Millions are losing weight using GLP-1 drugs. How do they affect relationships?

For Jennifer, who is 57, her weight was the main reason she believed she had problems. She felt it stopped her from being invited to parties and affected the physical connection with her husband, even though their marriage was otherwise strong. She often thought that if people excluded her, it was because they didn't like overweight people.

Jennifer had struggled with obesity since she was eight years old. In her thirties, she had surgery to reduce her stomach size, but she gained the weight back. Everything changed in 2023 when she started using Mounjaro, a popular weight-loss medication from the GLP-1 class. These drugs were originally designed to manage type 2 diabetes by controlling blood sugar and slowing digestion, which helps reduce appetite.

Now, millions worldwide are using GLP-1 medications for weight loss. In Australia, prescriptions have increased dramatically since 2020, and in the US, their use has more than quadrupled. Jennifer's husband initially worried about common side-effects like stomach pain, but they decided the potential benefits were worth the risk.

After three years on the medication, Jennifer has lost 40kg (88lb), and the drugs have helped her manage her weight, something she’d struggled with her entire life. She had hoped that losing weight would improve the minor issues in her relationship, but she is now dealing with unexpected consequences for her 30-year marriage, which neither she nor her husband anticipated. She mentioned that having five years of therapy before starting the medication prepared her for the significant psychological changes she experienced.

Doctors often inform patients about the known physical side-effects of GLP-1s, such as nausea, vomiting, diarrhoea, and constipation. However, their effects on romantic relationships are not as well-researched or understood. Some people have shared online in forums and support groups that they have noticed changes in their desire, sexual function, and emotional connection with their partners.

Early research suggests that GLP-1s might affect more than just hunger. According to Dr Terri-Lynne South, a doctor specialising in obesity medicine, these drugs can impact the brain's dopamine reward pathways. This mechanism might reduce the desire for things like alcohol, nicotine, and potentially sex. While evidence on sexual function is mixed, some studies indicate GLP-1s could improve testosterone levels, potentially benefiting sexual health. However, a 2025 analysis found many reports of sexual dysfunction, particularly in men taking these drugs.

A 2025 study showed that about 18% of participants felt their sexual desire increased on GLP-1s, while 16% reported a decrease. Dr South points out that it's important to determine if these changes are solely due to the medication, the weight loss itself, or other factors like age or hormonal changes. Major and rapid weight loss on its own can significantly impact relationships. A 2018 study found that people who underwent bariatric surgery were more likely to divorce or separate if they were in a couple, and more likely to start a new relationship if they were single.

Jennifer is unsure if the intimacy issues in her marriage are due to her age, the medication, or her new sense of self after her body transformation. She notes that now, strangers offer help like carrying her shopping, which never happened before. In professional settings, people make comments about overweight colleagues that surprise her. Her husband suggested couples therapy, noting that Jennifer hadn't become more physically affectionate after losing weight and had become, in his words, 'meaner'.

Jennifer acknowledges that because she's less afraid of her relationship ending, she might have higher expectations of her husband. Without her obesity to blame, she now sees that her marital problems were always a shared issue, but her weight was an easy explanation because she felt so bad about it. Relationship issues are complex and rarely caused by just one thing. Dr Mark Mellor, a doctor who prescribes GLP-1s, suggests that increased self-confidence from weight loss might lead people to question their current relationships.

Psychologist Glenn Mackintosh observes that couples often experience disruption to their established routines after starting GLP-1s. For example, if sharing a snack like chips during an evening routine was a shared activity, this change impacts the relationship, creating a sense of loss. Increased self-confidence and attention from others can also create anxiety for partners, who may worry about their partner leaving them. Mackintosh believes these issues can be resolved through communication and acceptance in strong relationships. He emphasizes that weight loss doesn't create relationship problems but can bring existing ones to the surface.

The social challenges faced by people with obesity in dating are well-known. For some using GLP-1s, changes in their bodies can boost confidence for dating, but navigating psychological issues remains. After 14 years of being single, Joanna Wood started dating again at 59 after losing 25kg on a GLP-1. She felt nervous about her first date, partly due to shame about using the medication, viewing her past weight as a character flaw rather than a medical condition. Her date, Bruce Hart, was unfazed when she eventually told him, focusing more on her personality and values.

Dr Rebecca Puhl notes that some people hide their GLP-1 use, fearing partners might see it as lacking willpower. This can happen even though obesity is a recognised complex disease, and internalised weight stigma can persist. Wood experienced this shame despite her improved health. When she stopped the medication temporarily, she regained weight and struggled with cravings, hiding sweets from Hart. She has since restarted the medication, expecting to use it long-term. She is developing a program for women over 50 using GLP-1s to manage the psychological aspects.

Jennifer also expects to use her GLP-1 medication for life. Her marriage is another commitment she thought would last forever. She describes their situation as stable, with no fighting, but they are not actively resolving issues. She's uncertain if the medication changed her marriage or simply removed the excuse she had relied on for years. While the weight is gone, the underlying questions remain, and she knows they will eventually adapt, though she isn't sure how.