A four-year study has suggested that in the short and long term, both partners are more contented if the woman has a lower Body Mass Index.
The researchers concluded that initially men stay in the relationship because they find their thinner partners attractive.
Further down the line, women feel confident and loved because they know their man still wants them.
The study from the University of Tennessee, which selected 169 married couples aged under 35, discovered that men who had a higher BMI, which is calculated from height and weight, were happier at the start of their marriage and stayed that way.
The same effect was true for the women – by the end of year four wives with a lower BMI than their husbands were significantly happier than those who weighed the same or more.
“The great message from our study is that women of any size can be happy in their relationships with the right partner,” the Daily Mail quoted lead author Andrea Meltzer, as saying.
“It’s relative weight that matters, not absolute weight. It’s not that they have to be small,” added Meltzer.
In pictures: Bend it like Mumbai yogini Natasha Noel
Photos: Varun, Taapsee, Jacqueline promote 'Judwaa 2' on 'Dance Plus 3'
Instagram's newest sensation: Check out these photos of Bruna Abdullah
Photos: This is how Chitrangda Singh looks without make-up
Photos: Malaika Arora parties wearing see-through lace dress