Best Peptides for Weight Loss
Most "best peptide" lists rank by popularity. This one ranks by evidence: how much weight was lost, in how many people, over how long, in a published trial. That filter removes about half the compounds usually recommended for fat loss — and it puts one clear group on top.
One methodological note, because it changes the numbers you see quoted elsewhere. Modern obesity trials report two figures: the treatment-policy estimand, which counts everyone randomized including those who stopped early, and the trial-product estimand, which models full adherence. The second is always the larger number, and it is the one marketing tends to quote. Every figure below is the treatment-policy result, so the comparisons are like-for-like.
The ranking at a glance
| # | Compound | Mechanism | Best published result | Evidence |
|---|---|---|---|---|
| 1 | Retatrutide | GIP + GLP-1 + glucagon | −30.3% at 104 weeks | Phase 3 reporting |
| 2 | Tirzepatide | GIP + GLP-1 | −20.9% at 72 weeks | Approved, large Phase 3 |
| 3 | CagriSema (cagrilintide + semaglutide) | Amylin + GLP-1 | −20.4% at 68 weeks | Phase 3 reported |
| 4 | Semaglutide | GLP-1 | −14.9% at 68 weeks | Approved, large Phase 3 |
| 5 | Survodutide | GLP-1 + glucagon | −14.9% at 46 weeks | Phase 2 complete |
| 6 | 5-Amino-1MQ | NNMT inhibition | Preclinical only | Animal data |
| 7 | AOD-9604 | hGH fragment | Not superior to placebo | Human trials, negative |
| 8 | MOTS-c | Mitochondrial peptide | Preclinical metabolic effects | Animal data only |
1. Retatrutide — the strongest data available
Retatrutide hits three receptors: GIP and GLP-1, like tirzepatide, plus glucagon. The glucagon arm increases energy expenditure rather than only suppressing appetite, which appears to be why the numbers are higher than anything before it. Phase 2 reported 24.2% at 48 weeks in the 12 mg arm with the curve still descending; Phase 3 TRIUMPH-1 then reported 28.3% at 80 weeks and 30.3% at 104 weeks, which is the first time any obesity pharmacotherapy has crossed 30% in a trial setting.
The catch is regulatory, not pharmacological: it is not approved, so it exists only as a research compound. Dosing followed a slow four-week titration from 2 mg toward 8–12 mg weekly — see our retatrutide dosage guide for the full schedule.
Verdict: the most effective compound in the class by a clear margin, and the least accessible.
Retatrutide (RTA) — 10 mg — American Peptides
Batch-tested with HPLC and mass spectrometry, COA provided. Research use only.
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2. Tirzepatide — the best evidence-to-availability ratio
Tirzepatide's SURMOUNT-1 trial reported 20.9% weight reduction at 72 weeks at the 15 mg dose, in 2,539 participants. Unlike retatrutide it is an approved medicine, which means a prescription pathway exists and the safety database is genuinely large.
Verdict: if you want the strongest result that is actually approved, this is it.
3. CagriSema — amylin plus GLP-1
Cagrilintide is a long-acting amylin analogue; paired with semaglutide it produced 20.4% reduction at 68 weeks in the REDEFINE 1 Phase 3 trial. You will often see 22.7% quoted instead — that is the trial-product estimand assuming full adherence, not the primary result. The interesting part is the mechanism: amylin signals satiety through a pathway independent of GLP-1, so the two components add rather than overlap.
Verdict: the most promising combination approach; cagrilintide alone has thinner standalone data.
4. Semaglutide — the most studied
14.9% at 68 weeks in STEP-1, plus cardiovascular outcome data from SELECT that no other compound in this list has. Less weight loss than the newer agents, but the deepest evidence base and the longest real-world track record.
Verdict: the conservative choice, and the one with proven outcomes beyond the scale.
5. Survodutide — one to watch
A GLP-1 and glucagon dual agonist that reported 14.9% at 46 weeks in its Phase 2 dose-finding trial, with additional interest in liver outcomes. The 18.7% figure quoted in most coverage is the completers-only result at 4.8 mg rather than the planned-treatment figure — a four-point difference worth knowing about. Fewer trials than the leaders, but the trajectory resembles where retatrutide was two years ago.
