Short answer: there is no proven best SARM for bulking. No SARM has been tested for muscle gain in healthy, training lifters. The compound with the strongest human lean-mass data is LGD-4033 (ligandrol): 1 mg/day added 1.21 kg of lean mass in 21 days in young men, and it also lowered testosterone and HDL cholesterol at that dose. RAD-140 and YK-11, the two most popular bulking compounds, have no human muscle data at all.
Below we compare the usual bulking compounds on what the studies show, add what users report (clearly labeled as anecdotal), and explain what is and isn’t known about bulking stacks. Every number links back to our SARMs database.
Bulking compounds compared
| Compound | Human muscle evidence | Testosterone suppression | Liver | Half-life | WADA |
|---|---|---|---|---|---|
| LGD-4033 | 2 placebo-controlled trials: +1.21 kg lean mass in 21 days (young men, 1 mg/day); +4.75–9.08% lean mass vs placebo in 12 weeks (older adults after hip fracture) | Yes, at 1 mg/day (total and free testosterone, FSH) | Case reports of cholestatic liver injury | 24–36 h | Banned at all times |
| Ostarine | Several trials: +1.3 kg lean mass vs placebo in 86 days (older adults, 3 mg/day) | Partial (total testosterone, SHBG) | ALT rises in trials; case reports of liver injury | ~14–24 h | Banned at all times |
| RAD-140 | None in humans; muscle effects in rats and monkeys only | Not measured in men; strong in monkeys | Liver-enzyme rises in about half of trial patients; several case reports | ~45 h | Banned at all times |
| YK-11 | None in humans; cell studies only | Not measured; acts on the androgen receptor | Not established | Not established | Banned at all times |
| MK-677 (not a SARM) | +1.1 kg fat-free mass vs −0.5 kg on placebo over 12 months (older adults); strength did not change | Small drop in total testosterone in one trial; LH and FSH unchanged | Reversible ALT/AST rises in a few people | Not published | Banned at all times |
Source: Sarmguide compound database.
The usual bulking picks, one by one
These are the three compounds most often named for bulking. For each one: what the studies show, then what users report. User reports are anecdotal: they can’t tell you how much was from the compound, the diet or the training, or whether the product contained what its label said.
1. Ligandrol (LGD-4033)
What the studies show. In 76 healthy men aged 21–50, LGD-4033 at 0.1, 0.3 or 1.0 mg/day for 21 days raised lean mass with dose, by 1.21 kg on 1.0 mg. Leg-press strength, stair-climbing power and fat mass did not change significantly. Total testosterone, SHBG and HDL fell with dose, and FSH and free testosterone fell on 1.0 mg; all were back to baseline by day 56. In 108 older adults after a hip fracture, 0.5–2.0 mg/day for 12 weeks raised lean mass 4.75–9.08% more than placebo.
What users report (anecdotal). According to a Reddit post from an individual who ran a 12-week LGD-4033 cycle, the substance helped him gain noticeable size, going from XL to 2XL shirts, which was significant given his tall, skinny frame.
Post-cycle, he also retained his strength and weight, shedding some water retention without losing muscle.
As expected, he still experienced testosterone suppression but was able to manage it with the use of Enclomiphene and maintained good liver health using N-acetylcysteine (NAC).
Another user also reported a great success with LGD-4033 for bulking, finding it effective with minimal side effects compared to other SARMs.
While he did experience acid reflux and some libido issues during the cycle, things returned to normal within three weeks post-cycle.
Over two cycles (60 days at 10mg/day), he added 80 lbs to his bench and gained significant muscle mass.
Note the doses: the trials used 0.1–2 mg/day; the users above describe 10 mg/day, ten times the highest dose tested in healthy men. Several case reports describe cholestatic liver injury, some confirmed by biopsy, in men using ligandrol products.
LGD-4033 in short
- Best human lean-mass data of any SARM for this goal (two placebo-controlled trials).
- Strength did not improve significantly in the 21-day trial.
- Suppresses testosterone even at 1 mg/day; lowers HDL cholesterol.
- Liver injury case reports with consumer products.
2. YK-11
YK-11 is often classified as a SARM, but it is a bit different from most.
To make it clear, YK-11 is a steroidal SARM because it is derived from DHT (dihydrotestosterone), which gives it properties closer to anabolic steroids.
What the studies show. Only lab studies exist. In cell studies it acted as a partial agonist of the androgen receptor, and in mouse muscle cells it raised follistatin, a protein that blocks myostatin. That is where the “myostatin inhibitor” label comes from; it has never been tested in a human or shown to block myostatin in a living body. No human trial, no human half-life and no safety data exist.
