Body composition
Does it build muscle, or just stop you losing it?
Two different claims that get sold as one. Keeping lean mass during weight loss and adding lean mass to a healthy person are measured in different trials with different results.
1,182
people in trials
28
human studies
7
compounds, animal or cell only
13
trials found nothing
Measured in people
Ranked by how many people, which is a fact about the evidence and not a judgement about the compound. The one at the top is the most studied, which is not the same as the best. Counts are never added across compounds, because the same person can appear in more than one trial.
- 233 people2 human studies1 found nothing
found nothingThe pharmaceutical-grade version of this molecule in 233 older adults with sarcopenia. The primary endpoint, gait speed on a 400-metre walk, improved 0.07 m/s against placebo in the full analysis set and was not significant, and improved 0.09 m/s in the per-protocol population at p = 0.008. Detail on the BIO101 page.
Journal of Cachexia, Sarcopenia and Muscle, 2025 · 233 people
A controlled clinical trial in humans. Significantly higher increases in muscle mass in participants dosed with ecdysterone, and significantly more pronounced increases in one-repetition bench press performance. The same hypertrophic effect appeared in C2C12 myotubes in vitro. No increase in liver or kidney toxicity biomarkers. Participants were screened for prohibited performance-enhancing substances and the supplement was tested for anabolic steroid contamination before administration. The authors conclude their results strongly suggest including ecdysterone on the prohibited list in class S1.2, other anabolic agents.
Archives of Toxicology, 2019 · no headcount in the line
- 201 people1 human study1 found nothing
found nothing201 older adults randomised, 99 to placebo and 102 to the antibody, from 365 screened. At 24 weeks appendicular lean body mass changed by minus 0.123 kg on placebo and plus 0.303 kg on drug, a difference of 0.43 kg (95% CI 0.192 to 0.660, p < 0.0001). On function: twelve-step stair climb minus 1.28 s (p = 0.011), four-step stair climb minus 0.46 s (p = 0.093), chair rise with arms minus 4.15 s (p = 0.054), fast gait speed plus 0.05 m/s (p = 0.088), tested against a prespecified two-sided alpha of 0.1 for performance tests. No effect on other performance measures. Injection site reactions in 30% on drug against 9% on placebo (p < 0.0001). Funded by Eli Lilly.
Lancet Diabetes and Endocrinology, 2015 · 201 people
- 159 people1 human study1 found nothing
found nothing159 patients with cancer and at least 2% weight loss, randomised to enobosarm 1 mg, 3 mg or placebo for up to 113 days. Total lean body mass rose significantly on both doses (median 1.5 kg on 1 mg, 1.0 kg on 3 mg) while placebo did not change. This is the Phase 2 trial that preceded the POWER Phase 3 program.
The Lancet Oncology, 2013 · 159 people
- 94 people1 human study
94 adults aged 65 and over did 14 weeks of supervised resistance training on 1,700 mg/day metformin or placebo. Placebo gained more lean body mass (p = .003) and thigh muscle mass (p < .001), with greater gains in thigh muscle area (p = .005) and density (p = .020), plus a trend toward blunted strength gains.
Aging Cell, 2019 · 94 people
- 76 people1 human study
The long-term efficacy and safety experience behind the approval. 76 children with IGF-1 deficiency due to growth hormone insensitivity treated with recombinant human IGF-1 for up to 12 years under a predominantly open-label design, at 60 to 120 micrograms per kilogram subcutaneously twice daily. Height velocity rose from a mean of 2.8 cm per year at baseline to 8.0 cm per year in the first year (p less than 0.0001) and was dose dependent; velocities were lower in subsequent years but stayed above baseline for up to 8 years. The most common adverse event was hypoglycaemia, reported by 49 percent of treated subjects and observed both before and during therapy, followed by injection site lipohypertrophy (32 percent) and tonsillar or adenoidal hypertrophy (22 percent). Note the design: predominantly open label, not randomised against placebo.
Journal of Clinical Endocrinology and Metabolism, 2007 · 76 people
- 65 people1 human study1 found nothing
found nothing65 adults aged 60 to 81 on MK-677 25 mg daily for up to 2 years: GH and IGF-1 rose to young-adult levels and fat-free mass increased 1.1 kg vs a 0.5 kg loss on placebo, but strength and function did not improve and fasting glucose and insulin resistance rose.
