Patients who are considering obesity treatment may find they can turn to their own friends and family for first-hand experience, as new research suggests that social factors are involved in the development of obesity.
A study by researchers at Harvard Medical School and the University of California, San Diego, found that people with an obese friend are 57 per cent more likely to be obese themselves.
Having an obese sibling increases the likelihood by 40 per cent, while having a severely overweight spouse boosts a person's chances of being obese by 37 per cent, the report in the New England Journal of Medicine reveals.
Experts claim that social factors, such as the body sizes of surrounding people, are important in developing obesity as, apart from sharing a similar lifestyle, people's perception of 'normal weight' may be altered.
Study author Professor Nicholas Christakis explained: "It's not that obese or non-obese people simply find other similar people to hang out with.
"People come to think that it is OK to be bigger since those around them are bigger, and this sensibility spreads."