Best Peptides for Fat Loss 2026: Ranked by the Strength of Published Data

In short

The honest ranking of the best peptides for fat loss is not a ranking of percentages. It is a ranking of how much evidence sits behind each percentage. A 24.2 % result from 338 participants in a phase 2 trial and a 20.9 % result from 2 539 participants in phase 3 are not the same claim, even though the first number looks better.

• Strongest published evidence: tirzepatide, the cagrilintide plus GLP-1 analogue combination, and mazdutide, all with completed phase 3 trials
• Largest single percentage, weaker denominator: retatrutide, at 24.2 % over 48 weeks in a phase 2 trial of 338 adults
• Amylin is the newest mechanism in the class, and cagrilintide is the molecule carrying it
• Where the evidence runs out: AOD-9604, HGH Fragment 176-191, 5-Amino-1MQ and MOTS-c have no published phase 2 or phase 3 weight outcome in humans
• Price per milligram across the class runs from about 7 € to 24 €, and it tracks synthesis difficulty, not efficacy
• Everything here is laboratory research material. Not a medicine, not a supplement, not for human or animal consumption

The ranking: best peptides for fat loss by evidence tier

Ranked by the strength of published human data rather than by headline percentage, the order is: tirzepatide and the cagrilintide combination first, mazdutide next, then retatrutide and survodutide on phase 2 data, then cagrilintide as monotherapy, and finally a group of compounds with no published human weight outcome at all. Every figure below comes from a named, indexed trial with its sample size attached.

Semaglutide belongs in this comparison as a reference point, with 14.9 % over 68 weeks in 1 961 participants in STEP 1 (PubMed 33567185), but it is a prescription medicine and Molequa® does not sell it in any form. It appears here only because almost every trial in the class is positioned against it.

The mechanistic explanation of how these molecules act, rather than how strong their evidence is, sits in the companion pillar on peptides for weight loss. This article deliberately stays on the evidence question.

Why the biggest percentage is not the best result

Retatrutide has the highest published weight reduction in the class at 24.2 %, and it also has the smallest supporting sample among the front runners. The phase 2 trial enrolled 338 adults over 48 weeks (PubMed 37366315). Tirzepatide’s 20.9 % came from 2 539 participants over 72 weeks in a completed phase 3 programme (PubMed 35658024). Larger samples and longer follow-up shrink the gap between an early signal and a durable effect.

Three things separate a phase 2 number from a phase 3 number, and none of them are visible in the percentage itself.

The first is regression. Early trials run in smaller, more selected populations, and effect sizes in that setting routinely soften when the same molecule is tested in thousands of people across dozens of sites. The second is duration. A 48-week readout and a 72-week readout answer different questions, because weight curves in this class typically continue to separate from placebo well past the one-year mark. The third is discontinuation. Larger and longer trials accumulate more dropouts, and how a trial handles those dropouts in its statistical estimand can move the headline number by several percentage points on its own.

None of this makes retatrutide a weaker molecule. It makes 24.2 % a less settled number than 20.9 %. For a laboratory choosing reference material, that distinction matters more than the ranking order, because it determines what the comparison in your own protocol is actually being benchmarked against. The direct head to head of the two molecules is laid out in retatrutide vs tirzepatide.

GLP-1 peptides for weight loss: what adding receptors actually buys

GLP-1 peptides for weight loss now come in one, two and three receptor versions, and the published data show a real but non-linear gain from adding targets. Single-receptor semaglutide reached 14.9 %, dual-receptor tirzepatide 20.9 %, and triple-receptor retatrutide 24.2 % in its phase 2 readout. The jump from one to two receptors is larger than the jump from two to three, and the third target brings its own tolerability profile.

The mechanistic logic is straightforward. GLP-1 and GIP are both incretins released from the gut, and they act on separate receptor families, so co-agonism recruits two partly independent satiety and glycaemic pathways rather than pushing harder on one. Glucagon receptor agonism, the third arm in retatrutide and the second arm in survodutide, works from a different direction again: it is associated in the literature with energy expenditure rather than with appetite suppression.