Annals of Internal Medicine, 2008 · 65 people
- 65 people1 human study
65 healthy adults aged 60 to 81 took MK-677 25 mg orally once daily or placebo for two years in a double-blind randomised modified-crossover trial. Growth hormone and IGF-1 rose into the healthy young adult range without serious adverse events. Fat-free mass increased 1.1 kg on MK-677 against a 0.5 kg fall on placebo, and body cell mass measured as intracellular water rose 0.8 kg against a 1.0 kg fall. This is the longest randomised trial of any secretagogue in this database.
Annals of Internal Medicine, 2008 · 65 people
- 53 people2 human studies1 found nothing
30 men with BMI at or above 26, randomised double-blind to 250 mg of a 10 percent forskolin extract twice daily or placebo for 12 weeks. Body fat percentage and fat mass on DXA fell significantly against placebo, bone mass changed significantly, serum free testosterone rose significantly, and lean body mass showed a non-significant trend upward (p equals 0.097). Fifteen participants per arm.
Obesity Research, 2005 · 30 people
found nothing23 women randomised double-blind to 250 mg of a 10 percent Coleus forskohlii extract twice daily (n equals 7) or placebo (n equals 12) for 12 weeks. No significant differences in fat mass, fat-free mass or body fat percentage. Non-significant trends toward mitigating gains in body mass (p equals 0.10) and scanned mass (p equals 0.08). Treated participants reported less hunger and fullness. No clinically significant changes in blood lipids, liver or muscle enzymes, thyroid hormones, insulin, heart rate or blood pressure. The authors concluded it does not appear to promote weight loss but may help mitigate weight gain.
Journal of the International Society of Sports Nutrition, 2005 · 23 people
- 50 people2 human studies1 found nothing
found nothingSARA-INT. 233 randomised, mean age 75.5, 54.3% female, three arms at 175 mg twice daily, 350 mg twice daily or placebo, planned six months and up to nine in 50 subjects. Eligibility required meeting FNIH sarcopenia criteria and a Short Physical Performance Battery score of 8 or less out of 12. Primary endpoint was change in gait speed on the 400-metre walk test. At 350 mg twice daily, gait speed improved 0.07 m/s against placebo in the full analysis set, not significant, and 0.09 m/s in the per-protocol population, p = 0.008. COVID-19 cost 55% of on-site end-of-treatment efficacy assessments, reducing power. Predefined higher-risk subpopulations showed effects of 0.047 to 0.066 m/s with a trend toward dose response. Safety was good, with related treatment-emergent adverse events in 16.0%, 13.3% and 13.5% of the placebo, 175 mg and 350 mg groups. Many authors are employees, former employees, advisory board members or consultants of the sponsor, Biophytis.
Journal of Cachexia, Sarcopenia and Muscle, 2025 · 50 people
The same molecule in a sports context, where a controlled human trial found increased muscle mass and bench press performance. Included because the contrast between a positive strength result in trained young people and a missed functional endpoint in sarcopenic older adults is the central fact about this compound.
Archives of Toxicology, 2019 · no headcount in the line
- 50 people1 human study
The entire published obesity efficacy record: 50 participants across five dose cohorts and placebo, mean baseline weight 92.9 kg. Mean weight reduction was 7.16 percent against 0.86 percent on placebo, and 82.5 percent of treated participants lost at least 5 percent against none on placebo. Fat mass fell 4.47 kg and lean mass also fell 2.00 kg. This is a 50 person dose-ranging study, not an obesity efficacy trial, and the compound is not approved for weight management.
Diabetes, Obesity and Metabolism, 2026 · 50 people
- 48 people2 human studies
One dose in 48 postmenopausal women: half-life 10 to 15 days; at 3 mg/kg total lean mass rose 3.3% and thigh muscle volume 5.1% by day 29.
Muscle and Nerve, 2013 · 48 people
The trial was stopped after the second dose level because of epistaxis and telangiectasias; only non-significant trends toward preserved six-minute walk and higher lean mass were seen.
Muscle and Nerve, 2017 · no headcount in the line
- 30 people1 human study1 found nothing
found nothing30 healthy men, mean age 71, randomised to 2.5 g leucine or placebo with each main meal, 7.5 g daily for three months. No change in skeletal muscle mass measured by computed tomography and DXA, and no change in one-repetition-maximum strength, in either group. No improvement in whole-body insulin sensitivity, HbA1c or plasma lipids.
