The honest average: what the trials actually show
On average, people in the pivotal trials lost roughly 10% to 21% of their starting body weight, depending on the drug and dose. The two most effective FDA-approved options are semaglutide 2.4 mg (Wegovy) and tirzepatide (Zepbound). In the STEP 1 trial, adults with obesity or overweight (without diabetes) lost an average of 14.9% of body weight over 68 weeks on semaglutide, versus 2.4% on placebo (Wilding, NEJM 2021). In SURMOUNT-1, tirzepatide averaged 15% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg over 72 weeks (Jastreboff, NEJM 2022).
These are group averages, not before-and-after photos. Photos on social media are self-selected — they show the best cases, not the typical one — and cannot be verified. A clinical-trial average, by contrast, is measured in every enrolled participant on a fixed schedule, which is why it is a far more honest picture of what to expect. This page is general education and not medical advice; only a licensed clinician can tell you what any medication might do for you.
Results by drug (trial-average table)
The table below shows the average percent body-weight change at the trial endpoint for each drug, with the trial name and duration. "Off-label" means the drug is FDA-approved for type 2 diabetes but is sometimes prescribed for weight loss at a clinician's discretion; its weight-loss data come from diabetes trials, where average loss is typically lower.
One structural detail matters: trials report two "estimands." The treatment-policy (or treatment-regimen) estimand counts everyone regardless of whether they stopped the drug — closer to real life. The efficacy (or trial-product) estimand estimates the effect if everyone had stayed on treatment — a best-case ceiling. Headlines often quote the higher efficacy number, so the same trial can be described two ways (for example, tirzepatide 15 mg is cited as both 20.9% and 22.5%).
The range is huge: your result may not be the average
Averages hide enormous individual variation. In STEP 1, about 86% of people lost at least 5% of body weight, roughly 69% lost at least 10%, about 50% lost at least 15%, and around 32% lost 20% or more — meaning a large minority lost far more than the 14.9% average, and some lost very little (Wilding, NEJM 2021). Tirzepatide skews higher: in SURMOUNT-1, up to 57% of people on the 15 mg dose lost 20% or more (Jastreboff, NEJM 2022).
Real-world data echo this spread. A 2026 multicenter study in Mayo Clinic Proceedings of 511 patients found 12-month losses averaging 16.6% for tirzepatide and 13.4% for semaglutide, but with standard deviations around 8 percentage points — so individual outcomes ranged from minimal to well over 25%. Researchers are actively studying why some people respond much more than others, including genetic and metabolic differences, but no test currently predicts your result reliably. Treat any single number as a midpoint, not a target.
Ozempic and Mounjaro: off-label, and usually less
Ozempic (semaglutide) and Mounjaro (tirzepatide) contain the same active molecules as Wegovy and Zepbound, but they are FDA-approved for type 2 diabetes, not weight loss. They are sometimes prescribed off-label for weight management. Two things typically make their average weight loss lower than the weight-loss brands.
First, dose: Ozempic's top approved dose is 2.0 mg, below Wegovy's 2.4 mg. Second, population: weight loss is consistently smaller in people with type 2 diabetes. In STEP 2, semaglutide 2.4 mg produced about 9.6% average loss over 68 weeks in people with diabetes (Davies, Lancet 2021) — notably less than the 14.9% seen in STEP 1 without diabetes. For tirzepatide, SURMOUNT-2 showed 12.8% (10 mg) and 14.7% (15 mg) over 72 weeks in people with diabetes (Garvey, Lancet 2023), versus 19.5% and 20.9% in SURMOUNT-1 without diabetes. Whether a drug is right or appropriate for you off-label is a decision only your prescriber can make.
Oral options: the new Wegovy pill and Rybelsus
For a long time GLP-1 weight-loss drugs were injection-only, but that changed. On December 22, 2025, the FDA approved the Wegovy pill — once-daily oral semaglutide 25 mg — as the first oral GLP-1 approved for weight management, with a US launch expected in early 2026 (Novo Nordisk, Dec 2025). In its OASIS 4 trial, people who adhered to treatment lost about 16.6% of body weight over 64 weeks, similar to the Wegovy injection, and about one in three lost 20% or more (Wharton et al., NEJM 2025).
Don't confuse this with Rybelsus, a lower-dose oral semaglutide (up to 14 mg) approved only for type 2 diabetes, not weight loss. Investigational oral pills from other manufacturers were also in late-stage trials as of 2026 but were not yet FDA-approved for weight loss at the time of writing. Availability, pricing, and suitability of any oral option should be confirmed with a licensed clinician and pharmacy.
The regain reality: what happens when you stop
The single most important thing before-and-after photos leave out is what happens after you stop. Obesity is managed as a chronic condition, and the trials are clear that weight tends to come back when the drug is withdrawn. In the STEP 4 trial, people who reached the full semaglutide dose and then switched to placebo regained weight steadily, gaining back about two-thirds of what they had lost over the next year, while those who stayed on semaglutide lost a further 7.9% (Rubino, JAMA 2021).
Tirzepatide shows the same pattern. In SURMOUNT-4, people lost about 20.9% during a 36-week lead-in, then those switched to placebo regained about 14% of body weight over 52 weeks, while those who continued lost an additional 5.5% (Aronne, JAMA 2024). A later analysis found roughly 82% of people who stopped regained at least a quarter of the weight they had lost within a year, and cardiometabolic gains (blood pressure, blood sugar, cholesterol) partly reversed alongside the regain. None of this means you should keep taking or stop a medication — that is a decision for you and your prescriber — but it reframes results as something maintained, not a one-time event.
What affects your results
Beyond the drug and dose, several factors are associated with how much weight people lose. This is general information drawn from the trials and observational studies, not a personalized prediction.
- Which drug and dose you reach: tirzepatide averaged more than semaglutide in both trials and real-world data; higher tolerated doses generally produced more loss.
- Type 2 diabetes: consistently blunts average weight loss (compare STEP 1 vs STEP 2, and SURMOUNT-1 vs SURMOUNT-2).
- Adherence and how long you stay on: averages are measured at 68-72 weeks after a slow dose build-up; stopping early or missing doses lowers results.
- Prior weight-loss medication use: in the 2026 Mayo Clinic Proceedings study, people who had used obesity drugs before lost less (semaglutide 10.4% vs 14.4%).
- Side-effect tolerance: nausea and other GI effects can limit the dose some people can reach.
- Lifestyle context: all pivotal trials paired the drug with diet and physical-activity counseling; the numbers reflect medication plus lifestyle, not medication alone.
- Individual biology and genetics: research suggests real differences in response, but no clinically available test predicts your outcome yet.
A word on supplements and "natural Ozempic"
Products marketed as "natural Ozempic" — berberine, apple-cider-vinegar blends, and similar supplements — are not FDA-approved to treat obesity and are not equivalent to prescription GLP-1 medications. The FDA does not evaluate dietary supplements for weight-loss efficacy the way it reviews prescription drugs, and no supplement has trial evidence anywhere near the 15-22% average losses documented for semaglutide and tirzepatide. Treat the before-and-after marketing for these products with particular skepticism. If weight management is a goal, a licensed clinician can walk you through evidence-based options.