peptides for weight loss

the glp-1 class did the work. everything else on the weight-loss shelf rides its coattails.

four molecules moved the obesity needle in the last decade and they are all on the glp-1 receptor: semaglutide, tirzepatide, retatrutide, liraglutide. the rest of the weight-loss peptide shelf is either a different drug class wearing fat-loss marketing or a failed phase-2 compound that stayed on the gray market anyway.

the glp-1 class.

approved benchmarks and late-stage challengers. the cleanest evidence shelf in weight-loss peptides.

tirzepatide (tier S) — dual gip/glp-1 agonist. 22.5% body weight loss at top dose. SURMOUNT-1, NEJM 2022.
retatrutide (tier S) — triple gip/glp-1/glucagon agonist. 24.2% at 48 weeks in phase 2, then 28.3% at 80 weeks in TRIUMPH-1 phase 3. not approved.
semaglutide (tier S) — glp-1 agonist. 14.9% body weight in STEP 1 (NEJM 2021). 20% MACE reduction in SELECT (NEJM 2023).
liraglutide (tier S) — first daily glp-1, fda-approved as saxenda for obesity. ~8% mean weight loss in pivotal trials.
cagrisema (tier B) — novo's semaglutide + cagrilintide combo. missed non-inferiority vs tirzepatide in REDEFINE-4, february 2026.
orforglipron (tier S) — the first non-peptide oral glp-1. ~12.4% body weight at the top dose in ATTAIN-1. fda-approved as foundayo, april 2026.
survodutide (tier A) — glp-1 / glucagon dual agonist (boehringer / zealand). ~16.6% body weight at 76 weeks in SYNCHRONIZE-1; fda breakthrough therapy for MASH.
mazdutide (tier A) — glp-1 / glucagon dual agonist (innovent / lilly). ~14% at 6 mg in GLORY-1, ~20% at 9 mg in GLORY-2. approved in china.
cagrilintide (tier B) — novo's long-acting amylin analog. 11.8% body weight at 68 weeks as monotherapy in the phase-3 REDEFINE-1 trial.

same name-recognition, different evidence questions.

the messy half of the category. some are s-tier drugs by the sitewide evidence ranking, just not obesity drugs. some are failed fat-loss bets. some are research compounds the market talks about as if the human data already exists.

tesamorelin (tier S) — ghrh analog approved (egrifta, fda 2010) for hiv-associated visceral lipodystrophy.
hgh (tier S) — recombinant human growth hormone, fda-approved 1985 for pediatric gh deficiency. multiple adult indications since.
sermorelin (tier A) — ghrh(1-29) analog that stimulates endogenous gh release. fda-approved 1997 for pediatric gh deficiency, voluntarily withdrawn from us market by serono 2008.
mots-c (tier B) — 16-amino-acid peptide encoded inside the mitochondrial 12S rRNA. discovered by Lee et al, Cell Metab 2015.
hgh frag 176-191 (tier C) — lipolytic c-terminal fragment of hgh.
aod-9604 (tier D) — the hgh 176-191 fragment with tyrosine added for stability.
5-amino-1mq (tier D) — small-molecule NNMT inhibitor. ~7% body weight reduction in obese mice over 11 days. zero published human trials.

specific-question reference.

which peptide has the largest published weight-loss effect size?

retatrutide has the largest published investigational signal: 24.2% in phase 2 at 48 weeks, then 28.3% in TRIUMPH-1 phase 3 at 80 weeks. it is not approved. among approved drugs, tirzepatide leads with 22.5% body weight loss at 72 weeks at top dose in SURMOUNT-1. semaglutide hit 14.9% in STEP 1.

is there an oral fda-approved option for weight loss?

yes. orforglipron (foundayo). the first oral small-molecule glp-1 receptor agonist approved for chronic weight management, april 2026. not a peptide. solves the no-needles question telehealth has been begging for.

what does the trial data show about peptides and visceral fat?

tirzepatide and semaglutide trials report visceral adipose reduction alongside total weight loss. tesamorelin is fda-approved specifically for hiv-associated visceral lipodystrophy, the cleanest visceral-fat-specific indication in the category. hgh has body-composition biology and approved endocrine indications, but it is not an obesity drug. those are separate evidence buckets.

what's in the trial record for body recomposition?

the gh-axis literature (cjc-1295, ipamorelin, sermorelin, tesamorelin) reports modest lean-mass and fat-mass shifts in healthy adults. magnitudes are real but smaller than the magnitude of fat loss reported on the glp-1 class. body recomp without weight loss is not a problem these compounds solve at meaningful scale in the trial record.

are there sex-specific differences in the glp-1 weight-loss data?

SURMOUNT (tirzepatide) and STEP (semaglutide) both enrolled men and women, both reported broadly similar mean outcomes across sexes. the published record does not turn that into a one-size-fits-all dosing story.

how does the gray-market research-peptide evidence compare to the fda-approved evidence?

different evidence categories. fda-approved peptides have multi-thousand-patient phase-3 rcts. research-chemical compounds (5-amino-1mq, hgh frag 176-191, peptide-vendor stack literature) have rodent studies and uncontrolled user reports. treating one as if it were the other is the most common mistake in this space.

what the safety literature says.

what gi side effects show up in the glp-1 record?

nausea (~40% at initiation), vomiting (15-25%), constipation, diarrhea. usually transient over the first 4-8 weeks, dose-dependent. all on the fda labels as common adverse events. not surprises.

what does the trial record say about lean-mass loss on glp-1s?

approximately 25-40% of total mass lost is lean tissue. similar to what diet-only weight-loss trials report. ongoing research is examining the role of resistance training and protein intake during treatment.

what does the long-term safety data show for glp-1s?

20+ years of post-marketing data across the class. exenatide approved 2005. published risks: rare pancreatitis, gallbladder events, contraindication for personal or family history of medullary thyroid carcinoma or men2. SELECT (NEJM 2023) reported net cardiovascular benefit. fda surveillance ongoing for muscle/bone density and suicidal ideation. the 2024 fda review found no causal link with semaglutide.

what about the non-glp-1 peptides used in weight-loss contexts?

varies by compound. hgh, tesamorelin, and sermorelin have real medical records in specific indications. aod-9604 has fda gras status as a food additive, not drug approval. mots-c and 5-amino-1mq sit much closer to research-compound territory. absence of published harm signals is not evidence of safety.

claim checks

related comparisons

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.