How This Guide Is Organized
Compounds here are ranked by quality and quantity of evidence — prioritizing human clinical trial data, then animal models, with anecdotal reports noted but not used for ranking. Legal status is included because it directly affects what research pathways are available. The goal is an honest picture of where the science actually is, not where the marketing wants you to think it is.
Tier 1: FDA-Approved — Strong Human Trial Evidence
Semaglutide (Ozempic/Wegovy) and Tirzepatide (Mounjaro/Zepbound) are the undisputed gold standard. Semaglutide's STEP trial program showed average weight loss of 14.9% over 68 weeks in adults with obesity. Tirzepatide's SURMOUNT-1 trial showed up to 22.5% weight loss at the highest dose — the largest effect size ever recorded in a phase 3 obesity trial. Both require a prescription. Both require ongoing use to maintain results — discontinuation leads to significant weight regain, as the STEP 4 extension clearly showed.
Tier 2: Prescription-Accessible, Moderate Evidence
Tesamorelin has FDA approval specifically for HIV-associated lipodystrophy and is the most evidence-backed GHRH analogue for fat reduction in a specific population. CJC-1295 and Sermorelin can be prescribed off-label for GH optimization, with body composition as a secondary benefit — GH has real lipolytic effects, and IGF-1 elevation correlates with reduced adiposity, but the effect size is significantly smaller than GLP-1 agonists. These are not weight loss drugs; they are GH optimization tools that may have favorable body composition effects.
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Tier 3: Research Chemicals — Animal Data Only
AOD-9604 is a fragment of the HGH molecule (amino acids 177–191) specifically designed to retain HGH's fat-metabolizing properties. Early Australian trials showed promise, but phase 3 trials did not demonstrate the efficacy needed for FDA approval. It is not approved and is sold only as a research chemical. Fragment 176-191 and related compounds have essentially no completed human trial data. MOTS-c, a mitochondrial peptide, is at an even earlier stage — compelling rodent data, essentially no human evidence. The animal mechanistic data for these compounds is genuinely interesting; the clinical evidence is not yet there.
What the Evidence Gap Actually Means
The fat loss peptide landscape has a stark dividing line. GLP-1 agonists (semaglutide, tirzepatide) have overwhelming human clinical evidence and produce weight loss that no other peptide class approaches by an order of magnitude. Everything else is either modest-effect or experimental. If fat loss is the primary research goal, the intellectually honest answer is that the FDA-approved GLP-1 class is in a category by itself. Research chemical alternatives are worth monitoring as the science develops — but claiming equivalence with the tier 1 evidence base would misrepresent what the data currently shows.