“Shacking up” has its implications on couples’ waistlines, according to a study, which found living together could cause women to pack on the pounds, while their male partners actually lose weight. A third of women surveyed said they ate more once they moved in with their partner, often gaining weight as a result. Simultaneously, a third of men responded their food intake lessened, and their diets were healthier, including more “womanly” foods such as yogurt and salad.

The study of 1,300 men and women was conducted by Centrum Multivitamins. It indicated poor nutritional awareness among U.K. men and women. The survey also found men and women often feed each other based on gender stereotypes—90 percent of women responded they were more likely to purchase meat when shopping for their partner.

“I think the majority of us struggle to really understand what’s nutritionally best for ourselves and our partners,” Centrum’s Helene Manga said. “This can mean we’re often not getting what we really need for our gender.”

Dieticians at Newcastle University found similar results when reviewing seven studies that examined men’s and women’s diets after moving in together. They discovered women were more likely to take up poor eating habits and gain weight, even while encouraging their mates to choose more healthy food options. The men studied generally benefited from their female partner’s input, eating more fruits and vegetables and less meat, and often lost weight.

“Couples who move in together should use the opportunity of the honeymoon period to make positive changes to their diet and lifestyle by working together and supporting each other,” study author Amelia Lake told the U.K.’s Weightloss Resources.

[Image via Shutterstock]