According to the study from North Carolina State University and the University of Texas at Austin, there can be a "dark side" to weight loss, if both partners are not on board with enacting healthy changes.
Lead author Dr. Lynsey Romo, an assistant professor of communication at NC State, said that 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.
For the study, researchers surveyed 21 couples - 42 adults - from across the country.
One partner in each couple lost 30 or more pounds in less than two years, with an average weight loss of about 60 pounds.
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 behaviours 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, 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.
The paper has been published in the journal Health Communication.