Semaglutide, the medicine in Ozempic and Wegovy, produced an average weight loss of about 15 percent in its main trial, and the headlines have not stopped since. What the headlines leave out is the spread. About 14 percent of people in that trial did not lose even 5 percent of their weight, nearly everyone stops losing at some point, and two thirds of the lost weight comes back within a year of stopping. If you are not losing weight on Ozempic or Wegovy, you are somewhere in that data, and the reasons are usually identifiable. This guide covers how long semaglutide takes to work, the most common reasons it seems to stop, what to check with your doctor, and the trials designed for people it has not helped enough.
How long does it take for Wegovy or Ozempic to work?
Longer than the ads suggest. Semaglutide is started at a low dose and raised roughly every four weeks, and the standard Wegovy maintenance dose of 2.4 mg is not reached until about 16 to 20 weeks in. Most people notice appetite changes within the first few weeks, but meaningful weight loss builds over months, and in the STEP 1 trial the weight curve kept falling for roughly a year before it leveled off. Ozempic, the same molecule approved for type 2 diabetes, tops out at a lower dose than Wegovy, which is one reason people prescribed it for weight often see smaller results. If you are still in the dose escalation phase, "not working yet" and "not working" are different things.
Why you may not be losing weight on semaglutide
You are still early or on a low dose. The medicine's effect is dose dependent; many people are held at a low dose for side effects and never reach the amount used in the trials.
You have hit the plateau. Weight loss on semaglutide is not linear. In both the one year and two year trials, loss slowed and then stopped, at around 15 to 17 percent on average, as the body adapted with a lower resting metabolism and stronger hunger signals. A plateau after a year is the drug working as expected, not failing.
The appetite effect has faded. Some people report that Ozempic stopped suppressing appetite after months. Tolerance to the fullness effect does occur, though the weight effect usually persists as long as the medicine continues.
Eating patterns adjusted around it. Liquid calories, alcohol, and grazing are the usual culprits, because the medicine reduces hunger, not the calories in what you choose.
Other medicines or conditions. Steroids, some antidepressants and antipsychotics, insulin, and beta blockers cause weight gain; untreated sleep apnea, thyroid problems, and PCOS slow loss.
The product itself. Compounded or online versions of semaglutide are not FDA approved, and the FDA has warned about dosing errors and products with the wrong ingredient. If you are not using a pharmacy dispensed brand, that is worth raising with your doctor.
You are a non responder. In STEP 1, 86 percent of people lost at least 5 percent and 14 percent did not. Genetics, gut hormone biology, and other factors that are not yet understood mean semaglutide simply does less for some people, which is precisely what the newer medicines in trials are trying to fix.
What doctors usually do next
Confirm the dose and timing, review medicines that fight weight loss, screen for sleep apnea and thyroid problems, and add structured support for eating and activity, which the main weight loss trials included. If the plateau has been reached, the conversation is often about maintenance rather than more loss, because stopping is where most people lose ground: in the STEP 1 extension, people regained two thirds of their weight loss within a year of stopping. Some doctors discuss switching to other medicines, such as tirzepatide, which produced larger average loss in its own trials. Two GLP-1 pills have also been approved: the Wegovy pill, which is semaglutide itself, in December 2025, and Lilly's Foundayo (orforglipron) in April 2026. None of these decisions is one to make alone, and this article is not a substitute for that conversation. Our weight loss treatment trials page explains what is approved and what is being tested.
Trials built for people semaglutide has not helped enough
This is a fast growing category, because the industry knows the numbers above. There are trials of medicines meant to hold weight after a GLP-1 has done its work, so the regain does not happen; trials of new pills for people who would rather not use injections; and trials of add on medicines for people with type 2 diabetes whose blood sugar is still not at goal on semaglutide or tirzepatide. Some newer weight loss trials exclude recent GLP-1 use, so read each listing, but the first two studies below are specifically for people already on these medicines, and the third is a pill study open to adults with obesity.
Studies recruiting now for exactly this situation
A Phase 2 trial of ALV-100 for maintaining weight loss enrolls adults 18 to 75 who have already lost at least 10 percent of their weight on a GLP-1 type medicine and want to keep it off, at 12 US sites. A Phase 2 trial of a new Lilly medicine enrolls adults with type 2 diabetes whose blood sugar is still not at goal on a stable dose of semaglutide or tirzepatide, at 25 US sites. A Phase 3 trial of ASC30, a once daily oral GLP-1, enrolls adults with obesity or overweight at 6 US sites recruiting now, for people who would like a pill rather than an injection. You do not need to have used semaglutide to join. Each listing states its own rules, and applying takes about 5 minutes.
Common questions
Why did Ozempic stop working? Most often it has not stopped; the weight has reached the plateau the trials also showed, after roughly a year. Appetite suppression can fade over time, eating patterns adjust, and other medicines or conditions can work against it. A prescriber can sort out which applies.
What percentage of people do not lose weight on Wegovy? In the pivotal trial, about 14 percent did not lose at least 5 percent of their weight at 68 weeks, and about 30 percent did not reach 10 percent. Response varies widely from person to person.
Does Ozempic work for weight loss if you do not have diabetes? The same molecule is approved for weight management as Wegovy, which comes in higher doses than Ozempic, up to 7.2 mg in the Wegovy HD version approved in March 2026. Ozempic itself is approved for type 2 diabetes, and its lower top dose is one reason results for weight can be smaller.
Can I join a weight loss trial if I am already on semaglutide? Some trials require you not to have used a GLP-1 recently, but a growing number are designed for people already on one, including maintenance studies and studies of add on medicines. The listing says which, and the study team coordinates any change with your prescriber; never stop a medicine to qualify without that conversation.
See weight loss treatment trials recruiting now
Browse open studies, filter by location, and apply in about 5 minutes: Weight Loss Treatment Clinical Trials