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What people use peptides for

Peptides for weight loss: what actually works

Weight loss is where peptides have the strongest evidence by far. Tirzepatide and semaglutide are approved medicines tested in thousands of people. Others, like AOD-9604 and MOTS-c, are sold online with little to back them up.

By Cited Peptides Editorial Updated Medical review pending

This page has not yet been reviewed by a credentialed medical professional. It is educational and is not medical advice.

The short answer

The approved GLP-1 medicines have large randomized trials behind them. Retatrutide has strong phase 3 results but is not approved yet. Most other "fat loss" peptides have little or no human evidence.

What people use, ranked by evidence

Strongest evidence first. The numbers come live from PubMed and ClinicalTrials.gov.

  1. Tirzepatide

    FDA-approved

    What people use it for: Weight loss and type 2 diabetes. Dual GIP/GLP-1 agonist.

    What the evidence says: Approved for type 2 diabetes and chronic weight management, with large randomized trials and a head-to-head against semaglutide.

    133 randomized trials 298 registered trials Approved for: Type 2 diabetes and chronic weight management; sleep apnea Sport: Not prohibited
    Tirzepatide profile →

  2. Semaglutide

    FDA-approved

    What people use it for: Weight loss and type 2 diabetes. One of the most prescribed drugs in the world.

    What the evidence says: Approved for type 2 diabetes and chronic weight management, with large randomized trials including a cardiovascular outcomes trial.

    311 randomized trials 779 registered trials Approved for: Type 2 diabetes and chronic weight management; heart-risk reduction Sport: Not prohibited
    Semaglutide profile →

  3. Liraglutide

    FDA-approved

    What people use it for: Weight loss (Saxenda) and type 2 diabetes (Victoza). A daily GLP-1 drug that came before semaglutide.

    What the evidence says: Approved, with large randomized trials. Semaglutide beat it head-to-head for weight loss.

    561 randomized trials 514 registered trials Approved for: Type 2 diabetes; chronic weight management Sport: Not prohibited
    Liraglutide profile →

  4. Retatrutide

    Human trials

    What people use it for: Weight loss and type 2 diabetes. A triple GIP/GLP-1/glucagon agonist with positive phase 3 results that is not approved yet, but is widely sold online anyway.

    What the evidence says: Phase 2 and phase 3 clinical trials demonstrate up to 24% weight loss in adults with obesity and significant HbA1c reductions in type 2 diabetes. Unapproved; Lilly plans FDA submission in 2027.

    8 randomized trials 33 registered trials Not approved as a medicine Sport: Check list
    Retatrutide profile →

  5. Tesamorelin

    FDA-approved

    What people use it for: Reducing abdominal fat in HIV lipodystrophy (the approved use); promoted off-label for body composition.

    What the evidence says: FDA-approved as Egrifta for reducing excess visceral abdominal fat in HIV-associated lipodystrophy. Clinical trials demonstrate selective visceral fat reduction without lowering subcutaneous fat.

    21 randomized trials 24 registered trials Approved for: Excess abdominal fat in HIV-associated lipodystrophy Sport: Prohibited
    Tesamorelin profile →

  6. AOD-9604

    Animal studies only

    What people use it for: Fat loss. A fragment of growth hormone sold as a "fat burner".

    What the evidence says: Little published human data and no randomized trials found on PubMed. Sold online as a research chemical without approval.

    0 randomized trials 0 registered trials Not approved as a medicine Sport: Prohibited
    AOD-9604 profile →

  7. MOTS-c

    Animal studies only

    What people use it for: Metabolism, exercise capacity and "longevity". A peptide encoded by mitochondrial DNA.

    What the evidence says: Mostly mouse and cell studies. The few human "trials" on PubMed measured the body's own MOTS-c levels after exercise, not MOTS-c as a treatment.

    4 randomized trials 5 registered trials Not approved as a medicine Sport: Check list
    MOTS-c profile →

Common questions

Which peptide works best for weight loss?

In the one head-to-head obesity trial (SURMOUNT-5), tirzepatide produced more average weight loss than semaglutide: -20.2% vs -13.7% at 72 weeks. Individual results vary.

Is retatrutide approved?

No. Phase 3 (TRIUMPH) results were reported in 2026, and Eli Lilly says it plans to file with the FDA in the first quarter of 2027. Versions sold online now are not approved medicines.

Do "research" GLP-1 peptides work the same as the real thing?

There is no way to know what an unregulated product contains. Health Canada has seized unauthorized injectable peptides including retatrutide and warns they can contain the wrong dose or contaminants.

Go deeper

ComparisonSemaglutide vs Tirzepatide ToolWeight loss calculatorToolMedication cost calculatorToolAll weight loss medications compared

Other goals

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"What people use it for" describes common claims, not recommendations. Educational only, not medical advice.