Psychologist Andrea L. Meltzer, an assistant professor at Southern Methodist University in Dallas, said this weight gain could put the couples at increased risk for various health problems related to being overweight.
"On average, spouses who were more satisfied with their marriage were less likely to consider leaving their marriage, and they gained more weight over time," Meltzer said in a statement. "In contrast, couples who were less satisfied in their relationship tended to gain less weight over time."
Meltzer and her research team said the findings challenged the long-held notion that quality relationships are always beneficial to one's health.
Instead, they said, the findings suggested spouses satisfied in their marriage were less motivated to attract an alternative mate and as a result, satisfied spouses relax efforts to maintain their weight.
For four years, the newlyweds reported twice a year on their marital satisfaction and steps toward divorce. They also reported their height and weight, which was used to calculate their body mass indices.
The study found spouses who were less happy in their marriage were more likely to consider leaving their partner, Meltzer said, and on average gained less weight over time.
"So these findings suggest that people perhaps are thinking about their weight in terms of appearance rather than health," Meltzer said.
The findings were published in the journal Health Psychology