Spending time with healthy peers might be the best way to stay fit.

The importance of social environmental influences on health-promoting behaviour such as physical activity and healthy eating has been increasingly recognised. To investigate associations between social norms and a range of physical activity and eating behaviour amongst women, researchers surveyed 3,610 American women aged between 18 and 46 years. The women who took part in the study were asked to rate how much they agreed with statements like "I often see other people walking in my neighbourhood" and "Lots of women I know eat fast food often".

It was found that physical activity and healthy eating behaviour were both strongly affected by social norms. Those women who moved in healthier circles were in turn more likely to eat well and get more exercise.

The findings suggest that healthy behaviour may be contagious. The potential to modify social norms as an intervention lever for promoting increased engagement in physical activity and healthy eating needs further investigation.