Amylin is the newest addition and it is not an incretin at all. Cagrilintide is a long-acting amylin analogue acting on amylin and calcitonin receptors, and in phase 2 monotherapy over 26 weeks it produced reductions of 6.0 % to 10.8 % across doses versus 3.0 % on placebo, in 906 randomised participants (PubMed 34798060). Combined with a GLP-1 analogue in the phase 3 REDEFINE 1 trial, the pairing reached 20.4 % at week 68 in 3 417 participants (PubMed 40544433). The background on that molecule is in the cagrilintide guide.

Two more dual agonists complete the picture. Mazdutide, a GLP-1 and glucagon receptor dual agonist, reported 12.55 % at week 32 on the 6 mg dose versus 0.45 % on placebo among 610 participants in a phase 3 trial in China (PubMed 40421736). Survodutide, also glucagon and GLP-1, reported 14.9 % at week 46 on the highest dose versus 2.8 % on placebo in a phase 2 dose-finding trial of 386 treated participants (PubMed 38330987). A 2025 systematic review in Pharmacological Reviews covers the wider emerging pipeline (PubMed 39952695).

Across all of these trials the adverse events reported were predominantly gastrointestinal and mostly mild to moderate, concentrated during dose escalation. Those observations come from supervised clinical trials and describe the molecules under medical monitoring, not the research material sold in any catalogue.

Where the evidence runs out: the fat loss peptides with no human trial

Four compounds appear constantly in fat loss discussions and have no published phase 2 or phase 3 weight outcome in humans: AOD-9604, HGH Fragment 176-191, 5-Amino-1MQ and MOTS-c. Their research base is mouse and cell work, sometimes strong mechanistic work, but the translational step has not been published. Ranking them alongside the incretin class is a category error.

5-Amino-1MQ is a small molecule rather than a peptide, and it inhibits nicotinamide N-methyltransferase. The primary citation is a 2018 paper in Biochemical Pharmacology reporting that selective, membrane-permeable NNMT inhibitors reversed high fat diet-induced obesity in mice (PubMed 29155147). That is a genuine and interesting preclinical result. It is also, as of 2026, the extent of it.

MOTS-c is a 16-amino-acid mitochondrially encoded peptide first described in 2015 in Cell Metabolism, where it was reported to promote metabolic homeostasis and reduce obesity and insulin resistance in mouse models (PubMed 25738459). Again a mouse model, again no published human weight outcome.

AOD-9604 is the modified C-terminal fragment of human growth hormone. The clearest thing that can be said about its published record is how thin it is: a 2004 pipeline entry in Current Opinion in Investigational Drugs notes that phase IIa trials were under way as of February 2002 (PubMed 15134286). More than two decades later there is no indexed phase 2 weight outcome to cite. HGH Fragment 176-191 sits in the same position, and the two names are frequently used interchangeably in retail listings even though they refer to different preparations.

This is not an argument against holding these compounds as reference material. It is an argument against putting them in the same ranking column as a molecule with 3 417 randomised participants behind it.

Peptides for weight loss in the UK and the EU: what buyers should check

For a UK-based laboratory the practical question is no longer legality alone but customs. Since Brexit, an order shipped from an EU warehouse to a UK address crosses a customs border, which adds import VAT, possible handling fees and unpredictable transit time for temperature-sensitive lyophilised material. For a laboratory inside the EU, the same order moves without customs clearance, typically in one to three working days.

The compliance framing is identical on both sides of the border: these compounds are traded as research chemicals under Research Use Only labelling, they are not authorised medicines, and they are not supplements or cosmetics. None of the molecules in the tiers above is approved for human use, with the exception of the reference comparators that exist as prescription medicines under other names and are not sold here.

The full legal and customs breakdown for UK buyers, including what changed after Brexit and how import VAT is applied, is set out in the guide to research peptides in the UK.

Price per milligram across the class

Price in this class tracks synthesis difficulty, not efficacy. The long, acylated incretin molecules sit between 12 € and 24 € per milligram, while short unmodified peptides sit near 7 €. A cheaper molecule is not a weaker one, and an expensive one is not better evidenced. Retatrutide and mazdutide cost the same per milligram despite standing in different evidence tiers.

