Weight Loss Peptides
The definitive guide · 12 compounds · Updated February 2026
From FDA-approved GLP-1 agonists to emerging triple-receptor compounds, this guide covers every peptide used for weight management — with mechanisms of action, clinical evidence, safety profiles, dosing protocols, and how to find trusted sources.
GLP-1 Receptor Agonists
The gold standard — FDA-approved with the strongest clinical evidence
Semaglutide
Also known as: Ozempic, Wegovy, Rybelsus
How It Works
Mimics GLP-1 hormone to reduce appetite, slow gastric emptying, and improve insulin sensitivity. Acts on hypothalamic appetite centers to produce satiety.
Side Effects
- •Nausea (most common, usually transient)
- •Vomiting
- •Diarrhea/Constipation
- •Abdominal pain
- •Headache
- •Injection site reactions
Best For
- ✓Obesity (BMI ≥30)
- ✓Overweight with comorbidities
- ✓Type 2 diabetes + weight loss
- ✓Long-term weight management
Liraglutide
Also known as: Saxenda, Victoza
How It Works
First GLP-1 agonist approved for weight management. Shorter-acting than semaglutide, requires daily dosing. Well-established safety profile with years of clinical use.
Side Effects
- •Nausea
- •Diarrhea
- •Constipation
- •Vomiting
- •Low blood sugar
- •Injection site reactions
Best For
- ✓Moderate weight loss goals
- ✓Those preferring established safety data
- ✓Adolescent obesity (age 12+)
- ✓Step-down from semaglutide
Dual & Triple Agonists
Next-gen multi-receptor targeting for enhanced results
Tirzepatide
Also known as: Mounjaro, Zepbound
How It Works
First-in-class dual incretin agonist targeting both GLP-1 and GIP receptors. GIP receptor activation enhances fat oxidation and energy expenditure beyond GLP-1 alone.
Side Effects
- •Nausea
- •Diarrhea
- •Decreased appetite
- •Vomiting
- •Constipation
- •Injection site reactions
Best For
- ✓Maximum weight loss potential
- ✓Obesity (BMI ≥30)
- ✓Type 2 diabetes + obesity
- ✓Metabolic syndrome
Growth Hormone Peptides
Body recomposition through natural GH stimulation
Tesamorelin
Also known as: Egrifta
How It Works
Stimulates pituitary to release growth hormone naturally. Specifically targets visceral (belly) fat reduction while preserving muscle mass. Does not suppress natural GH production.
Side Effects
- •Injection site reactions
- •Joint pain
- •Muscle pain
- •Swelling of extremities
- •Tingling/numbness
Best For
- ✓Visceral fat specifically
- ✓HIV-associated lipodystrophy
- ✓Stubborn belly fat
- ✓Those wanting GH benefits without exogenous GH
CJC-1295 + Ipamorelin
Also known as: CJC-1295/DAC, Modified GRF 1-29
How It Works
Synergistic stack: CJC-1295 stimulates GH release via GHRH pathway while ipamorelin triggers GH pulse via ghrelin receptor. Together they amplify natural GH production for fat loss and body recomposition.
Side Effects
- •Water retention (transient)
- •Tingling/numbness
- •Increased hunger
- •Headache
- •Flushing
Best For
- ✓Body recomposition goals
- ✓Those wanting GH benefits
- ✓Anti-aging + fat loss combo
- ✓Athletes and fitness enthusiasts
Metabolic & Novel Peptides
Unique mechanisms — NNMT inhibition, mitochondrial, gut-brain
AOD 9604
Also known as: Anti-Obesity Drug Fragment, hGH Fragment 176-191
How It Works
Isolated fat-burning fragment of growth hormone. Stimulates lipolysis (fat breakdown) and inhibits lipogenesis (fat formation) without the growth-promoting or diabetogenic effects of full GH.
