Best peptides for weight loss
Peptides that suppress appetite, increase metabolic rate, or enhance fat oxidation to support significant weight loss.
What to know
GLP-1 receptor agonists (semaglutide, tirzepatide) have the strongest clinical evidence for weight loss. FDA-approved options exist. Expect GI side effects during dose titration. Muscle preservation requires concurrent resistance training and adequate protein intake (1g/lb). Consider metabolic peptides like MOTS-c as adjuncts for those already on GLP-1 therapy.
Recommended peptides
Semaglutide
glp1-weight-loss
Semaglutide is a GLP-1 receptor agonist originally developed for type 2 diabetes that has demonstrated significant weight loss effects in clinical trials. Sold under the brand names Ozempic (diabetes) and Wegovy (weight management), it is the most prescribed anti-obesity medication worldwide as of 2026. Semaglutide works by mimicking the incretin hormone GLP-1, reducing appetite, slowing gastric emptying, and improving insulin sensitivity. The STEP clinical trial program — spanning over 10,000 participants across multiple studies — established semaglutide as a breakthrough treatment for obesity, with average weight loss of 14.9% over 68 weeks. An oral formulation (Rybelsus for diabetes, oral Wegovy for weight loss) expanded access beyond injection-only delivery. Semaglutide also demonstrated cardiovascular benefits in the SELECT trial, reducing major adverse cardiovascular events by 20% in overweight adults.
Tirzepatide
glp1-weight-loss
Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist that has demonstrated greater weight loss than any other approved anti-obesity medication. Sold as Mounjaro (diabetes) and Zepbound (weight management), it activates two complementary incretin pathways simultaneously. The SURMOUNT clinical trial program showed average weight loss of 20.9% at the highest dose — with over half of participants losing 20%+ of body weight. In the landmark SURMOUNT-5 head-to-head trial against semaglutide, tirzepatide produced statistically superior weight loss (20.2% vs 13.7%). Developed by Eli Lilly, tirzepatide represents a paradigm shift from single-receptor to multi-receptor approaches in obesity treatment.
Retatrutide
glp1-weight-loss
Retatrutide (LY3437943) is a first-in-class triple hormone receptor agonist developed by Eli Lilly that simultaneously activates three metabolic pathways: glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon receptors. No other obesity medication in clinical development targets all three receptors in a single molecule. The compound emerged from Eli Lilly's incretin research program, with Phase 1b results published in The Lancet in 2022 (PMID: 36354040) demonstrating approximately 9 kg of body weight reduction in just 12 weeks — enough to advance rapidly into Phase 2. The Phase 2 obesity trial, published in the New England Journal of Medicine in 2023 (PMID: 37366315), produced what was then the highest weight loss ever reported for any pharmaceutical agent: 24.2% body weight reduction over 48 weeks at the 12 mg dose. Every participant in the highest dose group lost at least 5% of their body weight, and 83% lost at least 15%. A parallel Phase 2 trial in patients with type 2 diabetes, published in The Lancet in 2023 (PMID: 37385280), demonstrated dual metabolic benefits: up to 16.9% weight loss alongside a 2.02% reduction in HbA1c at 36 weeks. A dedicated liver fat substudy, published in Nature Medicine in 2024 (PMID: 38858523), showed near-complete resolution of hepatic steatosis — 86% relative reduction in liver fat at the highest dose, with 86% of participants dropping below the 5% threshold that defines normal liver fat content. Retatrutide entered Phase 3 in 2023 through the TRIUMPH clinical trial program — a novel basket trial structure testing the compound simultaneously for obesity, obstructive sleep apnea, and knee osteoarthritis across four major studies enrolling over 5,800 participants (PMID: 41090431). The first Phase 3 readout came in December 2025 from TRIUMPH-4, which tested retatrutide specifically in adults with obesity and knee osteoarthritis. Topline results showed 28.7% average body weight loss at 68 weeks (26.6% placebo-adjusted, approximately 71.2 pounds) at the 12 mg dose — peer-reviewed publication pending. The trial also demonstrated a 75.8% reduction in knee osteoarthritis pain scores, with one in eight participants becoming completely free of knee pain. However, TRIUMPH-4 also revealed a new safety signal not seen in Phase 2: dysesthesia (abnormal sensations of touch), occurring in 8.8% of participants at 9 mg and 20.9% at 12 mg versus 0.7% on placebo. While generally mild and infrequently leading to discontinuation, this finding is being closely monitored in subsequent TRIUMPH readouts. Seven additional Phase 3 readouts are expected throughout 2026, including data on obstructive sleep apnea and cardiovascular disease populations. If results remain positive, Eli Lilly is projected to submit a New Drug Application to the FDA in late 2026, with potential approval in the first half of 2027. Retatrutide is not currently available by prescription, through compounding pharmacies, or from research peptide vendors — the FDA has explicitly stated it cannot be legally compounded.
