Women that go under the knife for weight loss surgery see improvements not just in their physical health, but in their sex lives too, a new study shows.

Writing in the Journal of the American Medical Association Surgery, University of Pennsylvania researcher David Sarwer and colleagues say they’ve found that after bariatric surgery, female patients score better on sexual functioning and desire. They also show improvements in the levels of various hormones associated with healthy sexual function.

“This is the first study I’m aware of that has a large sample size that looks at changes not only in self-reporting of sexual behavior, but also at the changes in hormones” associated with sexual functioning, Sarwer said in a phone interview.

Bariatric surgery can be any one of several procedures performed to help an obese person lose weight. The stomach may be shrunken by removing part of the organ or restricting it with a “lap bands”; or, a surgeon may do a gastric bypass where the stomach is divided into two pouches, with the small intestines hooked up to the smaller pouch. For this study, the researchers followed up with 106 women that underwent bariatric surgery. The average body-mass index of the participants before surgery was 44.5 -- a severely obese state that would equate to, for one example, carrying 292 pounds on a 5-foot-8 frame.

One year after surgery, the women had lost a third of their original weight, on average, which was generally maintained for another year. Two years after the surgery, the women reported significant improvements in many factors of their sex lives: desire, satisfaction, arousal and lubrication as well as improvements in the levels of sex hormones like testosterone, estradiol and follicle-stimulating hormone (FSH).

“What we were most pleased by was that those women that reported the greatest deficits in sexual function at baseline were the ones that showed the greatest improvement,” Sarwer says.

Sarwer and colleagues noted that other studies have shown improvements in a person’s mental quality of life after bariatric surgery. Interestingly, studies of people who have lost weight through lifestyle changes -- eating right and exercising -- show improvements in the physical domains of quality of life but not in the mental domains.

“This may be because the weight losses [with lifestyle changes] are relatively modest, and while patients are sometimes satisfied, they may not be experiencing profound psychological improvements” that come with the dramatic weight reductions seen with surgery, Sarwer says.

While this improved sex life may be beneficial for many patients’ romantic relationships, a subset of the participants did start showing signs of dissatisfaction with their partners in the years after the surgery. According to Sarwer, these patients may have already been in dysfunctional relationships, and the increased self-esteem the patient experiences after surgery and weight loss makes them feel more able to leave an unsatisfying partner.

The study did not have a particularly diverse sample size. Almost all of the participants were white, and three-quarters reported some education beyond high school. Part of the reason behind the demographic bias is that a large portion of the study population came from the same hospital in North Dakota.

Sarwer points out that the patients that undergo bariatric surgery tend to be overwhelmingly white. Pervasive racial disparities in access to health insurance and personalized medical care is believed to be one reason minority women might not go for weight-loss surgery. 

The team recently finished a similar study in male weight-loss surgery patients, which they will be presenting at an obesity conference next week in Atlanta, Ga., and which they expect to publish in 2014.

SOURCE: Sarwer et al. “Changes in Sexual Functioning and Sex Hormone Levels in Women Following Bariatric Surgery.” Journal of the American Medical Association Surgery published online 4 November 2013.