Good news for people living alone: A forthcoming paper shows that single adults — of any sexual orientation — are physically healthier when it comes to body mass index. The study, which appears in the January edition of the Journal of Family Issues, found that living without a partner — either divorced or never married — is associated with lower body weight. On the other hand, co-habiters and married people, whether male or female, had higher BMIs, a calculation of weight and height that studies have linked to chronic conditions such as diabetes, heart disease, some types of cancers, and, ultimately, higher rates of mortality.
Sociologist Jay Teachman of Western Washington University used 20 years of data from the 1979 National Longitudinal Study of Youth and more than 3,000 participants to examine body weight, marital status, and what he calls relationship “transitions” — that is, breakups. He tracked people’s BMIs from adolescence to middle age (between 39 and 42 years old) and found people experienced a short-term weight loss after divorce, which he believes is probably stress-induced. Generally, Teachman thinks, couples that live together are heavier because they’re more likely to share meals and cook together. “The divorce effect fades over time,” Teachman told Science of Us. “But the data show that ‘the appearance effect’ persists. Single people are thinner and likely more concerned about how they look because they are in the dating market.”
His research is a departure from some of the conventional wisdom that coupled people tend to be fitter — and adds a wrinkle to the numerous links between marriage and positive health outcomes. Although Teachman acknowledges a caveat in his work: The difference in body weight between a married and single individual was about three pounds at any point in time. However, at higher BMIs, a three-pound spread could push the average respondent into the obese category — and the individuals in this study were fairly young. Since the data cut at age 42, people still had a lot of potential weight-gaining decades ahead of them.
Teachman also discovered an alarming racial trend in the data: White women experienced the least rapid, while black women, whether single or married, had the most rapid weight gain. “White women and black women start off the same, but then black women put on weight faster. Men and women, though, appear to react to changes in marital status in a similar way,” said Teachman. So that trope that women are always more sensitive or place more value on their physical appearance, especially after a split? It may be all a myth, or at least more complicated than the notion that women care more about their bodies than men.