The long-held notion that a happy couple means a healthy couple may not translate to a thinner waistline. Researchers say couples who are satisfied with their marriage are more likely to gain weight compared to couples who are still trying to impress future partners by slimming down.

Lead researcher Andre L. Meltzer and her colleagues conducted a survey based study to establish the relationship between marital satisfaction and weight gain. The team analyzed four years of data from 169 newlywed couples in their first marriage.

Two times a year the couples were asked to report how content they were with the marriage, any stress they were feeling due to their relationship, and if they had any thoughts of divorce. Each spouse's weight and height were also recorded to determine their body mass index, BMI.

The research team concluded that fulfillment within the relationship was associated with a change in weight over time. Partners who were taking steps toward divorce were twice as likely to have lost weight — presumably in the hopes of attracting someone new.

"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 contrast, couples who were less satisfied in their relationship tended to gain less weight over time."

Meltzer went on to say the partner who loses the weight doesn't do so with the best intentions or through any actual health concern.

"Spouses who were less happy in their marriage were more likely to consider leaving their partner 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," she said.

The researchers urge couples to think about their weight in terms of their overall health rather than a means of attraction.

Meltzer said. "By focusing more on weight in terms of health implications as opposed to appearance implications, satisfied couples may be able to avoid potentially unhealthy weight gain over time in their marriages."

The study was funded by the National Institute of Mental Health, the Fetzer Institute and the National Institute of Child Health and Development. It was featured in the American Psychology Association's online journal Health Psychology.