Best Peptide for Weight Loss
Semaglutide, Tirzepatide, Retatrutide & More — Ranked by Fat Loss Efficacy (2026)
Weight loss peptides split into two categories: GLP-1/GIP receptor agonists (semaglutide, tirzepatide, retatrutide) with FDA-reviewed clinical trial data showing 15–29% body weight reduction, and research peptides targeting fat metabolism (AOD-9604, ipamorelin, 5-Amino-1MQ). GLP-1 medications are the most effective weight loss peptides ever studied in humans. Research peptides offer complementary mechanisms — but without equivalent clinical evidence. Track any of them in Shotlee.
Top Weight Loss Peptides — Ranked by Efficacy
| Peptide | Type | Best Clinical Result | FDA Status | Evidence Level |
|---|---|---|---|---|
| Retatrutide | GIP + GLP-1 + Glucagon | 28.7% mean loss (68 wks, Phase 3) | Investigational | ⭐⭐⭐⭐⭐ |
| Tirzepatide | GIP + GLP-1 dual agonist | 20.9% mean loss (72 wks) | Approved (Mounjaro/Zepbound) | ⭐⭐⭐⭐⭐ |
| Semaglutide | GLP-1 agonist | 14.9% mean loss (68 wks) | Approved (Ozempic/Wegovy) | ⭐⭐⭐⭐⭐ |
| Cagrisema | Amylin + GLP-1 combo | ~15.6% (Phase 2) | Phase 3 | ⭐⭐⭐⭐ |
| AOD-9604 | hGH fragment (176-191) | Modest fat reduction (Phase 2) | Not approved | ⭐⭐ |
| Ipamorelin | GHRP (GH secretagogue) | GH pulse increase, indirect fat loss | Research only | ⭐⭐ |
| 5-Amino-1MQ | NNMT inhibitor | Preclinical fat loss data | Research only | ⭐ |
| Tesamorelin | GHRH analogue | Visceral fat reduction in HIV lipodystrophy | Approved (Egrifta, limited) | ⭐⭐⭐ |
Evidence level reflects depth of human clinical trial data. "Research only" compounds lack Phase 3 human efficacy data. [1, 2, 3]
#1 Category: GLP-1 / Dual / Triple Agonists (FDA-Reviewed)
Retatrutide (Triple Agonist)
Tirzepatide (Mounjaro/Zepbound)
#2 Category: Research Peptides Targeting Fat Metabolism
AOD-9604 (hGH Fragment 176-191)
Ipamorelin (GHRP)
Tesamorelin (GHRH Analogue)
5-Amino-1MQ (NNMT Inhibitor)
How to Choose the Right Weight Loss Peptide
If your goal is meaningful, medically supervised weight loss with the strongest evidence base, the answer is clear: start with an approved GLP-1 receptor agonist. Tirzepatide gives you the best currently-approved weight loss result. Semaglutide has the strongest cardiovascular outcome data. Both are covered by insurance for eligible patients.
If you are a biohacker interested in body composition optimisation on top of a GLP-1 protocol, complementary research peptides like tesamorelin (visceral fat) or ipamorelin (GH-axis support) may have theoretical additive benefits — but the evidence base is significantly weaker and these are research-use only in most jurisdictions.
Retatrutide represents the next generation — early Phase 3 data shows 28.7% mean weight loss, the highest ever reported in a Phase 3 trial. It is not yet available, but tracking your current protocol in Shotlee builds the baseline data you will need to compare outcomes when it launches.
Track Any Protocol in Shotlee
Whether you are on semaglutide, tirzepatide, or a research peptide stack, Shotlee tracks your dose logs, weekly weight, side effects, and lab results in one place — all for free.
How to Track Your Weight Loss Protocol
Set a baseline: log your weight, waist measurement, and any available lab values (HbA1c, fasting glucose, lipids) before starting
Record every injection: date, dose, site, and any immediate reactions — build a complete dose history from day one
Log weekly weight (same day, same time, same conditions) to separate dose-response signal from noise
Track side effects with severity ratings so your prescriber can make informed dose decisions
Add lab results at each clinic visit to measure the biomarker changes your protocol is driving
Frequently Asked Questions
By clinical trial data, retatrutide (Phase 3: 28.7% mean weight loss) is the most effective weight loss compound ever tested, though it is not yet FDA approved. Among approved medications, tirzepatide (20.9% mean weight loss, SURMOUNT-1) outperforms semaglutide (14.9%, STEP-1). Track your progress with whichever compound you use in Shotlee.
No. AOD-9604 showed modest fat reduction in Phase 2 human trials and failed to show joint benefit in Phase 3. Semaglutide in the STEP-1 trial showed 14.9% mean weight loss — a magnitude that AOD-9604 has never demonstrated in human studies. They serve different purposes and are not comparable.
Some biohackers combine GLP-1 medications with GHRPs like ipamorelin for body composition goals. There is no clinical trial data on this combination. GLP-1s act on appetite and metabolism directly; ipamorelin acts on GH pulsatility. If you experiment with stacking, track both compounds carefully in Shotlee and discuss with your prescriber.
GLP-1 agonists (semaglutide, tirzepatide): measurable weight loss starts within 4–8 weeks, with maximum effect over 6–12 months. Research peptides like ipamorelin: GH effects are immediate but fat loss benefits — if any — are gradual and mild over weeks to months. Track weekly weight from day one in Shotlee to see your personal response curve.
In most countries, research peptides (AOD-9604, ipamorelin, BPC-157, etc.) are not FDA-approved for human use and cannot be legally marketed for weight loss. They exist in a regulatory grey area as "research chemicals." Approved medications (semaglutide, tirzepatide) require a prescription and are the only legally sanctioned weight management peptide therapies in the US.
References
- [1]Clinical TrialWilding JPH, et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." NEJM. 2021;384(11):989-1002.
- [2]Clinical TrialJastreboff AM, et al. "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM. 2022;387(3):205-216.
- [3]Press ReleaseEli Lilly. "Lilly's retatrutide met both co-primary endpoints in Phase 3 TRIUMPH-4 trial." Press release, December 11, 2025.
Track Your Weight Loss Protocol in Shotlee
Whatever peptide you use, Shotlee gives you clean dose logs, weekly weight trends, and side effect tracking — free.
🚀 Use Shotlee for Free