Researchers from the Southern Methodist University in Dallas studied 169 newly married couples over four years. They measured their weight and asked them how satisfied they were in their relationship eight times.
They found that spouses who were happy in their union tended to gain more weight while those who weren't so satisfied tended to gain less weight.
The findings held even after compensating for factors such as pregnancy, the 'Daily Mail' reported.
"For each unit of increase in satisfaction found, either by the person or the partner, a 0.12 increase in BMI occurred every six months, on average," lead researcher Andrea Meltzer, said.
This increase would be equivalent to a 5ft 4in woman weighing 54 kg gaining half a pound every six months. Although the weight gain period wasn't great it could add up over a longer period of time.
"We don't know what happens after the four years yet," she told Health Day news.
Meltzer said that those in unhappy marriages may manage their weight better because they are contemplating divorce and want to attract a new partner.
However, she cautioned that her results do not prove a cause and effect link.
A recent study from Ohio University found wives tend to put on weight after tying the knot while men stay relatively trim.
Scientists, who tracked the lives and figures of more than 10,000 husbands and wives suggested this was because women stop taking care of themselves to look after their husbands when they get married. This could explain why men in the study generally gained weight if they split with their partner.
"Clearly, the effect of marital transitions on weight changes differs by gender.
"Divorces for men, and to some extent, marriages for women, promote weight gains that may be large enough to pose a health risk," researcher Dmitry Tumin said.
