Peptides vs. Traditional Anabolics: Comparing the Evidence

Why the comparison is lopsided

Lifters often ask whether peptides are "better" than steroids. The answer depends on the goal, but the question hides a bigger problem: the two sides don't have the same kind of evidence behind them.

Anabolic-androgenic steroids (AAS) such as testosterone bind the androgen receptor directly, and their effects on muscle have been measured in randomized controlled trials. Growth hormone secretagogues such as ipamorelin and CJC-1295 instead push the pituitary to release more of the body's own growth hormone; MK-677 does the same by mouth, though it's a small molecule rather than a peptide. BPC-157 and TB-500 are studied for tissue repair, almost entirely in animals. AOD-9604 is a growth hormone fragment that was developed as an obesity drug.

Nobody has tested a peptide head-to-head against a steroid in a human trial, so this page compares what each has shown on its own. For the mechanism side of the story, see our comparison of how peptides and anabolic steroids work.

For Raw Mass, There's Still No Contest

On muscle and strength, the human data favor AAS by a wide margin. In a 1996 trial published in the New England Journal of Medicine, 43 healthy men were randomized to weekly injections of 600 mg testosterone enanthate or placebo for 10 weeks, with or without weight training. The men who got testosterone and trained gained 6.1 kg of fat-free mass on average, and their bench press rose by 22 kg. Even the men who took testosterone without training gained more muscle size and strength than the placebo group that didn't train.

That trial dose is far above normal testosterone levels, and real-world use often runs higher: in a 2006 survey of 500 AAS users recruited on steroid message boards, 59.6% reported at least 1,000 mg of testosterone or its equivalent per week.

The closest peptide-side data come from MK-677. In a 2-year randomized trial in 65 healthy adults aged 60 to 81, 25 mg a day by mouth raised growth hormone and IGF-1 into the young-adult range. Fat-free mass rose by 1.1 kg while it fell slightly on placebo, but strength and physical function didn't change. In a Phase IIb trial in older adults recovering from hip fracture, the same dose didn't improve most functional measures, and the trial was stopped early over a congestive heart failure signal.

As of October 2026, the human data for ipamorelin and CJC-1295 are short studies showing that they raise growth hormone and IGF-1; no trial has measured muscle or strength. A 2017 review noted that few long-term, rigorously controlled studies of growth hormone secretagogues exist. Users describe slower and smaller changes than with AAS, which fits the trial data.

Fat loss while preserving muscle

Testosterone has a controlled trial here too. In a 2019 study, 50 young men spent 28 days in a severe energy deficit (55% below their energy needs). Those given 200 mg testosterone enanthate a week gained lean mass while the placebo group held steady, a 2.5 kg difference. Fat loss was the same in both groups. In that trial, testosterone protected lean mass but didn't speed fat loss.

Clenbuterol, an older non-hormonal cutting drug, is a beta-2 agonist that WADA's 2026 Prohibited List classes as an anabolic agent (S1.2). Users commonly describe a racing heart and anxiety with it; we didn't review its trial data for this page.

Growth hormone promotes lipolysis (the breakdown of stored fat), which is the usual reason lifters use secretagogues when cutting. But in the 2-year MK-677 trial, total fat and abdominal visceral fat didn't change, and limb fat went up. Fasting glucose rose by about 5 mg/dL and insulin sensitivity fell. No trial has measured fat loss with ipamorelin or CJC-1295.

AOD-9604 is the peptide most often sold for fat loss, and its human record is negative. FDA's 2024 review for its compounding advisory committee found that most of the sponsor's trials showed no weight-loss benefit over placebo. The largest, the OPTIONS trial, enrolled 536 adults with obesity on oral doses of 0.25, 0.5 or 1 mg daily for 24 weeks; it missed its 12-week weight-loss endpoint, and the sponsor stopped developing the drug for obesity. The sponsor reported no change in IGF-1. FDA called the human safety data limited and found no human data for injected use, which is how users take it. Users on peptide forums mostly report little or no change. As of October 2026, AOD-9604 isn't approved anywhere.

Injury recovery

This is where peptides are most often said to win. The comparison does lean one way, but on different kinds of evidence: AAS have human data linking them to tendon injury, while the recovery peptides have mostly animal data suggesting benefit.

A 2015 cross-sectional study of 142 experienced male bodybuilders found that 22% of long-term AAS users had ruptured at least one tendon, compared with 6% of non-users. It relied on medical histories, so it shows an association rather than proof that AAS caused the ruptures. Many lifters also blame stanozolol (Winstrol) for joint pain; we found no trial that tested this.

BPC-157 has a large animal literature. In a 2006 rat study, for example, it improved healing after the Achilles tendon was cut from the heel bone. Rodent and cell studies link it to angiogenesis (new blood vessel growth). But a 2025 systematic review of BPC-157 in orthopedic sports medicine found that 35 of its 36 included studies were preclinical, and it found no clinical safety data. As of October 2026, the human evidence is three small uncontrolled pilots. TB-500 is a 7-amino-acid fragment of thymosin beta-4; most of the research behind it was done on the full protein, and as of October 2026 FDA says it has found no human exposure data for the fragment.

Users on peptide forums describe both outcomes: some report clear improvement in a stubborn tendon within weeks, while many notice no change after 3-6 weeks. Without a human trial, that gap is hard to interpret; placebo effects and gray-market product quality both play a part (see our guide to peptide sourcing and quality control).

The Real Cost: A Sober Look at Side Effects

The harms of AAS are better documented than those of any peptide on this page. A 2014 Endocrine Society scientific statement linked performance-enhancing drug use to a higher risk of death and to cardiovascular, psychiatric, endocrine, liver and musculoskeletal disorders. The best-known AAS effects include suppression of the body's own testosterone production (which users try to restart afterward with post-cycle therapy), worse cholesterol, higher blood pressure and breast tissue growth from conversion to estrogen. In the 500-user survey, 99.2% reported side effects they attributed to AAS.

The peptides here don't act on the androgen receptor, so testosterone suppression and gynecomastia aren't expected from how they work. That isn't the same as being shown safe:

• MK-677: higher fasting glucose and cortisol, leg swelling, and the heart failure signal that stopped the hip-fracture trial.
• Ipamorelin: FDA cites serious adverse events, including death, when it was given intravenously in a post-surgery trial; causality is unclear.
• CJC-1295: FDA cites increased heart rate and systemic vasodilatory reactions.
• BPC-157, TB-500 and AOD-9604: FDA says it has no, or only limited, human safety information.

So the difference is less "high risk versus low risk" than "known, substantial risk versus risk that hasn't been measured." For what's known about longer use, see our page on long-term health outcomes of peptide use. Some users describe a replacement-level testosterone dose plus peptides as a middle path; no study has tested that combination.

Comparison table

As the last row shows, every compound on this page is banned at all times for tested athletes under WADA's 2026 list; our page on peptide use in competitive sports covers what that means.

What we still don't know

• Head-to-head data. As of October 2026, no human trial has compared any peptide with AAS for muscle, fat loss or recovery.
• Human tendon healing. A University of Arkansas pilot trial (NCT07803250) plans to randomize about 30 people after rotator cuff surgery to daily BPC-157 or placebo injections for 90 days. As of October 2026 it hasn't started recruiting; its listed start date is January 2027.
• Secretagogues in younger lifters. The longest MK-677 data come from adults over 60, and strength didn't change. Nobody has run a comparable trial in younger adults who train.