Marriage triples men’s risk of obesity, but has no effect on women. Such is the shocking information revealed by the study.

Global obesity rates have more than doubled since 1990, with more than 2.5 billion adults and children classified as overweight or obese.

By 2050, more than half of adults and one-third of children worldwide are predicted to be overweight or obese.

Unhealthy eating habits, inactivity, genetics, environmental toxins and underlying health conditions are known to increase the risk. But scientists at the National Institute of Cardiology in Warsaw, Poland, wanted to study whether other factors were also relevant. The researchers used statistical analysis to determine the link between weight gain and age, marital status, mental health and other factors.

The study, presented at the European Congress on Obesity in Malaga, Spain, found that married men were 3.2 times more likely to be obese than single men, but there was no increase in the risk of obesity for married women. Marriage is said to increase the risk of being overweight by 62% for men and 39% for women.

A 2024 study conducted in China found that men’s BMI increased in the first five years after marriage due to lower calorie intake and less exercise. It found that married men were 5.2% more likely to be overweight and 2.5% more likely to be overweight for men. A previous study by the University of Bath found that married men were on average 1.4kg heavier than their unmarried counterparts.

The Warsaw study also found that age was a factor in weight gain. Each year of age increased the risk of being overweight by 3% for men and 4% for women, and the risk of obesity by 4% for men and 6% for women.

Scientists say some factors only affect the likelihood of obesity in women. Depression doubles women’s risk of obesity and increases health literacy by 43%, while obesity is more common in women from smaller communities. None of these factors increase men’s risk.

Katharine Jenner, director of the Obesity Health Alliance, said: “This study is yet another reminder that excess weight is driven by a complex mix of social, psychological and wider environmental factors – not just personal choices. Every year, the risk of living with overweight or obesity increases, especially for women. Meanwhile, the link between marriage and obesity in men highlights how lifestyle changes, habits and social expectations affect our health.”

The study also suggests that men may be more likely to gain weight after marriage due to factors such as increased meal sizes, social eating habits and reduced physical activity, while women are likely to be more conscious of their body weight due to social pressures.

It added, “Instead of blaming individuals, we need policies that make healthy choices easier – through improved food environments, education and support at every stage of life.”

Joanna Sirda, a lecturer in business economics at the University of Bath, said the Warsaw study “confirms what I found in 2017: men’s BMI increases after marriage and decreases just before and after divorce. The main possible reasons for this are that single men who are looking for a partner have greater incentives and make more effort to stay fit than those who are already married or still married. And secondly, those in relationships may eat more regular meals and/or richer foods due to social obligations, which may be due to marriage.”

Jim Pollard, a consultant at the Men’s Health Forum, cautioned against overinterpreting the results. He said that long working hours and stressful careers with unhealthy eating habits could contribute to increased BMI in married life.

The research also says, ‘Men are more likely to die prematurely from heart disease and cancer, and weight is a key factor in these conditions. We need a more targeted approach to tackling obesity in men and women. The government has committed to both a men’s health strategy and a women’s health strategy – this research shows how important it is to get them right.’