalence of obesity in the USA and elsewhere, this study provides an interesting alternative foundation for addressing this important public health concern.