American Journal of Clinical Nutrition, 2009 · 30 people
- 24 people1 human study1 found nothing
found nothingSix months of rhGH in 24 GH-deficient adults raised lean mass by 5.5 kg and cut fat mass by 5.7 kg versus placebo, with no change in body weight.
New England Journal of Medicine, 1989 · 24 people
- 18 people2 human studies2 found nothing
found nothingThe first randomised controlled trial. 11 healthy men aged 18 to 40, two 2-week cycles of oral clenbuterol at 80 micrograms a day versus placebo with a 3-week washout. Lean mass +0.91 kg (95% CI 0.02 to 1.81, p < 0.05), no effect on fat mass, maximal oxygen uptake -7% (p < 0.001), exercise capacity -4% (p < 0.001), no change in left ventricular mass, blood volume or haemoglobin mass. Muscle protein content rose while 3-hydroxyacyl CoA dehydrogenase activity and OXPHOS complex V fell. The beta-2 signalling response declined across the 2 weeks.
The Journal of Physiology, 2025 · 11 people
found nothing7 heart failure patients on a left ventricular assist device given oral clenbuterol up-titrated to 720 micrograms a day for 3 months. No serious adverse events or arrhythmias, creatine phosphokinase rose in 4 patients. Ejection fraction did not improve and end-diastolic dimension increased; body weight and lean mass rose and quadriceps maximal voluntary contraction improved from 37.0 to 45.8 kg. Cardiac function did not improve.
The Journal of Heart and Lung Transplantation, 2006 · 7 people
- 16 people1 human study1 found nothing
found nothing16 healthy men, mean age 29, randomised to eight weeks of resistance training alone (n equals 7) or with ursolic acid (n equals 9), one capsule three times daily. Body fat percentage fell significantly in the supplemented group (p less than 0.001) while body weight, body mass index, lean body mass, glucose and insulin were unchanged. IGF-1 and irisin rose from baseline in the supplemented group, as did several maximal extension and flexion measures.
Korean Journal of Physiology and Pharmacology, 2014 · 16 people
- no headcount stated2 human studies1 found nothing
found nothingA pure anti-myostatin antibody against placebo. The difference in four-stair climb time at week 49 was 0.27 seconds, 95% CI minus 7.4 to 7.9, p = 0.94. No secondary clinical endpoint separated and muscle volume gains were not significant.
Neuromuscular Disorders, 2020 · no headcount in the line
Receptor-level blockade rather than myostatin-only blockade, so it neutralises activin A too. At 48 weeks fat mass fell 20.5% (7.5 kg) against 0.5% on placebo, lean mass rose 3.6% (1.7 kg), waist fell 9.0 cm and HbA1c fell 0.76 points, all p < 0.006.
JAMA Network Open, 2021 · no headcount in the line
- no headcount stated1 human study
48 weeks of low-dose intermittent rapamycin was relatively safe in normative-aging adults; lean mass and pain improved in women on 10 mg.
Aging, 2025 · no headcount in the line
- no headcount stated1 human study
Preserved 54.9% of lean mass on tirzepatide; weight lost was 85% fat.
Scholar Rock press release, 2025 · no headcount in the line
- no headcount stated1 human study
Triple regimen preserved 80.9% of lean mass with 27.3% more fat loss.
Regeneron press release, 2025 · no headcount in the line
- no headcount stated1 human study
The head to head the skin literature never runs. Against an equal protein dose, collagen did not stimulate muscle protein synthesis where whey did, including when leucine was matched.
American Journal of Clinical Nutrition, 2020 · no headcount in the line
- no headcount stated1 human study
The human trial turkesterone's reputation is borrowed from, and it tested a different molecule. Ecdysterone increased muscle mass and one-repetition bench press performance in a controlled human trial. Nothing in it concerns turkesterone.
Archives of Toxicology, 2019 · no headcount in the line
- no headcount stated1 human study1 found nothing
found nothing120 ambulatory boys aged 6 to under 16 with Duchenne muscular dystrophy, 80 on domagrozumab at 5, 20 and 40 mg/kg and 40 on placebo, two 48-week periods. Primary endpoints were safety and change in four-stair climb time at week 49. The difference in mean change was 0.27 seconds (95% CI minus 7.4 to 7.9), p = 0.94. There were no significant between-group differences in any secondary clinical endpoint. Non-significant increases in muscle volume were observed. An erratum was published in 2021.
