How effective will MariTide be for weight loss?
The investigational weight loss drug MariTide (maridebart cafraglutide) achieved 12%–16% mean weight loss (intent-to-treat) in obese patients without diabetes, and up to 20% when excluding dropouts after 52 weeks in phase 2 trials, compared to about 2% with placebo. Notably, weight loss was still ongoing at one year, indicating further potential.
MariTide Phase 2 Clinical Trial Results
Phase 2 studies of MariTide included two groups: adults with obesity, and adults with obesity and type 2 diabetes. The primary end point of the studies was the percent change in body weight from baseline over 52 weeks.
In adults with obesity but no diabetes:
- Mean weight loss: –12.3% to –16.2% (intent-to-treat); –16.3% to –19.9% (efficacy estimand) at 52 weeks.
- Placebo group: –2.5% to -2.6% weight loss.
In adults with obesity and type 2 diabetes:
- Mean weight loss: –8.4% to –12.3% (intent-to-treat); –12.1% to –17.0% (efficacy estimand).
- Placebo group: -1.4% to –1.7% weight loss.
Weight loss curves had not plateaued by Week 52, suggesting further loss is possible with continued treatment.
Who Lost How Much?
Proportion of MariTide users achieving weight loss milestones (obesity cohort, highest dose):
- ≥ 5% loss: 85% (vs 26% with placebo)
- ≥ 10% loss: 72% (vs 12% with placebo)
- ≥ 15% loss: 54% (vs 3% with placebo)
Proportion of MariTide users achieving weight loss milestones (obesity and type 2 diabetes cohort, highest dose):
- ≥ 5% loss: 78% (vs. 16% with placebo)
- ≥ 10% loss: 63% (vs 1% with placebo)
- ≥ 15% loss: 47% (vs 0% with placebo)
Durability and Trajectory
Weight loss was steady and progressive throughout the 52 weeks of the phase 2 studies, with no plateau reached. Extension studies are needed to test whether monthly or less frequent dosing can maintain or enhance this effect over longer periods. Dose escalation strategies (starting at a lower dose and gradually increasing) have improved tolerability and reduced dropouts due to gastrointestinal (GI) side effects without sacrificing efficacy.
Diabetes vs Non-Diabetes Results
Absolute weight loss was smaller in participants with type 2 diabetes, but they still achieved substantial reductions. In those with type 2 diabetes, HbA1c (blood sugar marker) fell by 1.2%–1.6%, and most met American Diabetes Association (ADA) weight targets. Cardiometabolic improvements (blood pressure, cholesterol, inflammation) were also observed.
How Does MariTide Compare to Today’s Leaders?
Based on phase 2 trials, MariTide’s efficacy is between Wegovy and Zepbound for adults identified as obese, but with only monthly injections, potentially improving convenience and adherence.
| Drug & Dose | Mean % Loss | Duration | Frequency | Study |
| MariTide 420 mg | 16–20% | 52 weeks | Monthly | NEJM 2025 |
| Semaglutide (Wegovy) 2.4 mg | 15% | 68 weeks | Weekly | STEP 1 |
| Tirzepatide (Zepbound) 15 mg | 21% | 72 weeks | Weekly | SURMOUNT 1 |
Related questions
- Is obesity a major risk factor for Covid-19?
- Mounjaro vs Ozempic: Which is right for you?
- Zepbound vs Mounjaro: Comparison Guide for Weight Loss and Diabetes Treatment
What Phase 3 Trials Will Confirm
Phase 3 trials are the critical next step in determining whether MariTide’s promising phase 2 results will hold up in a much larger and more diverse population. These studies are designed to rigorously evaluate the drug’s long-term safety, efficacy, and tolerability over 72 weeks, using optimized dosing strategies and enrolling thousands of participants with obesity, both with and without type 2 diabetes. The outcomes will provide the definitive evidence needed for regulatory approval and to guide future clinical use.
- Ongoing phase 3 MARITIME trials (72 weeks) will test optimized dose escalation (21→35→70 mg), aiming to maintain weight loss with fewer GI side effects.
- Primary endpoint: Percent weight change at Week 72
- Key secondary endpoints: Include change in waist circumference, proportion achieving ≥5%, ≥10%, and ≥15% weight loss, change in systolic blood pressure, change in triglycerides, change in HbA1c
Factors That Influence Individual Response
Individual responses to MariTide can vary widely, with some people experiencing dramatic weight loss while others see more modest results. Several factors influence how much weight a person is likely to lose, how well they tolerate the medication, and whether they can maintain their progress over time.
- Baseline BMI: Higher BMI may predict greater absolute weight loss.
- Dose-escalation schedule: Slower escalation reduces GI side effects (nausea, vomiting), which are the main reason for discontinuation.
