One of my patients is a woman who is 34 and doesn’t plan to have children. She has lost 28 pounds on a GLP-1 medication, her blood sugar and insulin resistance have improved, her jeans slide on without the usual struggle, and everyone from her sister to her trainer keeps telling her how amazing she looks.
By almost every conventional measure, her treatment is working, except she barely wants sex anymore.
She used to be the one who initiated but now desire rarely crosses her mind, and when her partner drops a hint, she feels polite indifference rather than appetite, which confuses her, because she loves him, finds him attractive, and can’t locate the switch that got turned off.
There’s something else, too. She tracks her heart rate variability (HRV), a measure of the variation in time between heartbeats that offers a window into the autonomic nervous system, and since she started the medication her morning number has dropped by 30 percent.
She’s losing weight but her body is telling a more complicated story.
Did the medication cause these changes? We don’t know for sure. Low desire and a falling HRV have many possible explanations (too little food, broken sleep, psychological stress, other medications, shifts in health or in the relationship itself), and any one of them could be responsible, or several could be braided together.
Still, I’m hearing versions of her story often enough now that it concerns me. Women on GLP-1s often tell me they want sex less. Some say arousal takes longer to build or arrives muted, as though someone turned down the volume on sensation. And several have confided that their vagina feels looser. They describe a laxity, a sense that things aren’t as snug or as responsive as they were before the weight came off.
I don’t yet know how common this is, or why it happens. It’s motivated me to ask every woman on these medications about desire, arousal, sensation, and pelvic floor function, ideally before her first dose and again each time the dose climbs or we have a follow-up visit.
What I can tell you is that the published evidence is astonishingly thin. I haven’t found a single randomized trial that used a validated measure of female sexual function, such as the Female Sexual Function Index (FSFI), as an endpoint in women taking GLP-1s, and I haven’t found a single study that measured pelvic floor strength. A July 2026 review from Mayo Clinic concluded that these drugs may paradoxically suppress desire and arousal through dopamine- and serotonin-related pathways in the brain, even as the weight comes down, while acknowledging that systematic clinical evidence in women is lacking.[1]
In other words, what I’m seeing in my patients is biologically plausible, and nobody has bothered to measure it yet. That brings us to today’s topic and a question for you: If you’re on a GLP-1, are you noticing a change in desire? Sensation? Pelvic floor function? HRV?
The great thing about Substack is that we can collect real world evidence instead of waiting for the people who fund the GLP research to step in and discover the more complete picture of what these medications may be doing to us, beyond reducing food noise, improving metabolism, lowering inflammation, and potentially reducing cognitive decline. I get it that these are wins for many of us, but only if we all get full informed consent.
I’ve spent more than 30 years caring for women, and I was trained, like most physicians of my generation, to treat the doctor’s scale as a vital sign and every lost pound as a small victory. Here’s what three decades in the exam room have taught me about that training.
We’ve become extraordinarily good at measuring how much weight a woman loses. We’re much less interested in what else she might lose along the way.
As GLP-1 medications reshape the treatment of obesity and get prescribed for other indications like bulimia, addiction, and diabetes, and as more women start them every month, that imbalance deserves scrutiny.
Note: The opening case is a clinical scenario illustrating questions that deserve investigation, not proof that GLP-1 treatment caused these symptoms. The patterns I describe from my practice are clinical observations, not study data. I wish we had the study data.
Let me be clear: I’m not opposed to GLP-1 medications. Semaglutide, liraglutide, tirzepatide, and the other incretin-based therapies represent an enormous advance in metabolic medicine; they can produce substantial weight loss and better glycemic control, and certain agents have demonstrated cardiovascular and other clinical benefits in appropriately selected populations. For women with obesity, type 2 diabetes, or significant metabolic dysfunction, they can be transformative. I’ve watched women fight insulin resistance for years with diet and exercise alone while their biology quietly worked against them, and I’ve seen how much changes, in their labs and in their faces, when that metabolic burden finally begins to lift.
So I want to ask a different question, one that sits underneath all the efficacy data: what should count as working, particularly for women?
Should a woman who loses 25 pounds while her strength slips, her HRV stays persistently low, and her desire fades be considered an uncomplicated treatment success? The answer depends on why those changes occurred, whether they last, and how they affect the life she’s trying to live, and yet those outcomes rarely make it into the conversation about weight-loss medications at all.
