The People Who Make You Fat

Who you’re in contact with may determine the size of your belly

We’ve all known the friend in need who’s no friend indeed. Or the relative who only speaks to you when it’s time to complain. Or the coworker who is quick to dismiss your ideas. Maybe you’re surrounded by them: the cranks, the users, the judgers, the blamers.

These toxic relationships may not just strain your patience or mental health. A new study that followed more than 3,000 adults in their 30s and 40s found that people saddled with burdensome “negative relationships” accumulated more belly fat over 15 years than those who didn’t. To define “negative”, the study volunteers were asked how often friends and family members made unfair demands, criticized, let them down, or just plain got on their nerves.

Previous studies have uncovered a link between poor social connections and obesity, but much of the data are just snapshots of one point in time and can’t say which came first, says lead scientist Kiarri Kershaw, Ph.D., of Northwestern University. Relationships could sour because a person becomes obese, not the other way around. But Kershaw’s research team tracked people over years, which gives a better sense of cause and effect.

In the American Journal of Epidemiology, the Northwestern researchers report that while everyone gained weight as they got older, the waistlines of people with stressful relationships ended up slightly larger overall. Doctors say fat that sits around your middle poses the greatest threat to the heart and diabetes risk.

Kershaw theorizes that one problem comes down to food. Strained relationships can cause stress, which may drive you to seek the comfort of junk food and alcohol, both of which add calories. Stress can also affect how your body metabolizes excess calories, says Briana Mezuk, Ph.D., of Virginia Commonwealth University, by triggering stress-response systems that make body fat more likely to end up in your abdomen. “Stress affects not just our emotions, but our biology,” she says.

But there’s good news, too. Just like bad connections might make you fat, healthy ones might keep you leaner. In the new study, people who reported more supportive relationships—relatives they can rely on, friends they can talk to—didn’t gain as much belly fat as their peers. “Supportive relationships could be stress buffering, and keep you from using coping mechanisms like eating,” says Kershaw. So if you find yourself in too much toxic company, consider whether your heart is worth the risk.