"People need to be aware that weight loss can change a relationship for better or worse, and that communication plays an important role in maintaining a healthy relationship," says Dr. Lynsey Romo, an assistant professor of communication at NC State and lead author of a paper on the research.

For the study, researchers surveyed 21 couples -- 42 adults -- from across the country. One partner in each couple had lost 30 or more pounds in less than two years, with an average weight loss of about 60 pounds. Reasons for the weight loss ranged from changes in diet and exercise to medical procedures. The questionnaires asked each member of the couple about the impact of the weight loss on their relationship.

The researchers found that, after weight loss, the couples' communication generally changed for the good. The partner who lost weight was more likely to talk about healthy behaviors and inspire his/her partner to maintain or enact a healthy lifestyle. Couples in which both partners were receptive to these healthy changes reported more positive interactions and increased physical and emotional intimacy.

However, in some cases, weight loss resulted in negative communication. Some partners who lost weight nagged their significant other to follow their lead, which caused tension in the relationship. Other partners who hadn't lost weight reported feeling threatened and insecure by their partner's weight loss. These participants were resistant to change in their relationships. They would make critical comments toward their significant other, be less interested in sex, or try to sabotage their partner with unhealthy food in order to derail their partner's efforts and prevent the partner -- and the relationship -- from changing.

"This study found that one partner's lifestyle change influenced the dynamic of couples' interaction in a variety of positive or negative ways, tipping the scale of romantic relationships in a potentially upward or downward direction," Romo says. "When both partners bought into the idea of healthy changes and were supportive of one another, weight loss appeared to bring people closer. When significant others resisted healthy changes and were not supportive of their partner's weight loss, the relationship suffered.

"This study should not dissuade anyone from losing excess weight, but it should encourage people to be aware of the potential pros and cons of weight loss on their relationship," Romo adds. "It is really important for the partner of someone trying to lose weight to be supportive of their significant other without feeling threatened by their health changes. This approach will help people lose weight without jeopardizing the quality of their relationship."

The paper, "Weighty Dynamics: Exploring Couples' Perceptions of Post-Weight-Loss Interaction," was published online Oct. 24 in the journal Health Communication, and was co-authored by Dr. René Dailey of the University of Texas.