A 2025 review in Endocrinology took up the differences between women and men in how they respond to these drugs. Its authors, Stina Börchers and Karolina Skibicka, described quantitative differences in weight-loss response and possible interactions between GLP-1 signaling and estrogen, which will make sense to any woman who has noticed her appetite shift across her cycle. Their other finding was less reassuring: substantial gaps remain in the basic science involving women and female animals, especially research on brain function, behavior, and reproductive physiology.[2]
This is no small omission. These medications act on the pathways that govern appetite, metabolism, and reward, and the female hormonal environment, with its monthly tides and its midlife turn, may shape how those pathways respond. We’ve finally developed drugs that can bend the trajectory of metabolic disease. Now we owe the women taking them a full accounting of the consequences.
HRV is one of my favorite physiological measures, and one of the most misunderstood. It reflects the variation between successive heartbeats, and depending on how and when it’s measured, it offers a window into autonomic regulation, including the parasympathetic, vagal influences that let the heart slow down, settle, and recover. Higher HRV within the same person often tracks with better recovery and adaptability, though higher isn’t universally better; age, fitness, breathing, illness, medications, and measurement methods all push the number around, and I’m wary of anyone who turns a wearable score into a diagnosis.
Still, when a woman’s usual HRV drops substantially and stays down, I want to understand why, because the nervous system is where so much of a woman’s experience of her own body lives: her capacity to rest, to recover, to feel safe enough to soften into pleasure. GLP-1 medications may be part of that picture.
In a randomized, double-blind crossover trial published in Diabetes Care, 27 participants with type 2 diabetes and coronary artery disease received liraglutide or placebo. Compared with placebo, liraglutide:
• Reduced SDNN, a measure of HRV, by 33.9 milliseconds (P < 0.001).
• Reduced another HRV measure, RMSSD, by 0.3 log units (P = 0.025).
• Increased mean heart rate by 8.1 beats per minute (P = 0.003).
Those changes occurred even as weight and metabolic markers improved.[3] The finding deserves attention, though the participants looked nothing like a healthy 34-year-old woman, and the results can’t be stretched to cover every GLP-1 drug.
A newer study brought wearables into the picture. In 2025, researchers followed 66 people starting GLP-1 therapy for twelve weeks; participants lost roughly 10 percent of their body weight, and compared with matched controls, their resting heart rate rose by 3.2 beats per minute while their HRV ran 6.2 milliseconds lower at the twelve-week mark.[4] For someone whose baseline HRV is 60 milliseconds, six milliseconds may look trivial. For someone starting at 20, the same absolute drop takes a much bigger bite, which is why I care about a woman’s own baseline and trend far more than any universal target.
The evidence doesn’t all point one way, and I’d be doing you a disservice to pretend it does. In the large GRADE trial of adults with type 2 diabetes, liraglutide didn’t increase ECG-defined cardiovascular autonomic neuropathy relative to the comparison treatments, and one HRV measure, SDNN, was higher in the liraglutide group at two years (P = 0.02).[5] Meanwhile, a 2026 meta-analysis of randomized trials found that GLP-1-based medications raised resting heart rate overall, by about 3.5 beats per minute compared with placebo, with the size of the effect varying by agent and dose.[6]
Where does that leave us? Some GLP-1 medications can raise resting heart rate, and several studies show reductions in HRV, particularly early in treatment; but a lower reading doesn’t establish autonomic injury, and we don’t yet know the long-term meaning of every change we can observe.
A medication can improve cardiovascular outcomes while changing the autonomic signals your wearable measures, like resting heart rate and HRV.
What bothers me is how little sex-specific information we have. How much does HRV change in premenopausal women compared with postmenopausal women? Does estradiol status modify the response? Does the speed of weight loss matter more than the dose? And what happens to HRV when a woman is eating too little to support her training, a trap that’s easy to fall into when a drug has quieted hunger so effectively she forgets to eat lunch? These are answerable questions. For now, the studies I’ve described don’t give us reliable women-versus-men estimates of GLP-1-related HRV changes, so what we have is a research gap, and a gap is no evidence that the effect runs larger in women.
Of everything I’m raising here, this may be the least studied and the most personally consequential, and it’s the one I hear about most in my office. It also sits at the center of the work I care about most, because female desire has always behaved like the canary in the coal mine of women’s health: it’s often the first thing to dim when something in the body or the life goes wrong, and too often the last thing anyone in a white coat thinks to ask about.
