Search “best peptides for weight loss” and you’ll find lists that put prescription drugs with 70-week trials next to compounds that have only been tested in mice. That’s not a fair fight. This guide ranks weight-loss peptides by the strength of their human evidence first, then by results, and tells you plainly which ones you can legally get and which ones are still experimental.
Key takeaways
- The peptides with real, large human trials are all in the incretin family: tirzepatide, semaglutide, liraglutide, and the pipeline drugs retatrutide, CagriSema and survodutide.
- Among FDA-approved options, tirzepatide (Zepbound) delivers the most average weight loss, about 20 to 22% in its main trial. High-dose semaglutide (Wegovy HD, 7.2 mg) now comes close at about 21%.
- Retatrutide has the strongest numbers of all (about 28% in phase 3) but is not approved.
- Popular “research” peptides such as AOD-9604 and MOTS-c lack convincing human weight-loss data. AOD-9604 actually failed its larger trial.
How we ranked them
Each compound was placed in one of three evidence tiers:
- Tier 1, FDA-approved for weight: backed by large randomized phase 3 trials and a full safety label.
- Tier 2, late-stage pipeline: strong phase 3 data, but not yet approved in the US.
- Tier 3, weak or no human evidence: animal data, small pilot studies, or failed trials.
Weight-loss figures are average percent of body weight lost in each drug’s main obesity trial. Trials differ in length and population, so treat side-by-side numbers as approximate.
Quick comparison table
| Compound | How it works | US status (Oct 2026) | Main trial result |
|---|---|---|---|
| Retatrutide | GIP + GLP-1 + glucagon | Investigational | 28.3% at 80 weeks (TRIUMPH-1) |
| Tirzepatide (Zepbound) | GIP + GLP-1 | Approved | about 20 to 22.5% at 72 weeks (SURMOUNT-1) |
| CagriSema | Amylin + GLP-1 | Under FDA review | about 20 to 23% at 68 weeks (REDEFINE 1) |
| Semaglutide 7.2 mg (Wegovy HD) | GLP-1 | Approved 2026 | 20.7% at 72 weeks (STEP UP) |
| Survodutide | GLP-1 + glucagon | Investigational | up to 16.6% at 76 weeks (SYNCHRONIZE-1) |
| Semaglutide 2.4 mg (Wegovy) | GLP-1 | Approved | 14.9% at 68 weeks (STEP 1) |
| Oral semaglutide 25 mg (Wegovy pill) | GLP-1 | Approved | roughly 14 to 17% at 64 weeks (OASIS 4) |
| Liraglutide (Saxenda) | GLP-1, daily | Approved | about 8% at 56 weeks (SCALE) |
| AOD-9604 | Growth hormone fragment | Not approved | No significant loss vs placebo |
| MOTS-c | Mitochondrial peptide | Not approved | Animal data only |
Tier 1: FDA-approved weight-loss peptides
1. Tirzepatide (Zepbound)
Tirzepatide is a once-weekly injection that activates both GIP and GLP-1 receptors. In SURMOUNT-1, people on the 15 mg dose lost about a fifth of their body weight. In the SURMOUNT-5 head-to-head trial it beat semaglutide 2.4 mg (about 20% versus about 14% at 72 weeks). It is also approved for obstructive sleep apnea in adults with obesity. Per the label, it starts at 2.5 mg weekly and steps up by 2.5 mg no faster than every 4 weeks, to a maintenance dose of 5, 10 or 15 mg.
2. Semaglutide (Wegovy, Wegovy HD and the Wegovy pill)
Semaglutide is the most studied drug on this list, with years of data including the SELECT trial, which showed a 20% reduction in major heart events in people with heart disease and overweight. It now comes in three weight-management forms:
- Wegovy injection, up to 2.4 mg weekly (about 15% average loss).
- Wegovy HD, a 7.2 mg weekly dose approved in 2026 for people who have tolerated 2.4 mg for at least 4 weeks (about 21% in STEP UP).
- Wegovy pill, a 25 mg daily oral tablet approved in late 2025.
See our semaglutide titration schedule for how the doses step up.
3. Liraglutide (Saxenda)
Liraglutide was the first GLP-1 approved for weight management. It is injected daily and produces smaller results, around 8% on average. Its advantages are a long safety record and growing generic availability, which can lower cost.