AOD-9604
metabolic
AOD-9604 is a modified fragment of human growth hormone (hGH fragment 176-191) that stimulates fat breakdown without the growth-promoting effects of full HGH.
MOTS-c
metabolic
MOTS-c is a mitochondrial-derived peptide that regulates metabolic homeostasis and has been called an "exercise mimetic" for its ability to activate AMPK pathways.
Tesamorelin
gh-secretagogue
Tesamorelin (brand name Egrifta) is a stabilized synthetic analog of growth hormone-releasing hormone (GHRH) and the only FDA-approved GH secretagogue currently on the market. The FDA approved it in November 2010 for reducing excess abdominal fat in HIV-infected patients with lipodystrophy, a condition where antiretroviral therapy redistributes fat from the limbs to the abdomen and trunk. This approval rests on two pivotal Phase 3 trials published in the New England Journal of Medicine showing tesamorelin produced a 15-18% reduction in visceral adipose tissue (VAT) compared to placebo over 26 weeks (PMID: 20395564). Tesamorelin is a 44-amino acid peptide, identical in length to endogenous GHRH, with a trans-3-hexenoic acid modification on the N-terminus that slows enzymatic degradation and extends its half-life. Unlike sermorelin (29 amino acids) or CJC-1295 (which extends half-life through albumin binding), tesamorelin achieves its stability through chemical modification of the peptide backbone itself. It acts exclusively on the GHRH receptor (GHRHR) using the same mechanism as endogenous GHRH, stimulating pituitary somatotrophs to release GH in the body's natural pulsatile pattern while preserving the somatostatin feedback loop. Beyond its approved lipodystrophy indication, tesamorelin has been studied in two additional populations: healthy older adults and patients with mild cognitive impairment (MCI). A large NIH-funded 152-subject RCT found that 20 weeks of tesamorelin significantly improved executive function (P = 0.005) across both healthy aging and MCI groups, with no worsening of glucose tolerance in non-diabetic subjects (PMID: 22869065). A separate RCT found it significantly increased muscle density and lean muscle area across four trunk muscle groups in HIV patients compared to placebo (PMID: 31237318). These findings have driven off-label interest in anti-aging and cognitive health applications.
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Recommended stacks
GLP-1 Weight Loss Stack
beginner — $200-600 (compounded) or $1,000+ (brand)
The foundational weight loss protocol using GLP-1 receptor agonists with muscle preservation support. The most evidence-backed approach to significant weight loss.
Dual Agonist Fat Loss Stack
intermediate — $300-800
Tirzepatide-based protocol leveraging dual GLP-1/GIP receptor activation for maximum weight loss with metabolic support.
Weight Loss + Healing Combo
intermediate — $300-700
For people who need to lose weight but also have injuries or joint pain that limit exercise. Addresses both simultaneously.
The Weight Loss Stack
intermediate — $400-1,200
Combines the appetite-suppressing power of semaglutide with tesamorelin's targeted visceral fat reduction. Semaglutide reduces caloric intake through GLP-1 receptor activation while tesamorelin specifically targets the deep abdominal fat linked to metabolic disease.
The Fat Loss Stack
advanced — $350-700
A triple-compound approach to fat loss that works through three distinct mechanisms: AOD-9604 mimics the fat-burning fragment of growth hormone, tesamorelin targets visceral fat through GHRH receptor activation, and MOTS-c optimizes mitochondrial metabolism.
The GLP-1 Recovery Stack
beginner — $300-900
Combines tirzepatide's dual-agonist weight loss power with BPC-157 gut protection. The most common side effects of GLP-1 medications are gastrointestinal. BPC-157 directly addresses nausea, GERD, and gut discomfort during dose escalation.
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Written by Alejandro Reyes
Founder & Lead Researcher
Reviewed by Peptide Nerds Editorial · Updated April 2026