Opinion: I’m a weight-loss doctor. Here’s why I worry about GLP-1 ‘microdoses’

OpinionFirst Opinion I’m a weight-loss doctor. Here’s why I worry about GLP-1 ‘microdoses’ Tiny doses, big unknowns Manage alerts for this article Email this article Share this article By Jody DushayMay 29, 2026 Dushay is an assistant professor of medicine at Harvard Medical School and an attending endocrinologist at Beth Israel Deaconess Medical Center. Microdosing GLP-1s for cosmetic weight loss: Patients are asking me about it, TV and online ads are promoting it, friends are speculating about who’s doing it. But as someone who prescribes only legitimate GLP-1 therapies to people with obesity and weight-related metabolic diseases, I need to say this: Microdosing GLP-1s is not a thing. There are no legitimate long-term data to support it. In fact, there isn’t even a single definition of microdosing for weight loss or any other condition.Advertisement To explain, we have to start in the weeds. For weight loss, name-brand semaglutide (Wegovy) comes in six FDA-approved doses for weekly injection (0.25, 0.5, 1, 1.7, 2.4, and 7.2 mg) and four FDA-approved oral doses for daily ingestion (1.5, 4, 9, and 25 mg). Tirzepatide (Zepbound) comes in six FDA-approved doses (2.5, 5, 7.5, 10, 12.5, and 15 mg) for weekly injection. These are the only doses that have been studied rigorously for safety and efficacy. They all raise GLP-1 to pharmacologic levels that are far above what our bodies make. Wegovy injections are done with a single-use auto injector, while Zepbound is available as a single-use auto injector, in a single-use vial that is administered via syringe, or in a new device called a KwikPen that can deliver several doses before it is discarded. Unlike insulin vials, Zepbound vials do not contain preservatives, so they should be punctured only once, not repeatedly, then discarded. Ozempic, which is also semaglutide, comes in a multidose pen, too. Advertisement In the landmark, large clinical studies of both semaglutide and tirzepatide for weight loss, participants took 1.7 or 2.4 mg of semaglutide and 5, 10, or 15 mg of tirzepatide. These are also the doses studied and approved for prevention of secondary cardiovascular events and metabolic dysfunction-associated steatotic liver disease (semaglutide) and for sleep apnea (tirzepatide). Getting into the details of dosing and devices that administer the medication is important: FDA-approved doses should be increased only under the ongoing supervision of the prescribing medical professional. The multidose Ozempic and Zepbound pens actually do allow for dosing flexibility. By “counting the clicks” on the pen’s dial, you can administer doses that fall between standard doses. I might suggest this approach to a patient who is having difficulty with side effects, or someone who is having brisk weight loss on low doses. This is individualizing dosing under close medical supervision to address specific clinical situations. I would not call this microdosing. Another scenario is a patient who has been using a GLP-1 therapy for a few years, has reached a weight-loss plateau, and is now in the maintenance phase of treatment. We may try spreading out the number of days between doses from weekly to, say, every 10 days. I would not call this microdosing, either. In both cases, I am finding the optimal pharmacologic dose for ongoing treatment. These approaches are common among doctors who specialize in medical weight management, and as such, medical record data can be studied to inform future guidelines and standardization about maintenance-phase dosing in particular. What, then, is microdosing? The term has been popularized by direct-to-consumer companies that sell compounded products that are not FDA-approved GLP-1 therapies, at doses that are not based on legitimate, rigorous clinical studies. On social media, most of the microdosing chatter is about small amounts of weight loss, perceived (but not proven!) longevity benefits, and treating many forms of inflammation. It is very attractive to people who want just a little extra GLP-1 in their bodies, at a low price. Like the old advertisement for Brylcreem, a little dab’ll do ya!Advertisement But what will a small jab do to you? Long term, we don’t know. I tell all my patients that the list of unknowns for products used to microdose is long. Starting with the most worrisome, what exactly is in the product you are about to take? None of these compounded products have been studied either short or long term for safety, efficacy, or weight regain after stopping them. Because these products are sold in units that are different from the real medication, there is no way to convert dosing of a compounded product to a real GLP-1. Some medical clinics advertise microdosing Zepbound by drawing up less than the full amount in the single-use vial, but this has not been studied, and there is a risk of contaminating the vial by using it more than once. Although I am currently two thumbs down about microdosing compounded and fake GLP-1s for cosmetic weight loss or any medical condition, I am very excited about the weight-independent effects of GLP-1 treatment. People who have very little weight loss may still get real benefit for treating cardiovascular and liver disease, sleep apnea, and a range of inflammatory and neurological diseases. The art of tissue-specific and disease-specific dosing may emerge in the not-too-distant future: Rather than using the current pharmacologic doses of GLP-1s to soak receptors throughout the body, we may learn how to apply much more tailored brush strokes to effectively treat, say, dementia or rheumatoid arthritis. To get there, we need to systematically study smaller doses of real GLP-1 therapies in people with different conditions. Research in these areas is ongoing, but as was pointed out in a recent New York Times article, many people are not waiting for the data. They are giving it a (literal) shot with microdosing, often with minimal medical supervision. There’s no guarantee that these small doses won’t cause big problems. Jody Dushay, M.D., is an assistant professor of medicine at Harvard Medical School and an attending endocrinologist at Beth Israel Deaconess Medical Center.Advertisement Letter to the editor Have an opinion on this essay? 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