- Lifestyle add-ons: Diet and activity programs, identical to those used in other GLP-1 trials, improve the odds of achieving ≥15% weight loss.
- Adherence: Those who complete the full treatment period see the greatest benefit.
References
- American Diabetes Association Professional Practice Committee. (2023, December 11). 8. Obesity and Weight Management for the Prevention and Treatment of Type 2 Diabetes: Standards of Care in Diabetes–2024. Diabetes Care, 47(Supplement 1), S145. https://diabetesjournals.org/care/article/47/Supplement_1/S145/153942/8-Obesity-and-Weight-Management-for-the-Prevention
- Amgen. (2024, November 26). AMGEN ANNOUNCES ROBUST WEIGHT LOSS WITH MARITIDE IN PEOPLE LIVING WITH OBESITY OR OVERWEIGHT AT 52 WEEKS IN A PHASE 2 STUDY. Amgen. https://www.amgen.com/newsroom/press-releases/2024/11/amgen-announces-robust-weight-loss-with-maritide-in-people-living-with-obesity-or-overweight-at-52-weeks-in-a-phase-2-study
- Jastreboff, A. M., Ryan, D. H., Bays, H. E., Ebeling, P. R., Mackowski, M. G., Philipose, N., Ross, L., Liu, Y., Burns, C. E., Abbasi, S. A., Pannacciulli, N., & MariTide Phase 2 Obesity Trial Investigators (2025). Once-Monthly Maridebart Cafraglutide for the Treatment of Obesity - A Phase 2 Trial. The New England journal of medicine, 10.1056/NEJMoa2504214. Advance online publication. https://doi.org/10.1056/NEJMoa2504214
- Jastreboff, A. M., Aronne, L. J., Ahmad, N. N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M. C., Stefanski, A., & SURMOUNT-1 Investigators (2022). Tirzepatide Once Weekly for the Treatment of Obesity. The New England journal of medicine, 387(3), 205–216. https://doi.org/10.1056/NEJMoa2206038
- Javor, E., Lucijanić, M., & Skelin, M. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England journal of medicine, 385(1), e4. https://doi.org/10.1056/NEJMc2106918
- MariTime. About the MARITIME-1 study. Accessed on June 29, 2025 at https://www.maritimestudy.com/en-us/maritime-1
Read next
Ozempic Side Effects to Watch For
The most common Ozempic side effects with Ozempic include stomach problems, like nausea, vomiting, diarrhea, stomach pain and constipation. These tend to be mild-to-moderate and usually clear up in a few weeks in most people. Low blood sugar (hypoglycemia) is also a common side effect (when used with certain other diabetes treatments) and it can be serious. Continue reading
Why am I not losing weight on Mounjaro?
It takes time, about 8 to 12 weeks to see a 6% to 8% weight loss in adults using Mounjaro. Other reasons include the need to follow a reduced calorie diet and exercise program, your dose may need to be increased, or side effects may affect your treatment. Continue reading
Ozempic Mounjaro Wegovy & Zepbound: Weight Loss Compared
Ozempic, Mounjaro, Wegovy and Zepbound can all lead to long-term weight loss, but only Wegovy and Zepbound are approved by the FDA for this use. In studies, Zepbound has led to a 21% weight loss in adults using the highest dose, while Wegovy has led to about a 15% weight loss.
Continue readingSee also:
Related medical questions
- Wegovy vs Ozempic: Which is Right for You?
- How long does it take for Ozempic to work?
- Which GLP-1 drug is best for weight loss?
- How long until I'll lose weight with Wegovy?
- Does levothyroxine cause weight gain or loss?
- Do Ozempic, Wegovy, Mounjaro & Zepbound cause hair loss?
- How does Ozempic work for weight loss?
- Tirzepatide vs semaglutide: How do they compare?
- Does Wellbutrin XL/SR cause weight gain or loss?
- Why does Lexapro cause weight gain? Complete Patient Guide
- Does Ozempic need to be refrigerated?
- How much is Zepbound with or without insurance?
- Does Lyrica (pregabalin) cause weight gain?
- What happens when you stop taking Ozempic?
- Does Zoloft (sertraline) cause weight gain?
- Does gabapentin cause weight gain?
- Will my insurance cover the cost of Ozempic?
- How long does it take for Zepbound to work?
- How does retatrutide compare to tirzepatide?
- How does Mounjaro Work for Weight Loss?
- Does Prozac cause weight gain or loss?
- Saxenda vs Ozempic: For Weight Loss?
- How effective is Topamax (topiramate) for weight loss?
- Can you get tirzepatide from a compounding pharmacy?
Related support groups
- MariTide (3 questions, 3 members)
- Weight Loss (Obesity/Overweight) (878 questions, 1,516 members)
- Diabetes, Type 2 (515 questions, 1,431 members)