A note on Foundayo (orforglipron): Lilly’s once-daily weight-loss pill was approved in April 2026 and produced about 11% average loss at its top dose. It works on the GLP-1 receptor, but it’s a small molecule, not a peptide, so it doesn’t strictly belong on a peptide list.
Tier 2: late-stage pipeline peptides
Retatrutide
A triple agonist that adds glucagon activity to GIP and GLP-1. TRIUMPH-1 reported 28.3% average loss at 80 weeks on 12 mg, and 45% of that group lost at least 30% of their weight. Lilly plans to file in early 2027. Full breakdown: retatrutide vs tirzepatide.
CagriSema
A weekly combination of cagrilintide (a long-acting amylin analog) and semaglutide. REDEFINE 1 reported roughly 20 to 23% weight loss at 68 weeks depending on the analysis. Novo Nordisk filed with the FDA in December 2025. More in our amylin drugs explainer.
Survodutide
A GLP-1 and glucagon dual agonist from Boehringer Ingelheim and Zealand Pharma. SYNCHRONIZE-1 reported up to 16.6% average loss at 76 weeks. It is also being studied for fatty liver disease (MASH).
Tier 3: popular peptides with weak evidence
- AOD-9604: a fragment of growth hormone marketed for fat loss. In a randomized trial of more than 500 people it did not produce meaningful weight loss compared with placebo, and development for obesity was dropped.
- MOTS-c: a peptide encoded by mitochondrial DNA that improved metabolism and prevented weight gain in mice. There are no published human weight-loss trials.
- Growth hormone secretagogues (CJC-1295, ipamorelin, sermorelin): raise growth hormone, which can shift body composition, but none has shown meaningful weight loss in trials. Tesamorelin is FDA-approved only to reduce excess belly fat in people with HIV-related lipodystrophy. See our secretagogues guide.
- 5-amino-1MQ and SLU-PP-332: often sold alongside peptides, but they are small molecules, not peptides, and have no human weight-loss data.
Safety basics for the whole incretin class
- Most common: nausea, diarrhea, constipation and vomiting, mainly during dose increases.
- Less common but serious: pancreatitis, gallbladder disease, kidney injury from dehydration, and low blood sugar when combined with insulin or sulfonylureas.
- Rapid loss can include muscle loss. Adequate protein and resistance training help protect lean mass.
- Weight tends to return after stopping, so these are generally long-term treatments.
Unapproved versions sold online as “research peptides” carry extra risks: wrong dose, contamination and no sterility guarantee. Learn how to read a COA and why research use only products are not meant for people.
Frequently asked questions
What is the most effective peptide for weight loss?
Among approved options, tirzepatide (Zepbound) has the largest average weight loss, about 20 to 22.5% in its main trial. The investigational drug retatrutide has shown about 28% in phase 3 but is not approved.
Is semaglutide or tirzepatide better for weight loss?
In the head-to-head SURMOUNT-5 trial, tirzepatide produced more weight loss than semaglutide 2.4 mg (about 20% versus 14%). The newer 7.2 mg semaglutide dose narrows that gap.
Does AOD-9604 work for weight loss?
Its larger randomized trial did not show meaningful weight loss compared with placebo.
Are weight-loss peptides safe?
Approved incretin drugs have well-documented side effects, mostly digestive, plus rarer risks such as pancreatitis and gallbladder disease. They should be used under medical supervision. Unapproved research peptides have unknown quality and safety.
Do you regain weight after stopping weight-loss peptides?
Trials show most people regain a large share of lost weight within a year of stopping, which is why these drugs are usually long-term treatments.
Sources
- Jastreboff AM et al., SURMOUNT-1, N Engl J Med, 2022
- Aronne LJ et al., SURMOUNT-5 tirzepatide vs semaglutide, N Engl J Med, 2025
- Wilding JPH et al., STEP 1, N Engl J Med, 2021
- Lincoff AM et al., SELECT, N Engl J Med, 2023
- Eli Lilly, TRIUMPH-1 topline results, May 2026
- Healio, FDA approves high-dose Wegovy 7.2 mg, 2026
- PharmaTimes, survodutide SYNCHRONIZE-1 results, April 2026
- Pi-Sunyer X et al., SCALE liraglutide trial, N Engl J Med, 2015
Medical disclaimer: Pep Guide is for educational purposes only. It is not medical advice, diagnosis or treatment. Research changes over time. Talk to a licensed healthcare provider before starting, stopping or changing any medication or compound.