Peptides vs steroids, SARMs and HGH
Four kinds of compound often sold side by side for muscle and recovery: what each one is, where it acts, what human studies found, and where each stands in the US and in sport.
At a glance
| Kind | What it is | How it works | US status | Sport (WADA 2026) |
|---|---|---|---|---|
| Peptides | Chains of up to 40 amino acids; longer chains count as proteins under FDA’s definition. | Mostly as signals on receptors. Those sold for muscle, such as ipamorelin, CJC-1295 and sermorelin, make the pituitary release more of the body’s own growth hormone. | Some are approved drugs, such as semaglutide. Most sold online are unapproved and labeled for research. | Growth hormone releasers, GH fragments, IGF-1 and TB-500 are banned at all times (S2); other unapproved drugs fall under S0. |
| HGH (somatropin)Compound page | Growth hormone itself: a 191-amino-acid protein made with recombinant DNA. | Acts on growth hormone receptors directly and raises IGF-1. | Prescription only, for growth hormone deficiency and certain growth disorders. Distributing it for any other use is a federal crime, with up to 5 years in prison. | Banned at all times (S2.2.3). |
| Anabolic steroids | Synthetic relatives of testosterone, built on a steroid ring. | Act on the androgen receptor, the one testosterone uses. | Schedule III controlled substances. Possessing them without a valid prescription is a federal crime. | Banned at all times (S1.1). |
| SARMs | Nonsteroidal small molecules, such as enobosarm (ostarine), LGD-4033 (ligandrol) and RAD140. | Act on the androgen receptor, designed to favor muscle and bone over other tissues. | None is FDA-approved. FDA says products containing them aren’t dietary supplements, though they’re often sold as supplements or for research. | Banned at all times (S1.2). |
| MK-677 (ibutamoren)Compound page | A small molecule taken by mouth. It isn’t a peptide or a SARM. | Acts on the ghrelin receptor, like the GHRP peptides, to release growth hormone. | Not approved anywhere; still in trials. | Banned at all times (S2.2.4). |
Where each one acts
Two hormone systems, simplified. Muscle-building compounds either add a hormone or push the body to make more of its own.
The growth hormone axis
- The brain (hypothalamus) sends GHRH to the pituitaryGHRH analogs copy this signal: sermorelin, tesamorelin, CJC-1295 (no DAC)
- Ghrelin, a stomach hormone, adds a second push through its own receptorGhrelin mimetics copy it: ipamorelin, GHRP-2, GHRP-6, hexarelin and the pill MK-677
- The pituitary releases growth hormone in pulsesHGH replaces this step: it is growth hormone
- The liver answers with IGF-1IGF-1 and its analogs skip ahead to this step: IGF-1 LR3, IGF-1 DES and the approved drug mecasermin
- Muscle, bone, fat and other tissues respond
The androgen receptor
- The brain sends GnRH to the pituitaryGonadorelin is GnRH; kisspeptin-10 triggers its release
- The pituitary releases LH and FSHhCG acts like LH
- The testes make testosterone; in women, the ovaries and adrenal glands make smaller amountsAnabolic steroids add testosterone or synthetic versions of it
- Androgen receptors in muscle, bone, skin and the prostate respondSARMs act here too, designed to favor muscle and bone
- High androgen levels tell the brain to cut GnRH and LH, so the body’s own testosterone and sperm production fallThis is why steroids can shrink the testicles and cause infertility, and why LGD-4033, a SARM, lowered testosterone in a trial
Our drawing. Linked names have their own pages here, including HGH (somatropin) and mecasermin; steroids and SARMs aren’t in the library.
What human studies found
Different people, doses and lengths, so the numbers can’t be compared head to head. No trial has tested these groups against each other.