Side Effects
- •Injection site reactions
- •Headache
- •Generally well-tolerated in trials
- •Limited long-term safety data
Best For
- ✓Targeted fat loss without GH side effects
- ✓Those concerned about GH-related risks
- ✓Complement to diet/exercise
- ✓Research applications
MOTS-c
Also known as: Mitochondrial ORF of the 12S rRNA Type-c
How It Works
Encoded within mitochondrial DNA. Activates AMPK pathway (the "exercise switch"), improves insulin sensitivity, enhances fatty acid oxidation, and mimics some metabolic effects of exercise.
Side Effects
- •Very limited human safety data
- •Injection site reactions reported
- •Theoretical: metabolic stress
Best For
- ✓Metabolic dysfunction research
- ✓Insulin resistance
- ✓Exercise mimetic applications
- ✓Early adopters comfortable with limited data
5-Amino-1MQ
Also known as: 5-amino-1-methylquinolinium
How It Works
Inhibits NNMT enzyme which is overexpressed in fat tissue. Blocking NNMT increases cellular energy expenditure, activates fat cell metabolism, and reduces lipid accumulation. Oral availability is a major advantage.
Side Effects
- •Very limited human safety data
- •Theoretical: liver/kidney effects
- •Nausea reported anecdotally
Best For
- ✓Those preferring oral peptides (no injections)
- ✓Metabolic research
- ✓NNMT-related metabolic dysfunction
- ✓Experimental/early-adopter profile
BPC-157
Also known as: Body Protection Compound-157, Pentadecapeptide
How It Works
Derived from human gastric juice protein. Primarily known for tissue healing, but emerging research shows effects on gut microbiome, gut-brain axis signaling, and metabolic regulation. May enhance weight loss indirectly through improved gut health and nutrient partitioning.
Side Effects
- •Generally well-tolerated
- •Nausea (uncommon)
- •Dizziness (rare)
- •Limited long-term human data
Best For
- ✓Gut health optimization
- ✓GLP-1 side effect management
- ✓Complementary to primary weight loss peptides
- ✓Tissue healing + metabolic support
Pipeline & Emerging
In clinical trials — not yet commercially available
Retatrutide
Also known as: LY3437943, Triple G (GGG agonist)
How It Works
First triple agonist targeting GLP-1, GIP, AND glucagon receptors. Glucagon component adds thermogenesis and hepatic fat reduction. In Phase 3 trials — potentially the most effective weight loss peptide ever studied.
Side Effects
- •Nausea
- •Diarrhea
- •Vomiting
- •Constipation
- •Similar GI profile to GLP-1s
Best For
- ✓Maximum possible weight loss
- ✓Those monitoring pipeline compounds
- ✓Metabolic syndrome research
- ✓Not yet available commercially
Survodutide
Also known as: BI 456906
How It Works
Unlike tirzepatide (GLP-1/GIP), survodutide pairs GLP-1 with glucagon receptor activation. Glucagon component increases energy expenditure and reduces liver fat — promising for NASH/MAFLD.
Side Effects
- •Nausea
- •Diarrhea
- •Vomiting
- •Similar to GLP-1 class
Best For
- ✓Liver fat reduction + weight loss
- ✓NASH/MAFLD research
- ✓Those monitoring pipeline
- ✓Not yet available commercially
Tesofensine
Also known as: NS2330
How It Works
Originally developed for Parkinson's/Alzheimer's. Works centrally to reduce appetite and increase thermogenesis via triple neurotransmitter reuptake inhibition. Different mechanism from all other weight loss peptides.