What users report (anecdotal).
According to the user, he experienced a significant increase in lean muscle mass after using YK-11, stating that it has given him far better results compared to using RAD-140 and LGD-4033.
Following this, he also felt better energy levels which led to a more intense workout session to the point that lifting weights has felt effortless to him.
On the flipside, there were negative effects too such as mild acne, shorter temper, mild insomnia, excessive sweating and anxiety in the first few weeks.
Another review was posted in response to the original post stating that YK-11 also helped him in his bulking progress.
He reported going from 90 kg to 109 kg in about three weeks. A change that fast cannot be all muscle.
In contrast to the original post, the user experienced minimal side effects, noting only a slight case of gynecomastia in his left nipple.
He reported using Nolvadex as part of his PCT, which has effectively aided in his recovery from gynecomastia.
YK-11 in short
- No human data of any kind; the myostatin story comes from cell studies.
- Steroid-based structure (derived from DHT); acts on the androgen receptor, so suppression is expected.
- Users commonly report aggression, anxiety, poor sleep, acne and, in some reports, gynecomastia.
3. RAD-140
RAD-140, commonly referred to as Testolone, is a widely favored SARM in the bodybuilding community, particularly for bulking phases.
What the studies show. RAD-140 has never been tested for muscle in people. In rats it grew muscle with less effect on the prostate, and in young male monkeys it raised body weight by over 10% in 28 days while cutting testosterone by about two-thirds. Its only human trial was in 22 women with advanced breast cancer: AST rose in 59% and ALT in 45% of patients, and serious liver-enzyme rises occurred in 23%. Several case reports describe liver injury in men using it.
What users report (anecdotal).
The user ran a 12-week cycle of RAD-140 with Enclomiphene and gained a total of 20 lbs. After which, he cut 10 lbs while still retaining 10 lbs of muscle. The progress is especially noticeable in his legs, shoulders, and triceps.
To note, most reviews in the same page indicate that RAD-140 is commonly paired with Enclomiphene as part of a post-cycle therapy (PCT) starting in the fourth week.
This approach helps users maintain their progress while minimizing the risk of severe or any side effects.
In another review, a user reported using RAD-140 during both his recomp and bulking phases.
During his recomp, he observed increased muscle size, particularly in his shoulders and chest, along with a significantly leaner physique due to maintaining a caloric deficit while taking 15 mg daily for eight consecutive weeks.
Upon returning to a bulking phase, he increased his dosage to 20 mg and noted substantial progress in muscle mass.
Users often describe side effects as mild, but the trial and case-report data above say otherwise for the liver.
Commonly reported side effects include minor mood changes, such as slight irritability, insomnia, and night sweats.
RAD-140 in short
- No human muscle data; animal data only.
- Testosterone not measured in men; strong suppression in monkeys.
- The highest liver risk score in our database (3 of 3).
4. Ostarine (MK-2866)
Ostarine is usually sold as a cutting or “beginner” SARM, but it has the most human data of any SARM. In older adults, 3 mg/day for 86 days added 1.3 kg of lean mass vs placebo and trimmed about 0.6 kg of fat. It lowered total testosterone (about 6–7 nmol/L) and HDL cholesterol (17–27%). Two Phase 3 trials in lung cancer patients missed their main goals. More in our ostarine fact sheet and the ostarine before and after page.
5. MK-677 (not a SARM)
MK-677 (ibutamoren) is a growth hormone secretagogue, not a SARM, but it is often added to bulking stacks. In healthy adults aged 60–81, 25 mg/day for 12 months raised fat-free mass by 1.1 kg (vs a 0.5 kg loss on placebo), but strength and function did not change and body weight rose 2.7 kg. Appetite went up in about two-thirds of people, water retention and muscle pain were common, and fasting glucose rose. In frail older adults after hip fracture, a heart-failure signal stopped one trial early. See the MK-677 hub and MK-677 side effects.
Ligandrol vs YK-11 vs RAD-140: which is best for bulking?
On evidence, LGD-4033 is the only one of the three with human lean-mass data, and it comes with proven suppression and lower HDL. RAD-140 and YK-11 may feel stronger to users, but there is no human study behind either for muscle, and RAD-140 carries the clearest liver signal. If the question is which compound has the most human research at all, the answer is ostarine. For a direct comparison see RAD-140 vs LGD-4033, YK-11 vs LGD-4033 and YK-11 vs RAD-140, or pick any two in the compare tool.
Source: Sarmguide compound database.
