Zepbound Weight Loss Calculator
Project your expected weight loss on Zepbound (tirzepatide) based on SURMOUNT clinical trial data.
These are estimates based on average outcomes from the SURMOUNT clinical trials. Individual results vary significantly. Consult your healthcare provider before starting or adjusting any GLP-1/GIP medication.
What Is the Zepbound Weight Loss Calculator?
Contents
What Is Zepbound?
How Zepbound Works
GLP-1 receptor activation: Slows gastric emptying, reduces appetite, and increases satiety signals to the brain.
GIP receptor activation: Enhances insulin secretion, improves fat metabolism, and may increase energy expenditure.
Dual mechanism: By targeting both GIP and GLP-1 receptors simultaneously, Zepbound produces greater appetite suppression and metabolic improvement than GLP-1-only drugs like semaglutide (Wegovy/Ozempic).
Who Is Zepbound For?
Zepbound is FDA-approved for adults with:
- Obesity: BMI of 30 or greater, OR
- Overweight with comorbidities: BMI of 27 or greater with at least one weight-related condition (such as high blood pressure, type 2 diabetes, high cholesterol, or obstructive sleep apnea)
Unlike Mounjaro, Zepbound does not require a type 2 diabetes diagnosis. It is specifically indicated for weight management alongside a reduced-calorie diet and increased physical activity.
SURMOUNT Trial Results
SURMOUNT-1: Weight Loss by Dose at 72 Weeks
5 mg: 15.0% average body weight loss (N=630)
10 mg: 19.5% average body weight loss (N=636)
15 mg: 22.5% average body weight loss (N=630)
Placebo: 3.1% average body weight loss (N=643)
In SURMOUNT-1, 2,539 adults with obesity (BMI 30+) or overweight (BMI 27+) with at least one weight-related condition were randomized to tirzepatide or placebo. More than one-third of participants on the 15 mg dose lost over 25% of their body weight.
Other SURMOUNT Trials
| Trial | Population | Key Finding |
|---|---|---|
| SURMOUNT-1 | Obesity/overweight without diabetes | Up to 22.5% weight loss at 72 weeks |
| SURMOUNT-2 | Obesity/overweight with type 2 diabetes | Up to 14.7% weight loss at 72 weeks |
| SURMOUNT-3 | Obesity after intensive lifestyle intervention | 26.6% total weight loss (lifestyle + drug) |
| SURMOUNT-4 | Weight maintenance after initial loss | Continued treatment maintained weight loss; discontinuation led to ~50% regain |
Zepbound Dosing Schedule
| Weeks | Dose | Purpose |
|---|---|---|
| Weeks 1-4 | 2.5 mg | Initial titration (not a therapeutic dose for weight loss) |
| Weeks 5-8 | 5 mg | First maintenance dose; weight loss begins |
| Weeks 9-12 | 7.5 mg | Optional increase if tolerated and more loss desired |
| Weeks 13-16 | 10 mg | Higher efficacy dose; significant appetite suppression |
| Weeks 17-20 | 12.5 mg | Optional increase for additional weight loss |
| Weeks 21+ | 15 mg | Maximum dose; highest efficacy in SURMOUNT trials |
Not all patients will titrate to 15 mg. Your healthcare provider will determine the optimal dose based on your response, tolerability, and weight loss goals. The 2.5 mg dose is strictly a titration dose and is not intended as a maintenance dose.
Expected Weight Loss Timeline
| Timepoint | 5 mg | 10 mg | 15 mg |
|---|---|---|---|
| 12 weeks | ~5% | ~7% | ~8% |
| 24 weeks | ~10% | ~14% | ~16% |
| 36 weeks | ~13% | ~17% | ~20% |
| 52 weeks | ~14% | ~19% | ~21% |
| 72 weeks | ~15% | ~19.5% | ~22.5% |
Source: SURMOUNT-1 trial (Jastreboff et al., NEJM 2022). Values are approximate averages.
Zepbound vs Mounjaro: Same Drug, Different Indication
| Feature | Zepbound | Mounjaro |
|---|---|---|
| Active Ingredient | Tirzepatide | Tirzepatide |
| Manufacturer | Eli Lilly | Eli Lilly |
| FDA Indication | Chronic weight management (obesity/overweight) | Type 2 diabetes |
| Key Trial | SURMOUNT (weight management) | SURPASS (type 2 diabetes) |
| Dose Range | 2.5 mg - 15 mg weekly | 2.5 mg - 15 mg weekly |
| Mechanism | Dual GIP/GLP-1 agonist | Dual GIP/GLP-1 agonist |
| FDA Approval | November 2023 | May 2022 |
For Mounjaro-specific projections (if prescribed for type 2 diabetes), try our Mounjaro Weight Loss Calculator. For semaglutide comparisons, see our Ozempic Weight Loss Calculator.
Side Effects and Considerations
Common Side Effects (SURMOUNT-1 Data)
| Side Effect | Frequency |
|---|---|
| Nausea | 24-33% |
| Diarrhea | 17-23% |
| Decreased appetite | 15-20% |
| Vomiting | 8-13% |
| Constipation | 6-11% |
| Abdominal pain | 5-8% |
Contraindications
- Personal or family history of medullary thyroid carcinoma (MTC)
- Multiple endocrine neoplasia syndrome type 2 (MEN 2)
- Known hypersensitivity to tirzepatide
- Use with caution in patients with a history of pancreatitis or gallbladder disease
Cost and Insurance Coverage
| Coverage | Estimated Monthly Cost |
|---|---|
| Without insurance (cash price) | $1,000 - $1,200 |
| Commercial insurance (with coverage) | $25 - $150 |
| Eli Lilly savings card (eligible patients) | As low as $25 |
| Zepbound direct-to-patient vials | $399 - $549 (single-dose vials, lower than pen price) |
| Medicare/Medicaid | Varies; limited coverage for weight loss indication |
Because Zepbound is specifically approved for weight management (not diabetes), insurance coverage depends on whether your plan covers anti-obesity medications. Many large employers and commercial plans have added obesity medication coverage in recent years. Check with your insurance provider for specific details.
Frequently Asked Questions
How much weight can I lose on Zepbound?
In the SURMOUNT-1 trial (N=2,539), participants taking the highest dose of Zepbound (tirzepatide 15 mg) lost an average of 22.5% of body weight over 72 weeks, compared to 3.1% with placebo. The 10 mg dose produced about 19.5% loss, and the 5 mg dose about 15%. Results depend on dose, duration, starting weight, diet, and exercise habits. More than one-third of participants on 15 mg lost over 25% of their body weight.
What is the difference between Zepbound and Mounjaro?
Zepbound and Mounjaro are the same drug (tirzepatide) made by the same company (Eli Lilly). The only difference is the FDA-approved indication: Zepbound is approved for chronic weight management in adults with obesity or overweight, while Mounjaro is approved for type 2 diabetes. The dosing, mechanism of action, and side effects are identical. The distinction matters primarily for insurance coverage and prescribing. Use our Mounjaro calculator for diabetes-context projections.
How does Zepbound compare to Wegovy for weight loss?
Zepbound (tirzepatide) targets both GIP and GLP-1 receptors, while Wegovy (semaglutide 2.4 mg) targets only GLP-1. In clinical trials, tirzepatide produced greater weight loss: up to 22.5% in SURMOUNT-1 versus 14.9% in the STEP 1 trial for semaglutide. The SURMOUNT-5 trial directly comparing the two confirmed tirzepatide produced significantly more weight loss. Use our Ozempic Weight Loss Calculator for semaglutide projections.
When will I start losing weight on Zepbound?
Most people notice weight loss within the first 4-8 weeks of treatment. In the SURMOUNT trials, significant weight loss was measurable by week 4, with the most rapid loss occurring between weeks 12 and 36 during active dose escalation. The initial 2.5 mg dose is primarily for tolerability, so meaningful weight loss typically begins at the 5 mg dose and above.
Is Zepbound covered by insurance?
Insurance coverage for Zepbound varies. Many commercial insurance plans have begun covering anti-obesity medications, but coverage depends on your specific plan, your BMI, and whether you have weight-related comorbidities. Eli Lilly offers a savings card program for eligible commercially insured patients that can reduce costs to as low as $25/month. In 2024, Eli Lilly also introduced lower-cost single-dose vials ($399-$549/month) available through LillyDirect for patients who pay out of pocket.
Will I regain weight after stopping Zepbound?
The SURMOUNT-4 trial studied this directly. Participants who switched from tirzepatide to placebo after 36 weeks regained approximately half of the weight they had lost over the following 52 weeks. Those who continued tirzepatide maintained their weight loss and continued losing additional weight. Maintaining dietary changes and exercise habits after stopping the medication can reduce the extent of regain, but some rebound is expected when the medication is discontinued.
Medical Disclaimer: This tool provides general educational estimates. Always consult your prescribing physician or healthcare provider before making medication changes or interpreting results from population-based models.
Sources & Methodology
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. (SURMOUNT-1)
- Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. 2023;402(10402):613-626.
- Wadden TA, Chao AM, Machineni S, et al. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity (SURMOUNT-3). Lancet. 2023;402(10402):600-612.
- Aronne LJ, Sattar N, Horn DB, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity (SURMOUNT-4). JAMA. 2024;331(1):38-48.
- Eli Lilly. Zepbound (tirzepatide) Prescribing Information. FDA.gov.
- FDA approves new medication for chronic weight management. FDA News Release, November 8, 2023.
This calculator uses peer-reviewed formulas and clinical guidelines. Results are estimates and should not replace professional medical advice.