Why Your Best Friend Might Be Your Worst Enemy

One of the biggest predictors or whether you will develop type 2 diabetes? Whether your friends have it.

As Type 2 diabetes begins to affect more and more millions worldwide, its causes are increasingly well known – like lack of activity, poor food choices, and genetic susceptibility. But there’s another, less obvious risk factor that scientists are only just beginning to dig into: the company you keep.

Alison L. Hill, a graduate student at Harvard’s Program for Evolutionary Dynamics, authored a study that shows that obese people have the potential to create a ripple effect among their non-obese peers. That’s because the more non-obese people an obese person comes into contact with, the greater the chance those people will become obese.

Hill and her colleagues based their findings on a model of obesity’s spread through social networks, which was similar to models used to trace the spread of infectious diseases like the flu.

 In fact, the average weight of your peer group is one of the biggest predictors of your own overall health. But the psychological reasons behind this are more complex than you might imagine.

#1. Obesity Loves Company

Dr Jon Walz, a family physician in Ashland, Kentucky, points to our innate human instinct to search out people who look and act like us. As he put it in a 2011 CNN article,

“People who are obese live with obese people. They find obese friends. Most (patients) don’t recognize how bad a lifestyle they have, how self-defeating a lifestyle is. They think that culture’s normal.”

To make matters worse, as human beings we have a difficult time with change, Walz continues. So when someone we love alters his or her lifestyle, we have a problem dealing with it — even if that transformation is positive.

“Deliberately or not, the family, the friends, the other people who are part of that individual’s culture will resist the change,” Walz says. “(They) will try to change them back to what the culture tolerates.”

#2. Killing Us With Kindness

Our peer group can often derail weight loss efforts through a misguided attempt to make us feel better about ourselves. When Josephine Bullock, 38, of Reading, PA, announced that she was trying to lose weight, her friends responded swiftly. “All I heard from them was that I was beautiful and amazing and I didn’t need to change a thing,” she said. “I appreciated the love, but the truth was I did need to change. And a real friend would be willing to tell me what I needed to hear.”

#3. Food Constitutes Fun

Often our overweight peer group spends a great deal of time socializing in ways that contribute to their weight, like eating out, snacking, cooking, and the like. Since we tend to eat more in a social situation, this becomes something of a vicious circle: we hang out with people more likely to want to eat as part of that experience, which in turn itself makes us overeat.

If you happen to be a people pleaser – which many of us are – then the effects are even worse.

A recent Time Magazine article highlights a study by Case Western Reserve University researchers which shows that people-pleasers tend to overeat in social settings in an effort to make other people feel more comfortable. They feel pressure to eat, whether they’re hungry or not, in order to feel part of a particular social event.

#4. Mirror, Mirror, At The Table

A study carried from the University of Birmingham found that people who dined with someone who was more overweight were at risk of putting on weight themselves. Researchers claimed that those who chose unhealthy dishes from menus could influence the food choices of all the people around the table. Even those who were trying to diet would subconsciously mimic the eating patterns of their companions, psychologists found.

#5. The New Normal

Last, one of the more obvious  – and troubling – explanations about why obesity seems to be social contagious is simply about social norming. In other words, a person’s idea of what is an appropriate body size is affected by the size of his or her friends or family.

At an American Heart Association conference in Atlanta, Columbia University researchers reported the preliminary results of a study that found that overweight mothers and children tend to underestimate their own — and each other’s — weight.

In an interview with CNN, the lead author of the study, Nicole E. Dumas, M.D., points out that “…a lot of their misperception has to do with the fact that overweight and obesity is becoming the norm.”

In another recent study, 3,665 children and adolescents in Quebec were given a series of silhouettes showing body sizes ranging from underweight to obese. When asked to describe their own body, nearly 70 percent of the overweight and obese children chose a slimmer silhouette. But, as Tara Parker-Pope of the NYTimes points out in her health blog, the researchers discovered that children with the heaviest parents and peers were far more likely to underestimate their weight than those with healthy-weight parents and friends. “When kids live in an environment in which they see, on a daily basis, parents or school peers who are overweight, they may develop inaccurate perceptions of what constitutes a healthy weight,” says Katerina Maximova, assistant professor of epidemiology at the University of Alberta. “Their own overweight seems normal by comparison.”