Weight management

Weight management is the area where peptide science has produced its most striking, best-evidenced results, and also some of its most overhyped research chemicals. The contrast between the two is the most useful thing to understand here.

On the strong-evidence side are the incretin medicines: Semaglutide (a GLP-1 receptor agonist) and Tirzepatide (a dual GIP/GLP-1 agonist) are approved by the FDA and EMA for chronic weight management, with large randomized trials behind them. Retatrutide, a triple agonist, has shown even larger weight loss in trials, but it is investigational and not approved, available only within clinical studies.

On the weaker-evidence side, AOD-9604 — a growth-hormone fragment once developed as an obesity drug — failed to show significant weight loss versus placebo in its human trials and was discontinued for that use. Tesamorelin reduces visceral fat but only in its narrow approved HIV-lipodystrophy indication.

Each entry below covers mechanism, trial results (including negative ones), approval status, and risks.

Conditions people ask about

Popular videos in this area promise to "reverse," "fix at the root," or "cure" metabolic conditions with a peptide protocol — that framing goes beyond what the completed, published evidence we could review supports. No compound on this site is an approved treatment for any condition below, and the dramatic reversal percentages such content cites have not been matched to completed controlled human evidence for the named condition in the sources we were able to search. A caution on that last point: not finding a supporting trial here is not proof that a claim is false — a great deal of relevant work (paywalled journals, regional literature, clinical practitioner experience, conference abstracts, and unpublished or proprietary data) is simply not indexed in what we can reach, and absence of evidence is not evidence of absence. The notes below exist to answer common searches honestly, not to guide treatment: they say which of our compounds are discussed in each context and what their honest, presently-documented status is. Any of these conditions is a matter for a licensed clinician who can diagnose and stage it — a research peptide is not a substitute for that workup or for approved care.

Insulin resistance

High-claim content frames insulin resistance as something you can "reverse" or "fix at the root" with a peptide, positioning research compounds as insulin sensitizers that outperform standard care. What the documented picture shows is that insulin resistance is not a standalone disease with its own approved drug — it is a metabolic feature that appears within type 2 diabetes, prediabetes, PCOS and obesity, and the established prescription tools are approved for those diagnoses, not for "insulin resistance" as a target [Human]. Among our inventory, only the incretin drugs have controlled human data improving insulin-resistance markers, and only as a downstream effect of treating diabetes/obesity: tirzepatide is a GLP-1/GIP dual agonist approved for type 2 diabetes and obesity (not for insulin resistance itself) that reduced HOMA2-IR and improved beta-cell function in the SURPASS and SURMOUNT trials as an effect of glycemic/weight treatment [Human]; semaglutide, a GLP-1 agonist approved for type 2 diabetes and obesity, improves insulin-resistance markers within those indications but lowered HOMA-IR less than tirzepatide head-to-head in SURPASS-2, and is not indicated for insulin resistance as a diagnosis [Human]. The mitochondrial/metabolic-activator peptides marketed for this purpose do not yet have completed controlled human evidence that we could locate: MOTS-c improved insulin-stimulated glucose uptake and insulin sensitivity in rodent models and is widely marketed as an insulin sensitizer, but human efficacy has not been demonstrated in any completed trial we could find — a first Phase 2a trial in prediabetes/overweight only started around 2026 [Animal][Hypothesis]; 5-amino-1MQ is an NNMT inhibitor studied preclinically for fat mass and metabolic rate, and no controlled human trial testing it for insulin resistance surfaced in the literature we searched — which is a limit of what is indexed, not a verdict against it [Animal][In vitro]; and SLU-PP-332 is an ERR-agonist "exercise mimetic" that improved glucose handling in diet-induced-obese mice, with no human data located and preclinical-only status in the record we have [Animal][Hypothesis]. Suspected insulin resistance needs a licensed clinician and proper diagnosis (fasting glucose/insulin, HbA1c, OGTT) — a research peptide is not a substitute for that workup or for approved therapy.

