Loneliness isn’t good for anyone, but a new study shows that living alone is tied to a lower weight.

For this study, a Western Washington University researcher analyzed data from the National Longitudinal Study of Youth. Using data that goes back to 1979, sociologist Jay Teachman examined the living arrangements, changes in marital status and body weight of more than 3,000 participants.

He found evidence that marital status, as well as the change from “married” to “not married,” affect a person’s weight. His conclusion: Married people tend to weigh more than those who are single. The pattern held true among both men and women, according to the findings.

Interestingly, he also found that romantic partners who live together but are not married follow the same pattern.

So how does marriage or cohabitation affect weight? Either arrangement tends to increase body mass index, according to the findings. Even when the tendency to gain weight with age was considered, the effect remained. Still, the overall weight difference wasn’t significant: Married and cohabiting people weighed about three pounds more than singles, the researcher found.

Teachman has two theories that may explain the connection between living together and extra weight. One idea is what Teachman calls the appearance effect: Single people are lighter and more concerned about their appearance because they’re still in the dating market.
His other theory is that couples eat more often because they are constantly sharing enjoyable meals with their partners.

While a few extra pounds may be the downside of a committed relationship, there are also some benefits. Many other studies have found that marriage generally makes people healthier. So while your body may be a bit heavier if you’re in a relationship, it can also make your heart lighter.