Marriage can boost your health in a number of ways but it appears there is one measure where it lets you down - your waistline.
Researchers have found that the average husband and wife pile on about 2kg each, suggesting that being hitched is not quite as healthy a lifestyle as previously believed.
Significantly, single people do more sport than than their married counterparts.
The study, involving nine countries, revealed that the average BMI (body mass index) for a single male was 25.7, while for their married counterparts it was 26.3. For women, the average was 25.1 and 25.6 respectively.
That equates to a difference of about 2kgfor a woman of 5ft 5in or a man of 5ft 11in. And the figures across countries were remarkably similar, showing the phenomenon is universal.
According to the World Health Organisation, a healthy BMI is between 18.5 and 25.
Previous research has shown married people generally have better health and longer lives than those who are not in a long-term relationship, with some suggesting single men suffer because they do not have a partner to impress.
Other scientists have found that those who do not have a partner are more likely to skip breakfast, eat unhealthy meals on the go, work long hours and spend more time drinking at the pub.
But the latest findings - from research by the Max Planck Institute for Human Development in Berlin and the University of Basel - shows it does not apply to all health indicators. The researchers report that couples on average eat better than singles, but they also weigh significantly more and do less sport.
It also revealed that couples ate more organic food and bought less convenience food. Professor Jutta Mata, who took part in the study, said it indicated that they took more care with their diet.
He added that men in long-term relationships are much more likely "to eat more consciously and, in turn, probably more healthily". But it does not mean they are generally healthier. Professor Mata said: "Our findings indicate that couples are not healthier in every respect, as has previously been assumed."
The study - published in the journal Social Science & Medicine - involved more than 10,000 participants from Austria, France, Germany, Italy, the Netherlands, Poland, Russia and Spain, as well as Britain, and also looked at cohabiting couples.
The respondents were asked about their eating and exercise behaviours and attitudes in face-to-face interviews.
This approach is said to ensure higher data quality. People are more realistic when reporting on factors such as their weight if they are asked in person rather than, for example, by telephone.
- Daily Mail