Best SARMs for Gaining Weight: What the Clinical Evidence Actually Shows

Key takeaways

What "gaining weight with SARMs" actually means, and what the FDA says

Selective androgen receptor modulators (SARMs) are investigational compounds developed to reproduce testosterone's effects on muscle and bone while limiting action on other androgen-sensitive tissues. Despite being studied in clinical trials, none has been approved by the FDA or the European Medicines Agency for any indication, including weight gain, muscle building, or treatment of muscle wasting.

Searches for the "best" SARM for gaining weight typically conflate two different things: an increase in lean body mass (muscle, generally measured by DEXA scan) and an increase in total body weight, which can include fat and water. Most of the human trials reviewed below measured lean body mass in controlled, short-duration settings in specific patient populations, such as people with cancer cachexia or hip fracture, rather than real-world weight or muscle gain from bodybuilding-style use at unregulated doses.

The FDA has repeatedly warned that products marketed as SARMs are unapproved drugs, not dietary supplements. In a consumer update, the agency stated that it continues to receive adverse event reports and that studies and reports show SARMs are associated with serious or life-threatening health problems, including increased risk of heart attack or stroke, psychosis and hallucinations, sleep disturbances, sexual dysfunction, liver injury and acute liver failure, infertility, pregnancy miscarriage, and testicular shrinkage.

A 2024 pharmacovigilance review of published case reports found that since 2020, 20 reports of adverse events, most described as drug-induced liver injury, had been published in connection with SARM use, with cholestatic or hepatocellular injury and jaundice as the main findings. The same review noted that limited data exist on the actual dosages and purity of the products involved, which complicates any attempt to establish a clear dose-response relationship for harm.

LGD-4033 (Ligandrol): the SARM with the most controlled dosing data in healthy volunteers

LGD-4033 has been studied in a randomized, placebo-controlled trial in healthy young men, generally cited as the Basaria et al. trial published in the Journals of Gerontology. Over a short dosing period, LGD-4033 produced a long elimination half-life and dose-proportional accumulation with multiple dosing, and lean body mass increased in a dose-dependent way, while fat mass did not change significantly. The same trial found dose-dependent suppression of total testosterone, sex hormone-binding globulin, HDL cholesterol, and triglyceride levels, with free testosterone and FSH suppressed only at the higher dose tested. Hormone levels and lipids returned to baseline after the drug was stopped, and the study's authors concluded that LGD-4033 was safe over this short observation period and increased lean body mass without a measured change in prostate-specific antigen.

Separately, the compound (under the developmental name VK5211) was tested by Viking Therapeutics in a phase 2 trial in patients recovering from hip fracture surgery, an indication unrelated to elective bodybuilding, where secondary outcomes reportedly included bone anabolism markers and a 6-minute walk test in addition to lean mass. This program has not led to FDA approval, and its detailed peer-reviewed results are not as readily accessible as the phase 1 data described above.

Case reports outside of the controlled trials tell a different story about real-world use. A published case describes a 32-year-old man hospitalized with jaundice and perisinusoidal fibrosis after taking LGD-4033 at 10 mg per day for two weeks, a dose and duration far outside anything studied in the phase 1 trial. This illustrates a recurring pattern in the SARM literature: the controlled trial doses that produced lean-mass gains without obvious short-term harm are far lower than the doses reported in liver injury case series linked to unsupervised use.

Ostarine (MK-2866 / enobosarm): the largest human trial program among SARMs, but one that ultimately failed to win approval

Ostarine (also called enobosarm or GTx-024) has the most extensive publicly documented human clinical trial history of any SARM. In a phase 2 trial in 159 patients with cancer-induced muscle loss (cancer cachexia), participants received placebo, 1 mg, or 3 mg of ostarine daily for 16 weeks; the trial met its primary endpoint of increased total lean body mass and its secondary endpoint of improved muscle performance measured by stair climb, compared with placebo.

A separate phase 2 trial in healthy elderly men and postmenopausal women found that oral enobosarm significantly increased total lean body mass and improved physical function over 12 weeks compared with placebo.

Despite these phase 2 results, ostarine's phase 3 program in cancer cachexia did not succeed. According to reporting on the trial outcomes, ostarine was unsuccessful in treating cachexia in cancer patients because improvements in muscular strength were not significant, despite continued increases in muscle mass on imaging, and the sponsor ceased pursuing that specific indication. This distinction between lean-mass gain and functional or strength improvement is central to interpreting all SARM trial data, since a DEXA-measured increase in tissue mass does not automatically translate into a clinically meaningful improvement in strength or function.

No trial has evaluated ostarine's effects on weight or muscle gain in healthy, non-wasting adults using it for bodybuilding purposes at the doses and durations typical of unsupervised use.