Every added amino acid in solid-phase synthesis is another coupling cycle with its own yield loss, and every fatty-acid acylation is an extra chemical step with its own purification. A 15-residue unmodified peptide and a 39-residue acylated one are not comparable manufacturing problems, and the price reflects that and nothing else.

The only comparable figure between suppliers is the price per milligram. A vial price on its own says nothing, because vials contain different amounts.

Where to buy research peptides for metabolic work

Molequa® supplies these molecules as lyophilised powder in a vial, with declared HPLC purity of at least 99 %, mass spectrometry identity confirmation and a batch-specific certificate of analysis issued by the independent laboratory Janoshik Analytical. Shipping leaves from inside the EU, without customs clearance for EU destinations and typically within one to three working days.

Current price per milligram, batch certificate and availability for the highest-evidence triple agonist are on the product page for retatrutide. The per-milligram breakdown for the rest of the class is in the research peptides catalogue, and the supplier verification procedure that applies before ordering from anyone is set out in how to verify a peptide supplier.

Before paying, the thirty-second check is always the same: batch certificate available without asking, chromatogram attached, independent laboratory named, EU warehouse, and delivery as lyophilised powder in a vial rather than any pre-filled format.

Frequently asked questions

Which peptide has the strongest fat loss data?

By sample size and trial phase, tirzepatide and the cagrilintide plus GLP-1 analogue combination. Tirzepatide reported 20.9 % over 72 weeks in 2 539 participants, and the cagrilintide combination reported 20.4 % over 68 weeks in 3 417 participants, both in completed phase 3 trials. Retatrutide reported a higher figure at 24.2 %, but from 338 participants in phase 2, which is a less settled result.

Are the best peptides for weight loss the same as the best for fat loss?

In the published literature the two questions have the same answer, because trials measure total body weight rather than fat mass specifically. Body composition endpoints appear in some substudies but are not the primary outcome in the large trials, so any claim that one molecule preferentially spares lean mass is currently weaker evidence than the headline weight numbers.

Do GLP-1 peptides for weight loss work better with more receptors?

The published data suggest a real but non-linear gain. Single-receptor semaglutide reached 14.9 %, dual-receptor tirzepatide 20.9 %, and triple-receptor retatrutide 24.2 % in phase 2. The step from one to two receptors is larger than the step from two to three, and the additional targets bring their own tolerability considerations.

Do AOD-9604 and MOTS-c have human fat loss data?

No published phase 2 or phase 3 weight outcome exists for either. MOTS-c rests on a 2015 mouse study in Cell Metabolism, and the clearest published record for AOD-9604 is a 2004 pipeline note stating that phase IIa trials were under way in 2002, with no indexed outcome publication since.

Why is retatrutide more expensive than tirzepatide if both are 39 amino acids?

Chain length is only one input. Retatrutide carries a C20 fatty diacid acylation and its research demand currently exceeds supply, while tirzepatide has a more mature manufacturing base. Price in this class reflects synthesis difficulty and supply maturity, never trial results.

Can these peptides be bought legally in the UK or the EU?

Trading reference material for laboratory research is not prohibited, but the substances may not be presented or used as medicines, supplements or cosmetics. None of the research molecules listed here is authorised as a medicine by any regulator. Responsibility for checking that the intended use complies with applicable rules rests with the buyer.

Why do you not publish dosing information?

Because these materials are not intended for human use. Publishing a human administration schedule would contradict the RUO framework under which they are legally sold. A supplier who provides one alongside the price is signalling that the rest of their operation does not respect that framework either.

Legal notice

All Molequa® products are intended exclusively for scientific laboratory research (Research Use Only). They are not medicines, food supplements, cosmetics or foods, and they are not intended for human or animal consumption or for application to the skin of humans or animals. Retatrutide, cagrilintide, survodutide, mazdutide, 5-Amino-1MQ, MOTS-c and AOD-9604 are not authorised as medicines in any jurisdiction. The scientific data cited in this article come from published literature and describe clinical research conducted with the corresponding substances under medical supervision; they are not a claim about the products sold and not a recommendation for use. Prices reflect September 2026 and may change; the product page price is always authoritative.