Researchers claim both partners are more content if the woman has a lower Body Mass Index (BMI) than the man.
A four-year study found that relationships lasted longer if the woman felt more attractive and desirable than her other half.
But relationship experts have already dismissed the findings, insisting that size is not necessarily a key factor in a husband finding his wife attractive.
The study at the University of Tennessee selected 169 married couples under the age of 35 and asked them to fill in questionnaires every six months for four years.
The findings discovered that men with a higher BMI than their wives were happier at the start of their marriage and stayed that way.
Equally women with a lower BMI than their husbands were happier than those who weighed more.
The findings could perhaps shed some light on last week’s announcement that Jennifer Lopez, who is celebrated for her curvy figure, was splitting from her thinner husband Marc Anthony after seven years together.
One of the authors of the report Andrea Meltzer said: