Mounjaro Weight Loss Calculator
Estimate your potential weight loss on Mounjaro (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 Mounjaro Weight Loss Calculator?
Contents
Mounjaro Dosing Schedule and Weight Loss by Dose
Dose Escalation Schedule
| Weeks | Dose | Purpose |
|---|---|---|
| 1–4 | 2.5 mg | Initiation (not therapeutic for weight loss) |
| 5–8 | 5.0 mg | First maintenance dose |
| 9–12 | 7.5 mg | Intermediate step (optional) |
| 13–16 | 10.0 mg | Standard maintenance dose |
| 17–20 | 12.5 mg | Intermediate step (optional) |
| 21+ | 15.0 mg | Maximum dose |
SURMOUNT-1 Trial Results: Weight Loss by Dose at 72 Weeks
| Group | Avg. Weight Loss (%) | Avg. Weight Loss (lbs)* | % Losing ≥20% |
|---|---|---|---|
| 5 mg | 15.0% | 34 lbs | 32% |
| 10 mg | 19.5% | 45 lbs | 46% |
| 15 mg | 22.5% | 52 lbs | 57% |
| Placebo | 3.1% | 7 lbs | 1.5% |
*Approximate lbs based on mean baseline weight of 231 lbs (104.8 kg). Mean BMI at baseline was 38.0. All participants received lifestyle counseling.
How Mounjaro (Tirzepatide) Works for Weight Loss
Mechanism of Action
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.
Combined effect: Greater calorie reduction and metabolic improvement than either pathway alone.
In the SURMOUNT-1 trial (N=2,539), participants taking tirzepatide 15 mg lost an average of 22.5% of their body weight over 72 weeks, compared to 3.1% with placebo. This represents one of the largest weight reductions ever achieved with a pharmaceutical intervention in clinical trials.
SURMOUNT Trial Results by Dose
5 mg: 15.0% average body weight loss at 72 weeks (SURMOUNT-1)
10 mg: 19.5% average body weight loss at 72 weeks (SURMOUNT-1)
15 mg: 22.5% average body weight loss at 72 weeks (SURMOUNT-1)
Placebo: 3.1% average body weight loss at 72 weeks
Mounjaro 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; some 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 |
|---|---|---|---|
| Month 3 (~12 weeks) | ~5% | ~7% | ~8% |
| Month 6 (~24 weeks) | ~10% | ~14% | ~16% |
| Month 9 (~36 weeks) | ~13% | ~17% | ~20% |
| Month 12 (~52 weeks) | ~14% | ~19% | ~21% |
| Month 18 (~72 weeks) | ~15% | ~19.5% | ~22.5% |
Source: SURMOUNT-1 trial (Jastreboff et al., NEJM 2022). Values are approximate averages.
Mounjaro vs Ozempic Comparison
| Feature | Mounjaro (tirzepatide) | Ozempic (semaglutide) |
|---|---|---|
| Mechanism | Dual GIP/GLP-1 agonist | GLP-1 agonist only |
| Max Weight Loss | ~22.5% (SURMOUNT-1) | ~14.9% (STEP 1, Wegovy dose) |
| Dose Range | 2.5 mg - 15 mg weekly | 0.25 mg - 2.4 mg weekly |
| FDA Approved For | Type 2 diabetes; weight management (as Zepbound) | Type 2 diabetes; weight management (as Wegovy) |
| Trial Duration | 72 weeks (SURMOUNT-1) | 68 weeks (STEP 1) |
For personalized Ozempic projections, try 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 of Mounjaro
| Coverage | Estimated Monthly Cost |
|---|---|
| Without insurance (cash price) | $1,000 - $1,200 |
| Commercial insurance (with coverage) | $25 - $150 |
| Manufacturer savings card (eligible patients) | As low as $25 |
| Medicare/Medicaid | Varies; limited coverage for weight loss indication |
Costs vary by pharmacy, insurance plan, and region. The manufacturer (Eli Lilly) offers a savings program for eligible commercially insured patients. Check with your insurance provider for specific coverage details.
Frequently Asked Questions
How much weight can I lose on Mounjaro?
In the SURMOUNT-1 trial (N=2,539), participants taking the highest dose of 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. Some participants lost more than 25% of their body weight.
How does Mounjaro compare to Ozempic for weight loss?
Mounjaro (tirzepatide) targets both GIP and GLP-1 receptors, while Ozempic (semaglutide) targets only GLP-1. In clinical trials, tirzepatide at maximum dose produced 22.5% average weight loss versus semaglutide's 14.9% at its highest weight-loss dose (Wegovy 2.4 mg). However, individual results vary, and the SURPASS-2 trial (tirzepatide vs semaglutide 1 mg for diabetes) showed tirzepatide produced greater weight loss at all doses. Use our Ozempic calculator for semaglutide projections.
What is the Mounjaro dosing schedule?
Mounjaro starts at 2.5 mg weekly for 4 weeks (titration only, not a therapeutic dose). After 4 weeks, the dose increases to 5 mg. Your provider may then increase the dose by 2.5 mg every 4 weeks (to 7.5 mg, 10 mg, 12.5 mg, or 15 mg) based on your response and tolerability. Not all patients need or tolerate the maximum 15 mg dose. The dose escalation is gradual to minimize gastrointestinal side effects.
When will I start losing weight on Mounjaro?
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.
What are the common side effects of Mounjaro?
The most common side effects are gastrointestinal: nausea (24-33%), diarrhea (17-23%), decreased appetite (15-20%), vomiting (8-13%), constipation (6-11%), and abdominal pain (5-8%). These are typically mild to moderate and most common during dose escalation. Serious but rare side effects include pancreatitis, gallbladder problems, and hypoglycemia (especially when used with insulin or sulfonylureas).
Will I regain weight after stopping Mounjaro?
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 lost additional weight. Maintaining dietary changes and exercise habits after stopping the medication can reduce the extent of regain, but some rebound is expected.
Is this calculator based on real clinical trials?
Yes. The weight loss projections are derived from the SURMOUNT clinical trial program. SURMOUNT-1 was published in the New England Journal of Medicine (Jastreboff et al., 2022, N=2,539) and studied tirzepatide in adults with obesity or overweight without diabetes. SURMOUNT-2 studied tirzepatide in adults with obesity and type 2 diabetes. These trials represent the strongest available evidence for tirzepatide weight loss outcomes.
Can I take Mounjaro if I don't have diabetes?
Mounjaro is FDA-approved for type 2 diabetes. However, the same drug (tirzepatide) is marketed as Zepbound for chronic weight management in adults with obesity (BMI 30+) or overweight (BMI 27+) with at least one weight-related condition. Your healthcare provider can determine which indication and brand is appropriate for your situation.
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.
- 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. Mounjaro (tirzepatide) Prescribing Information. FDA.gov.
- Eli Lilly. Zepbound (tirzepatide) Prescribing Information. FDA.gov.
This calculator uses peer-reviewed formulas and clinical guidelines. Results are estimates and should not replace professional medical advice.