Side Effects
- •Dry mouth
- •Insomnia
- •Constipation
- •Increased heart rate
- •Mood changes
- •Elevated blood pressure
Best For
- ✓Those who cannot tolerate GLP-1s
- ✓Oral preference (no injections)
- ✓Appetite-driven overeating
- ✓Research applications
📊 Head-to-Head Comparison
How the top weight loss peptides stack up against each other
| Peptide | Mechanism | Weight Loss | Safety | Status | Frequency |
|---|---|---|---|---|---|
💊 Semaglutide Ozempic | GLP-1 Receptor Agonist | ~15% body weight | 9/10 | FDA Approved | Once weekly injection |
🎯 Tirzepatide Mounjaro | Dual GLP-1/GIP Receptor Agonist | ~22.5% body weight | 9/10 | FDA Approved | Once weekly injection |
💉 Liraglutide Saxenda | GLP-1 Receptor Agonist | ~8% body weight | 9/10 | FDA Approved | Daily injection |
🚀 Retatrutide LY3437943 | Triple Incretin Receptor Agonist | ~24.2% body weight (highest dose) | 7/10 | Phase 3 Clinical Trials | Once weekly injection |
🔮 Survodutide BI 456906 | Dual GLP-1/Glucagon Receptor Agonist | ~18.7% body weight | 6/10 | Phase 3 Clinical Trials | Once weekly injection |
🧠 Tesofensine NS2330 | Serotonin/Norepinephrine/Dopamine Reuptake Inhibitor | ~10-13% body weight | 5/10 | Phase 3 (Outside US) | Daily oral capsule |
🛒 How People Buy Peptides
Understanding the different paths to accessing weight loss peptides
Prescription (Telehealth)
FDA-approved brand-name peptides (Wegovy, Mounjaro, Saxenda) via telehealth consultations or your doctor. Insurance may cover.
Compounding Pharmacies
Custom-compounded versions of approved peptides. Often more affordable. Still requires prescription but typically through affiliated providers.
Research Chemical Vendors
Research-use peptides from specialty vendors. No prescription needed. Sold "for research only." This is where most non-FDA-approved peptides are sourced.
What to Look for When Choosing a Vendor
Third-Party COAs
Certificates of Analysis from independent labs verifying purity (≥98%) and identity
HPLC/Mass Spec Testing
High-performance liquid chromatography confirms peptide identity and purity
Transparent Business
Real business address, responsive customer service, clear return policy
Community Reputation
Verified reviews, community forum presence, established track record (1+ years)
Find Verified Peptide Vendors
We review and verify peptide vendors based on third-party testing, pricing transparency, customer reviews, and shipping reliability.
❓ Frequently Asked Questions
What is the most effective peptide for weight loss?
Based on clinical trial data, tirzepatide (Mounjaro/Zepbound) produces the highest weight loss at approximately 22.5% of body weight over 72 weeks. Retatrutide, still in Phase 3 trials, has shown up to 24.2% in Phase 2 data. Among widely available options, semaglutide (Wegovy) at ~15% body weight loss remains the most prescribed.
Are weight loss peptides safe?
FDA-approved GLP-1 agonists (semaglutide, tirzepatide, liraglutide) have extensive safety data from trials involving tens of thousands of participants. The most common side effects are gastrointestinal (nausea, usually temporary). Research-only peptides like AOD 9604 and MOTS-c have significantly less safety data. Always consult a healthcare provider before starting any peptide protocol.
What is the difference between semaglutide and tirzepatide?
Semaglutide targets GLP-1 receptors only. Tirzepatide targets both GLP-1 and GIP receptors (dual agonist), which provides additional metabolic benefits. Clinical trials show tirzepatide produces roughly 50% greater weight loss than semaglutide. Both are given as weekly injections.
Can I buy peptides without a prescription?
FDA-approved peptides (semaglutide, tirzepatide, liraglutide) require a prescription. Research peptides (AOD 9604, MOTS-c, CJC-1295, 5-Amino-1MQ) are sold by research chemical vendors without a prescription, labeled "for research purposes only." Compounded versions of approved peptides require a prescription through affiliated providers.
How do I know if a peptide vendor is trustworthy?
Look for: (1) Third-party Certificates of Analysis (COAs) from independent labs, (2) HPLC and mass spectrometry testing results, (3) Transparent business information and customer service, (4) Positive community reviews on independent forums. We review and verify vendors on our Vendors page.
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Medical Disclaimer
This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment. Peptides discussed here range from FDA-approved medications to research-only compounds. Always consult with a qualified healthcare provider before starting any peptide protocol. Research-only peptides are not approved for human consumption. Peptok does not sell peptides.