How Much Weight Will I Lose on a GLP-1?
Medically reviewed by Dr. Jaydeep Sanghani, MBBSLast reviewed August 2026
Enter your weight and dose to project your expected total loss on semaglutide (Wegovy) or tirzepatide (Zepbound) — using the actual average results from the pivotal clinical trials, not marketing numbers.
Want to know when you'll lose it instead? See the month-by-month GLP-1 Weight Loss Timeline.
1. Medication
2. Weekly maintenance dose
3. Your current weight
Already started? Check if you're on schedule
See how your real loss compares to the SURMOUNT-1 (NEJM 2022) average pace at your current week.
Enter your starting weight, weight now, and how many weeks you've been on it to see if you're ahead of or behind the trial-average pace.
The trial-average pace is an approximate trajectory scaled to the SURMOUNT-1 (NEJM 2022) endpoint, a directional guide, not a precise clinical curve. Individual results vary widely.
Educational estimate only, based on published trial averages, not a prediction of your personal result, and not medical advice. Weight loss depends on your dose, how long you stay on it, side-effect tolerance, diet, and activity. Discuss any medication with a licensed clinician.
How this projection works
This tool doesn't guess. It applies the average total body-weight reduction measured in each medication's pivotal randomized trial to your starting weight.
For semaglutide, that's the STEP 1 trial: adults with overweight or obesity (without diabetes) lost an average of 14.9% of body weight on the 2.4 mg dose over 68 weeks, versus 2.4% on placebo.
For tirzepatide, that's SURMOUNT-1: average losses of 15% (5 mg), 19.5% (10 mg), and 20.9% (15 mg) over 72 weeks, versus about 3% on placebo — the largest average reductions seen with any approved anti-obesity medication to date.
Because people at the same dose had very different outcomes, the calculator also shows a realistic range rather than a single number. Real-world results are often a little below trial results, since trials support adherence closely.
A number on the scale isn't the whole story. Up to 40% of weight lost on a GLP-1 can be muscle if you don't protect it. Pair any projection with enough protein and resistance training, and track fat vs. muscle — not just weight.
Turn your projection into a plan
Save this projection to your dashboard and let Calqulate track you against it week by week — with plateau alerts when the curve flattens.
- Weekly weigh-ins and progress charts
- Injection-day reminders and dose history
- Body-composition trend (fat vs lean mass)
- Doctor-ready PDF export
Your entries are private. Export or delete any time.
Frequently Asked Questions
Common questions and answers about this calculator.
How much weight will I lose on a GLP-1?
In the pivotal trials, adults without diabetes lost an average of about 14.9% of body weight on semaglutide 2.4 mg (STEP 1, 68 weeks) and about 15%, 19.5%, and 20.9% on tirzepatide 5 mg, 10 mg, and 15 mg (SURMOUNT-1, 72 weeks). These are averages over more than a year at the top dose — your result depends on your dose, adherence, protein intake, and activity.
Is this calculator a guarantee of my results?
No. It applies published trial averages to your starting weight to give a realistic target and range. Real-world results are usually a little lower than trial results because trials support adherence closely, and individual response varies widely.
Why does the calculator show a range instead of one number?
Because trial participants at the same dose had very different outcomes — some lost far more than average, some less. The 'modest' and 'strong responder' band reflects that real spread so you're not anchored to a single optimistic number.
Which loses more weight, tirzepatide or semaglutide?
On average, tirzepatide (Zepbound/Mounjaro) produces more weight loss than semaglutide (Wegovy/Ozempic) at the top doses. But the best medication is the one you can access, afford, tolerate, and stay on. See our tirzepatide vs semaglutide comparison for the full picture.
Sources
- Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)Wilding JPH, Batterham RL, Calanna S, et al. N Engl J Med. 2021;384(11):989–1002. doi:10.1056/NEJMoa2032183
- Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)Jastreboff AM, Aronne LJ, Ahmad NN, et al. N Engl J Med. 2022;387(3):205–216. doi:10.1056/NEJMoa2206038
- Wegovy (semaglutide) Prescribing InformationU.S. Food & Drug Administration (FDA). 2023.
- Zepbound (tirzepatide) Prescribing InformationU.S. Food & Drug Administration (FDA). 2023.
Tool Information
August 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.
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