6–8. The weaker options, and why they rank low
5-Amino-1MQ inhibits NNMT and reduced fat mass in obese mice. It is widely sold and heavily marketed, but human trial data does not exist yet — the enthusiasm is running well ahead of the evidence.
AOD-9604 is the clearest cautionary tale here. It reached human trials, the obesity program was discontinued in 2007, and no peer-reviewed paper reporting a benefit over placebo was ever published. It is still sold as a fat-loss peptide anyway.
MOTS-c has interesting mitochondrial and insulin-sensitivity effects in animals, and its popularity is rising fast, but human weight-loss data is not there. Worth watching, not worth ranking above the GLP-1 class.
Side effects across the class
The GLP-1 family shares a predictable profile: nausea, vomiting, diarrhea and constipation, concentrated around dose increases and usually easing at a stable dose. Slow titration is the main mitigation. Serious events are rarer — pancreatitis and gallbladder disease appear in trial safety data — and the compounds carry a contraindication for personal or family history of medullary thyroid carcinoma. Loss of lean mass alongside fat is a real consideration across all of them, which is why resistance training and protein intake come up in every serious discussion of these drugs.
Frequently asked questions
Which peptide produces the most weight loss in trials?
Retatrutide, by a clear margin. Its Phase 3 TRIUMPH-1 trial reported 28.3% mean body-weight reduction at 80 weeks and 30.3% at 104 weeks, after 24.2% at 48 weeks in Phase 2. Tirzepatide follows at 20.9% over 72 weeks, CagriSema at 20.4% over 68 weeks, and semaglutide at 14.9% over 68 weeks.
Are there non-prescription peptides for weight loss?
None are approved for weight loss without a prescription. Compounds like retatrutide, cagrilintide and 5-amino-1MQ are available only as research chemicals, which is a legal category for laboratory work rather than an over-the-counter alternative.
Do fat-loss peptides like AOD-9604 work?
AOD-9604, a fragment of human growth hormone, showed promise in mouse studies. It went into human trials, the obesity program was discontinued in 2007, and no peer-reviewed result showing benefit over placebo was ever published. The evidence behind it is not merely weaker than the GLP-1 class — for humans it is absent.
What happens when you stop taking a GLP-1 peptide?
Trial follow-up consistently shows substantial weight regain after discontinuation. In the semaglutide withdrawal extension, participants regained about two-thirds of what they had lost within a year of stopping.
The full GLP-1 research line — American Peptides
Retatrutide, tirzepatide, semaglutide, cagrilintide and blends — all with batch certificates of analysis. Coupon below for 10% off.
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Sources
- Jastreboff AM et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine, 2023;389(6):514–526. PubMed
- Eli Lilly. TRIUMPH-1 Phase 3 topline results, May 2026 (NCT05929066) and TRIUMPH-3 topline, July 2026 (NCT05882045). Trial design: Giblin K et al. Diabetes, Obesity and Metabolism, 2026;28(1):83–93. PubMed
- Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine, 2022;387(3):205–216. PubMed
- Garvey WT et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity (REDEFINE 1). New England Journal of Medicine, 2025;393(7):635–647. PubMed
- Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP-1). New England Journal of Medicine, 2021;384(11):989–1002. PubMed
- le Roux CW et al. Glucagon and GLP-1 receptor dual agonist survodutide for obesity: a randomised, double-blind, placebo-controlled, dose-finding phase 2 trial. The Lancet Diabetes & Endocrinology, 2024;12(3):162–173. PubMed
- Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism, 2022;24(8):1553–1564. PubMed
Related guides
- Best peptides for fat loss — the same compounds judged on body composition rather than total weight
- Retatrutide: complete guide
- Retatrutide dosage and titration chart
- Where to buy retatrutide: supplier vetting
- Peptide reconstitution calculator
- Are peptides safe?