A wedding ring might come with an unexpected and disproportionate side effect for men: weight gain. Scientists at the National Institute of Cardiology in Warsaw, Poland, have found that married men are 3.2 times more likely to be obese than their unmarried counterparts. The same effect, however, does not appear to hold for women.

To be presented at this year’s European Congress on Obesity in Málaga, Spain, the study analyzed the health data of 2,405 Polish adults, exploring how factors like marital status, age, and mental health intersect with weight gain. The results were striking: while marriage increased the odds of being overweight for both sexes—by 62% in men and 39% in women—the likelihood of obesity soared only for men. Being overweight means having more body weight than what’s considered the healthy weight range, while obesity is a chronic condition that represents a severe form of excess fat and weight.

The Weight of Marriage for Men

What drives this difference among the sexes? Researchers point to societal expectations and lifestyle shifts. Married men may be more prone to weight gain due to larger portion sizes, social eating habits, and a decrease in physical activity.

“The main possible reasons are that single men looking for a partner have higher incentives and exert more effort to stay fit than those who are already or still married,” Joanna Syrda, a lecturer at the University of Bath told The Guardian.

Meanwhile, women often experience different pressures. Dr. Alicja Cicha-Mikołajczyk, one of the study’s authors, suggested that cultural stigmas surrounding women’s body weight could be a factor. “Women who are obese are more often stigmatized by society,” she said, proposing that women are more likely to take action against weight gain than men.

Marriage wasn’t the only factor influencing weight. The study found that with every passing year, the risk of being overweight increased by 3% in men and 4% in women, while the risk of obesity climbed by 4% in men and 6% in women.

Although the findings involve men and women from Poland, previous studies suggest a general trend across the world. A 2017 study found married American men had a higher body mass index (BMI) than their non-married counterparts, which equated to an extra 1.4kg (3lbs) on the scales. The same study found that men’s weight dropped before and after divorce. A study in China found male BMI increases for the first five years of marriage.

Other patterns emerged, particularly for women. Living in smaller communities—towns of fewer than 8,000 people—was linked to a higher risk of obesity, possibly due to limited access to healthy food options or fewer opportunities for exercise. Women with inadequate health literacy were 43% more likely to be obese, while those experiencing even borderline depression saw their obesity risk double.

“This study is yet another reminder that excess weight is driven by a complex mix of social, psychological and wider environmental factors—not simply personal choice,” said Katharine Jenner, director of the Obesity Health Alliance.

The research also highlights the importance of targeted health policies. “Instead of blaming individuals, we need policies that make healthy choices the easy choices—through better food environments, education, and support at every stage of life,” Jenner added.

Obesity is a global health crisis, with more than 2.5 billion people currently classified as overweight or obese. By 2050, more than half of all adults and a third of all children worldwide are projected to fall into this category. While the relationship between diet, exercise, and obesity is well understood, studies like this suggest that broader social structures—marriage, aging, and mental health—all play leading roles in shaping our health.