London, Jun 22 (IANS): Putting paid to the idea that married couples have better physical health because of increased social support, a new study has found that marriage actually makes men fatter, and the early days of fatherhood add to the problem.

The findings, published in the journal Social Science & Medicine, confirms the theory that people who are single but seeking marriage have more incentive to stay fit and make more effort than those who are married.

"It's useful for individuals to understand which social factors may influence weight gain, especially common ones such as marriage and parenthood, so that they can make informed decisions about their health and well-being," said Joanna Syrda from the University of Bath in England.

The study suggests that married men who want to avoid increases in Body Mass Index (BMI) should be mindful of their own changing motivation, behaviour and eating habits.

"Given major public health concerns about obesity, understanding more about the social science factors that can cause weight fluctuation is important," Syrda added.

The study of heterosexual couples in the US, between 1999 and 2013, used data from the Panel Study of Income Dynamics.

The researchers found that married men have a higher BMI than their non-married counterparts, adding approximately 1.4 kg to the scales.

There was no effect on male BMI if their wife became pregnant, but in the early years after childbirth men gained weight.

It takes the period just before and after divorce to register a dip in male BMI, the findings showed.

The study supports the theory that marriage leads to more social occasions involving richer foods, or more regular meals for men.