The Network Effect: Now Visible On Your Ass

Whether you are a size 4 or a 24 may depend on the friends you keep.

U.S. researchers have found evidence obesity is socially contagious and weight gain can spread from person to person through a social network in a domino effect.

The study, the first of its kind to look at how complex social environments affect obesity, revealed that a person's risk of gaining weight increases by 57 per cent if one of their friends becomes obese.