Weighting for Friends: Obesity spreads in social networks

Although a variety of personal traits influence weight gain, obesity is socially contagious, moving from person to person through networks of friends and relatives, a new investigation finds.

The study, the first to examine how social ties influence the development of obesity over time, finds that if one person becomes obese, others who know that person well have an increased risk of also becoming obese within the next 4 years.