If your closest friend becomes obese your risk of obesity goes up dramatically, according to researchers. And it was not just a matter of the friends eating the same foods, because the relationship holds even if the friends are separated geographically. Your risk also goes up if you have a sibling or a spouse who becomes obese, though the effect is not as great as between best friends.
How might social relationships affect obesity? Researchers speculate that when a person who becomes obese is already a close mutual friend, a sibling, or a spouse, one may tend to perceive obesity as more acceptable than if the person is a total stranger. Close mutual friends may also influence a person’s eating habits, even if the friends are not always together.
The data also offer a clue for why many of the most successful weight-loss programs are those that offer peer support. By modifying a person’s social network to include people who are also trying to lose weight, one’s view of normal and acceptable begins to change. The bottom line is that obesity is not just a medical problem with genetic roots, but also a public health problem with social causes. Understanding obesity will require a full understanding of both.