Obesity might be contagious!

Everyone has a range of social networks and can be influenced in many ways by the appearance and behaviours of those around them.

Researchers in the US evaluated the networks of over 12,000 people who underwent repeated measurements over a 32 year period, to find out what influence social networks might have on weight gain and obesity.

Their results suggest that obesity can spread person-to-person through social networks in a quantifiable and distinct pattern that is dependent on the nature of the social ties.

Pairs of friends and siblings of the same sex had a stronger influence on each other’s weight gain than did those of the opposite sex. They believe this is because we are influenced more by those we resemble than those we don’t.

Spouses, despite sharing much of their physical environment, appear to have less influence on each other’s weight gain than mutual friends.

The researchers offer a number of hypotheses about how obesity might be ‘catching’. People’s views about the acceptability of being overweight can change if people within their social group gain weight; and their view of norms for weight may change.

Source: The New England Journal of Medicine, 26 July 2007