Marriage triples the risk of obesity for men, but does not affect women, according to research.
Global obesity rates have more than doubled since 1990, with more than 2.5 billion adults and children classed as being overweight or obese. Worldwide, more than half of adults and a third of children are predicted to be overweight or obese by 2050.
While poor diet, inactivity, genetics, environmental toxins and underlying health conditions are known to increase the risk, scientists at the National Institute of Cardiology in Warsaw, Poland, wanted to study whether other factors were also relevant.
The researchers examined the medical and general health data of 2,405 people with an average age of 50. Statistical analysis was used to ascertain links between increased body weight and age, marital status, mental health and other factors.
The study, presented at this year’s European Congress on Obesity in Málaga, Spain, found that married men were 3.2 times more likely to be obese than unmarried men, but there was no increase in obesity risk for married women. Marriage also increased the odds of being overweight by 62% in men and 39% in women.
The findings came after a study conducted in China in 2024 found that male BMI increases for the first five years after marriage, owing to higher calorie intake and less exercise. It found being married was associated with a 5.2% increase in men being overweight and a 2.5% rise in men being obese.
An earlier study by the University of Bath found that, on average, married men were 1.4kg heavier than their unmarried counterparts.
The Warsaw research found age was also a factor in weight gain, with each year of increased age increasing the risk of being overweight by 3% in men and 4% in women, and the risk of obesity by 4% in men and 6% in women.
Some factors appeared to affect the odds of obesity only in women, the scientists said. Being depressed doubled the risk of women being obese and inadequate health literacy increased it by 43%, while obesity was more common among women living in smaller communities. None of these factors increased men’s risk.
Katharine Jenner, the 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 simply personal choice. With each passing year, the risk of living with overweight or obesity increases, particularly for women. Meanwhile, the link between marriage and obesity in men highlights how lifestyle changes, habits, and societal expectations shape our health.
“The research also suggests that men may be more likely to gain weight after marriage due to factors like increased portion sizes, social eating, and a decline in physical activity, whereas women perhaps remain more conscious of body weight due to societal pressures.
“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.”
Joanna Syrda, a lecturer in business economics at the University of Bath, said the Warsaw study “confirms what I found in 2017: male BMI increases after marriage and decreases just before and after divorce. 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. And second, those in relationships may eat more regular meals and/or richer foods due to social obligations, which may arise because of marriage.”
Jim Pollard, a consultant at the Men’s Health Forum, cautioned against over-interpreting the results. He said increased BMI in marriage could be a result of stressful careers with long hours and unhealthy meals.
“Men are more likely to die prematurely of heart disease and cancer, and weight is a key factor in these conditions. We need a more targeted approach to tackling men’s and women’s obesity. The government has promised both a men’s health strategy and a women’s health strategy – this research shows how important it is to get them right.”