One of the remarkable effects of GLP-1 medications is the lowering of what patients call food noise. Women describe walking past the refrigerator without a running internal debate about what’s inside it, sitting through a work lunch without counting bites, waking up without the morning bargain about what they will and won’t eat that day. For many, that silence feels like freedom. I get it. I’m in recovery from disordered eating and food addiction after suffering privately with it until age 40.
But food isn’t our only source of pleasure, and appetite was never only about food. GLP-1 receptors sit in the hypothalamus and in the mesolimbic reward circuits that drive “wanting,” the motivational pull toward food, sex, and other natural rewards, so the same mechanism that quiets the call of a second helping could plausibly quiet the pull toward sex.[1] Could medications that turn down food-related reward also turn down sexual desire? Possibly.
The July 2026 review in Menopause, led by Regina Castaneda and colleagues at Mayo Clinic, examined weight-loss interventions and sexual function in midlife women and described a paradox worth taking seriously. Obesity itself impairs female sexual function, and weight loss through lifestyle change or bariatric surgery tends to improve it, through better metabolic health, body image, mobility, and vascular function; so when women on GLP-1s report the opposite, weight loss alone can’t explain it. The authors proposed that these drugs may act on desire and arousal through central neuroendocrine pathways, including dopamine- and serotonin-related signaling, while emphasizing that clinical evidence in women remains limited, drawn mostly from case reports, preclinical observations, and biological hypotheses rather than large, well-controlled human trials. Their practical recommendation is one I endorse: assess sexual function with validated instruments before and during therapy.[1]
In February 2026, researchers reported another intriguing finding in Behavioural Brain Research. They gave several GLP-1 receptor agonists to sexually experienced female rodents. In female rats, exendin-4 reduced proceptive behaviors (the darts and hops a female uses to solicit a mate) along with the intensity of lordosis, the posture of sexual receptivity; in female mice, liraglutide and dulaglutide reduced the time females spent with males. The researchers pointed to the lateral septum and the nucleus tractus solitarius, a brainstem hub, as likely sites of action, and the effects varied by drug and species.[7]
This doesn’t prove that Ozempic or Mounjaro lowers libido in women. A rat’s hop is a long way from a woman’s longing, which is woven from hormones, relationships, cognition, physical comfort, personal history, stress, and the felt sense of emotional safety. But the findings support a question that deserves proper human research.
And men? A 2025 analysis of the FDA Adverse Event Reporting System found a signal for decreased libido among men taking GLP-1 medications, though the picture isn’t uniform (some users report the opposite, a rise in libido), and databases like this one can’t establish that a drug causes a symptom or how often it occurs.[8] The drugs may not all behave alike, either. A 2026 analysis of real-world adverse-event reports found that tirzepatide had lower reporting odds than other GLP-1 medications for decreased libido (adjusted reporting odds ratio 0.39) and for sexual dysfunction (0.16).[9] That analysis wasn’t specific to women, and voluntary reporting databases carry well-known biases, so I treat it as a question worth testing, nothing more.
Then there’s sensation. Some of my patients tell me that touch feels muted, that arousal needs more stimulation to build and fades faster than it used to. I haven’t found any study of genital sensation in women on GLP-1s. The closest signal comes from a 2026 pharmacovigilance analysis of the World Health Organization’s global adverse-event database and the French national database, in which semaglutide and tirzepatide were associated with abnormal or heightened skin sensation (dysesthesia and hyperesthesia), while exenatide was associated with reduced sensation (hypoesthesia); the effects appeared dose-dependent, often resolved when the drug was stopped, and in some cases returned when it was restarted.[10] Extending those findings to the vulva and clitoris is speculative. It’s still a good reason to ask.
We currently lack a reliable percentage of women who experience reduced libido on GLP-1 therapy, or a trustworthy comparison with men.
I find that unacceptable as these drugs move from short courses toward long-term use. If sexual desire were a routine, predefined outcome in GLP-1 trials, we would already know whether these medications improve it, suppress it, or do both in different groups of women, and whether the answer shifts with menopausal status, the amount of weight lost, the type of drug, the dose, or the energy a woman has left after a day of eating very little. Instead we have a system that carefully records nausea and constipation and ra…
