Shane Desmond has been taking Wegovy only since the beginning of January, but he’s already noticing benefits. For one, he has dropped about 18 pounds from his starting weight. He’s eating less at mealtimes, and he’s not binging as much. He used to reach for cheese or ice cream in the evening, especially while watching TV. “But I just haven’t been feeling it,” he says.

There’s something else: His libido has improved. At 51, Desmond says it was normal for him to feel in the mood maybe once a week. Now, it’s almost daily. “It kind of took me by surprise,” he says, considering he usually experiences low libido in the winter. He says there have “definitely been some improvements” in his sex life with his husband.

Millions of Americans are now taking Ozempic, Wegovy, Mounjaro, and Zepbound—a class of drugs known as GLP-1 receptor agonists—to treat type 2 diabetes and obesity. The drugs not only help people lose weight, they’ve also been shown to improve heart health, reduce the risk of kidney disease, and treat sleep apnea. They may also be having an effect on people’s sex lives.

There’s not much research yet on the sexual side effects of GLP-1s, but researchers do know that obesity can negatively affect sexual health in people of all genders. “We see higher rates of sexual dysfunction in both men and women who have obesity,” says David B. Sarwer, director of the Center for Obesity Research and Education at Temple University’s College of Public Health.

Sarwer has studied the effects of obesity on sexual function and what happens when individuals undergo bariatric surgery for weight loss. He says there tends to be a relationship between the degree of obesity and the degree of dysfunction, or difficulty experiencing satisfaction from sexual activity. “The heavier people are, the more likely it is that they have a dysfunction,” he says.

The reasons are difficult to tease apart, however, because comorbidities associated with obesity, such as type 2 diabetes, hypertension, and cardiovascular disease, can also cause sexual dysfunction. These conditions can damage the blood vessels and create blood flow problems, leading to vaginal dryness or erectile dysfunction. On top of that, many of the medications used to treat these comorbidities—including metformin, beta-blockers, and diuretics—can lower sex drive.

People with obesity can also have a higher psychosocial burden. Societal pressures and weight-shaming can cause low self-esteem, negative body image, and poor quality of life. These issues can lead to decreased sexual desire and feeling generally dissatisfied about sex. “It can be hard at the individual level to glean what exactly it is that is driving the sexual dysfunction,” Sarwer says.

One study Sarwer conducted followed 106 women who lost an average of 33 percent of their body weight after undergoing bariatric surgery. Two years after surgery, women reported significant improvements in desire, arousal, and overall sexual satisfaction. Those who reported the poorest quality of sexual functioning before surgery had the most dramatic improvements a year after. Participants also had changes in hormone levels, including lower testosterone and estradiol. High levels of these hormones can hinder sex drive and fertility.

When it comes to erectile dysfunction, sleep is often an overlooked factor, says Petar Bajic, director of men’s health at the Cleveland Clinic’s Glickman Urological Institute. Testosterone is made during deep sleep, and low testosterone is sometimes the culprit for a low sex drive.

“People who are heavier are more likely to have sleep disorders like sleep apnea, and if you have sleep apnea, you don’t get the deep and restful stages of sleep,” he says. “Your oxygen levels are dropping, and it prevents you from going into REM sleep, which is the deep and restful stage of sleep during which testosterone is produced.”

Zepbound, made by Eli Lilly, was approved by the US Food and Drug Administration in December as the first medication to treat obstructive sleep apnea.

The modest amount of weight Desmond has lost on Wegovy so far probably doesn’t explain his recent boost in libido. But the fact that he’s eating less may have something to do with it. “When I overeat, I’m out of the game for a couple hours. I just feel gross. My body’s digesting,” he says. “I’m sure that could have an effect on libido and our ability to do sexual things that require activity.” Most of us don’t feel particularly attractive after eating a large meal.

For Julie, who didn’t want her last name used for privacy reasons, GLP-1 medications haven’t changed her libido but have had a positive effect on her sex life in a different way. The 47-year-old started Wegovy in March 2023 and switched to Zepbound in August last year. Her “food noise,” or inner chatter about eating, has also decreased, and she has lost about 60 pounds, down from a starting weight of 276.

The weight loss has made her feel more physically comfortable in the bedroom, making sex with her husband more enjoyable. “If I’m on top, and I have weight resting on my knees or hips, it doesn’t hurt as much,” she says. “If I’m on all fours, my wrists don’t hurt from holding myself up, which makes everything better.”

Certain positions are quite literally a better fit now, she says. And the weight loss has made her more open to trying or suggesting those positions.

The reality is, sex drive and sexual interactions are complicated, says Jessica Borelli, a clinical psychologist at UC Irvine, who focuses on the links between close relationships, emotions, health, and development. They are in part determined by arousal, which has a physiological component, but also by relationship dynamics and psychological factors, she says. And of course, physical comfort during sex plays a role.

Borelli says that when people lose weight, they may feel more confident about themselves or have higher energy levels. But they may also be viewed or treated differently by their partners and others, especially if there’s substantial weight loss. For instance, they may be sexualized or objectified in a way they’re not used to. “People aren’t always ready for how that’s going to feel,” Borelli says.

Weight loss can change relationship dynamics in other ways. If one partner has lost weight and the other hasn’t, that could cause insecurity in the other person if they also want to lose weight. A person’s preferences in hobbies and interests can also change after weight loss, which can disrupt the typical patterns and rhythms of a relationship. For instance, if the person who lost weight is suddenly motivated to exercise more or forgo alcohol when they used to have lazy weekends with their partner or drink together as a couple, that could create tension.

GLP-1s may actually have negative effects for some people. A study published in May 2024 found that men with obesity who were taking semaglutide, the active ingredient in Ozempic and Wegovy, were actually at a slightly higher risk of erectile dysfunction than men with obesity who weren’t taking the drug. The reason for this isn’t known, and the authors concluded that further research needs to be done to “understand possible underlying biologic pathways that result in sexual dysfunction side effects.”

For Hannah, who asked to go by her first name only, her libido dropped dramatically after starting on Wegovy 10 months ago. In that time, she has exceeded her weight-loss goal, shedding about 75 pounds from her starting weight of 200. At 42, she says she was starting to feel a dip in her libido due to perimenopause before going on Wegovy, but now she hardly thinks about sex at all.

She doesn’t want to go off the medication, because she’s afraid the weight will return. But she’s conscious of the effect that her low sex drive might be having on her partner, who underwent gastric bypass surgery a few years ago and has experienced an increase in libido. “I worry that it’s going to affect her self-esteem,” she says. She says she’s still attracted to her partner, but she feels less engaged during sex now.

She wonders if her low libido is related to the fact that GLP-1s act on the brain. In addition to slowing the movement of food through the stomach to promote a feeling of fullness, the drugs interact with receptors in the brain to tamp down the desire for food.

Intriguingly, there’s growing evidence that GLP-1s may also reduce alcohol consumption and opioid use, suggesting the drugs may affect the brain’s reward system more broadly.

“When you think about it, it lowers drive, period. It lowers drive to eat. It lowers drive to drink alcohol, and it may actually reduce drive to have sex,” says Stephanie Faubion, director of the Mayo Clinic’s Center for Women’s Health. “I think that jury is still out.”

It’s possible that GLP-1s are affecting the brain and body in ways that researchers don’t yet fully understand. Only after larger studies are done will we be able to unravel how they might affect sexual function and desire.

“The body is very smart and very complicated,” Faubion says. “It’s almost certain that this receptor does something else.”