They say you should choose your friends wisely, and perhaps here's a good reason why. The people around you all day at work and at home may have a bigger influence on how healthy you are than you think.
The results of the researchers' study, which are being published in the International Journal of Behavioural Nutrition and Physical Activity, suggest it's all down to our need to fit in.
Having examined surveys on health behaviours involving more than 3,500 women living in Australia, the researchers discovered those who said they had friends who ate healthy food and who were surrounded by people who took regular exercise were also more likely to do the same.
And it works the other way round too. According to the researchers, women who said many of their friends ate fast food were more likely to eat less healthily themselves too.
It could be that we think behaving in the same way as our friends, neighbours and work colleagues makes us appear more socially desirable, the researchers explain.
Is this your experience where your friends and neighbours are concerned? Have you altered your eating or exercise habits to fit in with the people you socialise with?