Neuromuscular Disorders, 2020 · no headcount in the line
Measured in animals or cells, not yet in people
These are separated from the trials above rather than ranked against them, because they answer a different question. A result in a rat is a real result and a reason somebody ran the study; it is not a measurement of what happens in you. Where the human work is missing, the reason is usually money rather than failure, and that is set out at the bottom of this page.
- 1 preclinical study
Measured in animals or cells
Muscle-restricted IGF-1 expression in mice produced persistent hypertrophy and preserved regenerative capacity into old age, the mechanistic basis for IGF-1 muscle research.
Nature Genetics, 2001 · animal
- 1 preclinical study
Measured in animals or cells
Follistatin blocks myostatin binding to ActRIIB; transgenic mice overexpressing follistatin in muscle showed dramatic increases in muscle mass.
Proceedings of the National Academy of Sciences, 2001 · animal
- 1 preclinical study
Measured in animals or cells
Better muscle function in old mice; 17.9% lifespan extension in C. elegans; low levels in human sarcopenia.
Nature Metabolism, 2024 · animal
- 1 preclinical study
Measured in animals or cells
Mouse, heterochronic parabiosis. The original claim: GDF11 declines with age and restoring it reversed age-related cardiac hypertrophy. This is the paper the young blood narrative rests on.
Cell, 2013 · animal
- 1 preclinical study
Measured in animals or cells
Each drug alone, started at 4 or 16 months, improved rotarod and endurance and reduced cardiac hypertrophy in aged UM-HET3 mice of both sexes; acarbose changed the cardiac lipidome more than rapamycin; some benefits male-only. Healthspan measures for the single drugs, not the combination.
- 1 preclinical study
Measured in animals or cells
A new osteocalcin-deficient mouse made by deleting Bglap and Bglap2. Bone quantity, glucose metabolism, testosterone synthesis and muscle mass were all normal. What was abnormal was the crystallographic orientation of bone apatite, and bone strength fell as a result. The authors conclude osteocalcin does not function as a hormone.
PLoS Genetics, 2020 · animal
- 1 preclinical study
Measured in animals or cells
C2C12 myotubes treated with 15 micromolar urolithin B for 24 hours grew and differentiated more, through increased protein synthesis and repression of the ubiquitin-proteasome pathway, with the androgen receptor implicated. In mice, 10 micrograms a day delivered continuously by implanted mini-osmotic pump for 28 days induced muscle hypertrophy and reduced atrophy after sciatic nerve section. Cells and mice, by continuous infusion, not an oral human dose.
Why the trial record looks like this
A missing trial is usually a missing sponsor. Nobody runs a nine-figure programme on a molecule they cannot own, so the compounds with the thinnest human records are often the oldest and most freely available ones rather than the weakest. Taking GDF11 as the example, because it states the problem most clearly:
GDF11 is the clearest antibody-specificity cautionary tale in ageing biology, and it is worth understanding as a general lesson rather than a fact about one molecule. GDF11 and myostatin differ by eleven amino acids in the part that does the signalling. If your reagent cannot tell them apart, then a measured decline in one can be a decline in the other, and a rejuvenation result can be a story about the wrong protein.
That is not a hypothetical here. The rebuttal paper states plainly that the reagents used in the original work were not GDF11-specific, and the group that built a specificity-controlled mass spectrometry assay found the age relationship running the other way in humans.
Where the field actually stands is more interesting than either camp's headline. Exogenous GDF11 does appear to improve physiology in several animal disease models, including cardiac fibrosis and experimental stroke. So the molecule may well do something useful. What has not survived is the specific claim that made it famous: that GDF11 falls with age and topping it back up rejuvenates. Anything sold to you on that premise is being sold on a 2013 paper and a decade of contradiction.
A compound appears here only when a citation on its own page states this outcome and reports a result for it; naming it is not enough. Human, animal and cell work are counted separately and never merged. Participant counts are read from the study lines and deliberately undercount. Nothing here is advice, and nothing here is a recommendation to take or to avoid anything.