| Compound | Study | What happened |
|---|---|---|
| Testosterone, high dose | 43 healthy men, 600 mg a week for 10 weeks, randomized against placebo (1996) | With weight training, fat-free mass rose 6.1 kg and bench press 22 kg on average. Without training, muscle size and strength still rose more than on placebo. |
| HGH in fit young adults | Review of 27 trial groups, 303 people given GH, mostly for days to weeks (2008) | Lean mass rose 2.1 kg more than without GH, but strength and exercise capacity didn’t improve. Swelling and fatigue were more common. |
| HGH in healthy older adults | Review of 18 trials, 220 people given GH for about 27 weeks on average (2007) | Lean mass rose 2.1 kg and fat fell 2.1 kg. Swelling, joint pain, carpal tunnel syndrome and breast growth in men were more common, and diabetes or prediabetes somewhat more so. |
| Enobosarm, a SARM | 120 older men and women past menopause, 12 weeks, randomized against placebo (2011) | At 3 mg, lean mass rose 1.3 kg more than on placebo and stair-climb function improved; HDL cholesterol fell about 15 mg/dL. |
| LGD-4033, a SARM | 76 healthy young men, 21 days, randomized against placebo (2013) | Lean mass rose with the dose. Total testosterone and HDL cholesterol fell, and both recovered after stopping. |
| MK-677 | 65 healthy adults aged 60 to 81, 12 months, randomized against placebo (2008) | Lean mass rose 1.1 kg vs a 0.5 kg loss on placebo, with no gain in strength or function; fasting blood sugar rose. |
| Hexarelin and sermorelin | 12 healthy older adults for 16 weeks; 11 healthy older men for 6 weeks, without a placebo group | Neither changed lean mass. Ipamorelin and CJC-1295 have never been tested for muscle in people. |
| Tesamorelin | Two 26-week trials in adults with HIV and excess belly fat | Lean mass rose 1.2 to 1.3 kg. It’s approved only to reduce belly fat in people with HIV, not to build muscle. |
Side effects compared
- Anabolic steroids. Testosterone’s label lists, with misuse, heart attack, heart failure, stroke, liver damage, depression, aggression and psychosis; in men, shrunken testicles and infertility; in women, a deeper voice, body hair and menstrual changes. Stopping high doses can bring depression, fatigue and low sex drive for weeks or months.
- SARMs. FDA lists liver injury, including acute liver failure, a higher risk of heart attack and stroke, psychosis, infertility and testicular shrinkage. In trials they lowered HDL cholesterol and testosterone.
- HGH. Swelling, joint pain, numb or tingling hands (carpal tunnel syndrome) and higher blood sugar. In adults on Genotropin, most side effects came from fluid retention.
- Growth hormone releasers, including MK-677. Higher blood sugar, fluid retention and joint pain, as with growth hormone itself. In a hip-fracture trial, heart failure in 4 of 62 people on MK-677, vs 1 of 61 on placebo, stopped the trial early.
- Other peptides. It depends on the class: see the side-effect finder and Are peptides safe?
Names that mislead
Online sellers have labeled tirzepatide “GLP-2” and retatrutide “GLP-3,” names FDA quoted in warning letters in March 2026. GLP-2 is a different gut hormone, copied by teduglutide (Gattex) to treat short bowel syndrome, and Lilly, which is developing retatrutide, calls “GLP-3” scientifically inaccurate. Tirzepatide acts on GIP and GLP-1 receptors; retatrutide adds the glucagon receptor.
Not growth hormone: a 16-amino-acid piece of it, and vials sold under the name often list AOD9604’s sequence instead. WADA bans GH fragments along with GH itself. See HGH Fragment 176-191.
It’s neither: a small molecule that acts on the ghrelin receptor. Tested products sold as SARMs have contained it.
The label doesn’t change what a product is or how it’s regulated. FDA has rejected the disclaimer where a seller’s website showed the products were meant for people.
Sources: WADA 2026 Prohibited List (S1 and S2); DEA, Anabolic steroids drug fact sheet (October 2025); 21 U.S.C. 333(e) and 844; 21 CFR 600.3; Genotropin prescribing information (2026); Depo-Testosterone prescribing information, section 9; FDA, Certain bodybuilding products put consumers at risk (December 2025); FDA warning letters to online sellers (March 31, 2026); Eli Lilly, What to know about retatrutide (September 2026); Gattex prescribing information; Bhasin et al., NEJM 1996, PMID 8637535; Liu et al., Ann Intern Med 2007, PMID 17227934, and 2008, PMID 18347346; Dalton et al., J Cachexia Sarcopenia Muscle 2011, PMID 22031847; Basaria et al., J Gerontol A 2013, PMID 22459616; Nass et al., Ann Intern Med 2008, PMID 18981485; Adunsky et al., Arch Gerontol Geriatr 2011, PMID 21067829; Rahim et al., J Clin Endocrinol Metab 1998, PMID 9589671; Vittone et al., Metabolism 1997, PMID 9005976; Falutz et al., N Engl J Med 2007, PMID 18057338, and J Clin Endocrinol Metab 2010, PMID 20554713; Van Wagoner et al., JAMA 2017, PMID 29183075.