RAD140 (Testolone): no published human data on weight or muscle gain in any population

RAD140 is frequently marketed online as a muscle-building SARM, but its human testing has been confined to a phase 1 dose-escalation trial in postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer, not in healthy adults or bodybuilders. The trial's primary objective was to establish safety, tolerability, and the maximum tolerated dose, which was set at 100 mg once daily; it did not measure lean body mass or weight as an outcome. The most common adverse events reported in that trial were elevated liver enzymes (AST and ALT), decreased appetite, and constipation, and an independent summary of the early-phase data describes grade 3/4 adverse events occurring in up to roughly three-quarters of patients, though these were reported as reversible with no treatment-related deaths.

Separately, clinical case reports have linked RAD140 use to idiosyncratic drug-induced liver injury, with authors cautioning that if this cause is missed in a young or middle-aged patient with new liver injury and use continues, it can plausibly progress toward fulminant liver failure or decompensated cirrhosis.

There is, in short, no published controlled human trial demonstrating that RAD140 increases lean body mass or body weight in any population, healthy or otherwise. Claims about its muscle-building effectiveness in humans rest on preclinical (animal) data, mechanism-of-action reasoning, and anecdotal reports, not on the kind of DEXA-verified human outcome data that exists for LGD-4033 or ostarine.

MK-677 (Ibutamoren): commonly sold alongside SARMs but not a SARM

MK-677 (ibutamoren) is routinely marketed and discussed alongside SARMs, including in "bulking stacks," but it works through an entirely different mechanism. It is a growth hormone secretagogue and ghrelin receptor agonist that stimulates the pituitary gland to release more growth hormone and raises IGF-1 levels; it does not bind the androgen receptor and is not classified as a SARM pharmacologically.

Like SARMs, MK-677 is not approved by the FDA for human use. It is not legal as an ingredient in dietary supplements, and it can only be legally obtained for research purposes; the FDA has issued warning letters over its illegal sale, including one instance in which it was found as an undeclared ingredient in a children's growth supplement. Anti-doping authorities classify it separately from SARMs, placing it in the growth hormone releasing factors category on the WADA Prohibited List rather than the SARM category, and it is prohibited at all times in Olympic sport.

Because MK-677 stimulates ghrelin signaling, its most consistently reported effect in the available literature is a marked increase in appetite, which is part of why it is marketed for weight gain; it also raises growth hormone and IGF-1 levels. Any discussion of MK-677 as a weight-gain aid should not be conflated with the androgen-receptor-mediated lean-mass data reviewed above for actual SARMs, since the mechanism, the hormonal effects, and the risk profile (including concerns about blood glucose and insulin sensitivity raised in the secondary literature) are different from those of LGD-4033, ostarine, or RAD140.

Products sold online do not reliably contain what the label says

Independent laboratory analyses of products marketed online as SARMs have repeatedly found a mismatch between labeled and actual contents. In a JAMA-published investigation, researchers analyzed 44 products purchased online that were marketed as SARMs; only a little more than half of the products that claimed to contain SARMs such as ostarine, LGD-4033, or andarine actually contained them, and the study's authors concluded that many products sold over the internet as SARMs contained unapproved drugs and substances and were frequently mislabeled.

A later analysis of supplements available to UK consumers using high-resolution mass spectrometry found discrepancies ranging from a product with no detectable active ingredients to products containing undeclared prohibited substances, and even where a labeled SARM was detected, the measured concentration frequently did not match the amount stated on the packaging.

A separate case series examining products listed in a national supplement ingredient database as containing novel ingredients similarly raised concerns about label accuracy across this category of products. Taken together, this body of testing means that a person taking a product bought online cannot assume the dose, or in some cases even the identity, of what they are consuming, which adds an additional layer of unquantifiable risk on top of the pharmacological risks of the compounds themselves.

The bottom line on the clinical evidence

Among the four compounds most often discussed under this search, only ostarine and LGD-4033 have controlled human trial data showing statistically significant increases in lean body mass, and both bodies of evidence come from short trials (12 to 16 weeks) in specific patient populations, such as people with cancer cachexia, hip fracture, or age-related muscle loss, rather than healthy adults deliberately trying to gain weight or muscle. Ostarine's program is the largest and progressed furthest, into phase 3, but that phase 3 program did not succeed on functional outcomes and did not lead to approval. RAD140 has no published human data on weight or lean mass at all; its only human trials are safety studies in breast cancer patients. MK-677 is not a SARM and works through a different hormonal pathway centered on appetite and growth hormone rather than the androgen receptor.

None of this constitutes evidence that any of these compounds is safe or effective for elective weight or muscle gain in healthy people at the doses, durations, or combinations in which they are typically used outside of research settings. The liver injury, cardiovascular, and hormonal signals documented in case reports and pharmacovigilance reviews, combined with well-documented problems with product purity and labeling, mean that anyone considering these substances is doing so without the safety net of FDA review, and largely without reliable knowledge of what is actually in the product they have purchased.

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