Metabolic dysfunction / fatty liver (MASLD/MASH)

High-claim content presents fatty liver as fully "reversible" with a peptide, citing dramatic liver-fat clearance percentages as if any research peptide were a proven cure for MASLD or MASH. In reality MASLD (fatty liver) and its inflammatory/fibrotic form MASH are serious progressive liver conditions, and until recently there were no approved drugs at all — the first, resmetirom (not in our inventory), was FDA-approved for MASH with fibrosis only in March 2024 [Human]. Among our inventory, only semaglutide has an actual MASH approval: the Wegovy formulation received accelerated FDA approval in August 2025 for MASH with moderate-to-advanced fibrosis, based on the phase 3 ESSENCE trial — an approval for MASH with fibrosis, not a blanket "fatty liver" cure [Human]. The others people cite are investigational or narrowly indicated: retatrutide, an investigational triple GLP-1/GIP/glucagon agonist, cut liver fat by more than 80% relative at higher doses with steatosis resolution in most patients in a phase 2a MASLD trial, but it is not FDA-approved for any indication and long-term/fibrosis-endpoint data are still pending [Human, investigational]; tesamorelin, a GHRH analog approved only for HIV-associated visceral fat, showed reduced liver fat and less fibrosis progression over 12 months in a randomized trial — but that evidence is confined to HIV-associated NAFLD and it is not approved for general MASLD/MASH [Human, narrow]; and tirzepatide, approved for type 2 diabetes and obesity, reduces liver fat as a metabolic effect and is being studied in MASH, but here it is discussed for fatty liver rather than approved for it [Human]. Dramatic "reversal" framing outruns a still-emerging evidence base and ignores that MASH is diagnosed and staged by a hepatologist (imaging, elastography, sometimes biopsy) — a research peptide is not a substitute for that diagnosis or for licensed care.

Muscle and lean-mass loss on GLP-1s

This concern is real and worth taking seriously — but the popular "fix" for it is backwards, and that is the dangerous part. Body-composition sub-studies confirm that some of the weight lost on GLP-1 drugs is lean (fat-free) mass: roughly 25–40% across trials — about 40% of the loss in the semaglutide STEP 1 DEXA sub-study, and closer to 25% (a ~3:1 fat-to-lean ratio) for tirzepatide in SURMOUNT-1 [Human]. Measurable bone-mineral-density loss has also been documented (a 52-week semaglutide trial found hip and spine BMD fell ~2–2.6% versus placebo; Hansen et al., eClinicalMedicine 2024) [Human]. So the phenomenon is genuine — though the widely-shared "over half your weight loss is muscle" figure overstates the typical ~25–40%, and for semaglutide the lean share of body mass actually improved. Note too that human skeletal muscle does not appear to express a functional GLP-1 receptor, so the loss is best explained by the caloric deficit itself, not a direct drug effect on muscle — and the claim that retatrutide uniquely "spares 40% more muscle" than tirzepatide could not be traced to a real study and is contradicted by the phase-2 comparison, which found no muscle-sparing advantage (Coskun et al., Lancet Diabetes Endocrinol 2025) [Human].

The claim to be careful about is "protein is irrelevant — the ubiquitin-proteasome system breaks muscle down regardless, so take BCAAs or leucine instead." The muscle-atrophy machinery it invokes (the E3 ligases MAFbx/MuRF1) is real biology — but it was characterised in rodent denervation and cachexia models (Bodine et al., Science 2001, not the journal usually cited), not in GLP-1 therapy, and there is no evidence GLP-1 drugs drive it independently of protein intake. The mainstream, evidence-based way to preserve lean mass during weight loss is the opposite of the video's advice: adequate or higher dietary protein plus resistance training. BCAAs alone are actually inferior to complete protein — they cannot sustain muscle-protein synthesis, because the other essential amino acids needed to build muscle then have to be scavenged from muscle breakdown (Wolfe, J Int Soc Sports Nutr 2017) [Human]. Tellingly, the same video ends up conceding that protein and resistance training matter after all. This page gives no supplement doses or "muscle-preservation protocol"; lean-mass and bone changes on a GLP-1 are something to monitor with a clinician (a baseline DXA, adequate protein, and resistance training are the standard levers), not a reason to swap food protein for a branded amino-acid stack.