SARMs bulking stacks: what is known
Stacks are where marketing runs furthest ahead of the evidence. The three classic bulking stacks are LGD-4033 + MK-677, RAD-140 + MK-677 and YK-11 + cardarine. No study has tested any of them. Claims of “ten to fifteen pounds of muscle in eight weeks” come from user logs, not trials.
The only human data on a bulking combination is a case report: a 25-year-old man took 10 mg LGD-4033 and 15 mg MK-677 daily for 5 weeks while being tested. His total testosterone fell 62% and free testosterone 86%, HDL fell 36%, LDL rose 40%, ALT rose 205% and bone density fell 2.1%. Most values recovered after he stopped, but LDL and total cholesterol stayed higher.
Two facts from the original stack guides are worth keeping. MK-677 is not a PCT: it does not restore testosterone, it raises GH and IGF-1. And adding cardarine to a bulk adds a compound whose development was stopped after cancers in long-term animal studies. Our stack checker shows the overlapping risks of any combination, and the stack pages go deeper: LGD-4033 + MK-677, MK-677 + RAD-140, RAD-140 stacks and YK-11 stacks. SwissChems sells a ready-made RAD-140 + MK-677 + YK-11 value pack.
Side effects to expect on a bulk
Water retention and hunger
Both are well documented for MK-677: in a 12-month trial, more appetite affected 67% of people vs 36% on placebo, and leg swelling 19 of 43 vs 6 of 22. Users report the same with LGD-4033. Part of the weight gained on a bulk with these compounds is water.
Testosterone suppression
Every compound that acts on the androgen receptor lowers natural testosterone; for LGD-4033 this happens at 1 mg/day. See do SARMs lower testosterone? and SARMs PCT.
Liver strain
Case reports of cholestatic liver injury exist for LGD-4033, RAD-140 and ostarine products, and RAD-140 raised liver enzymes in about half the patients in its trial. The old advice to take “liver support” does not change that; a liver panel (ALT, AST, bilirubin) is how it is checked. See are SARMs liver toxic?
Cholesterol
HDL fell in the LGD-4033 and ostarine trials (17–27% for ostarine at 1–3 mg/day). That matters more over months of bulking.
Mood, aggression and acne
Users most often report these with YK-11 and RAD-140. There are no trial data; see do SARMs cause acne?
Is it legal?
The legal status of SARMs is complex and varies by region.
In the United States, no SARM is FDA-approved. The FDA says SARM products are unapproved drugs, not dietary supplements, and in December 2025 it sent warning letters naming products sold as LGD-4033, ostarine, MK-677 and cardarine.
Unlike anabolic steroids, SARMs are not classified as controlled substances, though organizations like the World Anti-Doping Agency (WADA) have banned their use in competitive sports.
In Australia, SARMs are prescription-only and possession without a prescription is illegal; cardarine is in Schedule 10 (prohibited). All of these compounds are banned in sport at all times. See are SARMs legal? for every country we track.
Before you consider any bulking compound
Check your health first
If you have any pre-existing conditions—like high blood pressure, liver problems, or hormonal imbalances—it’s best to consult with a doctor.
These substances can affect people differently, and certain health issues could make you more prone to side effects.
Know what is in the bottle
In a 2017 test of 44 products sold online as SARMs, only 52% contained a SARM and only 41% contained the amount on the label. A batch certificate of analysis from an independent lab is the minimum; our lab tests guide explains how to read one.
Bloodwork
The markers that moved in the trials are testosterone (total and free), LH, FSH, SHBG, HDL/LDL and liver enzymes, plus fasting glucose for MK-677. Our bloodwork guide lists them per compound.
Food and training still do the heavy lifting
It’s important to remember that SARMs should not be viewed as a quick fix for building muscle. Calories, protein and progressive training drive a bulk.
This, in turn, can enhance your performance and aid recovery during your bulking phase.
Be sure to include sufficient protein and healthy fats in your diet, as these nutrients are essential for supporting muscle growth and facilitating recovery after intense workouts.
Conclusion
If “best” means best evidence, LGD-4033 has the strongest human lean-mass data for a bulk and ostarine has the most human research overall; both lowered testosterone and HDL in trials. RAD-140 and YK-11 are popular but untested for muscle in people, and RAD-140 has the clearest liver signal. MK-677 adds weight partly as water, with more hunger and higher blood sugar. No stack has been studied. Compare them side by side in the compare tool, and see best SARMs for cutting and safest SARMs for the other goals.
Frequently asked questions
What is the best SARM for bulking?
None tested for bulkingEvidence: Trial
No SARM has been tested for bulking in healthy lifters. LGD-4033 has the best human lean-mass data (+1.21 kg in 21 days at 1 mg/day) but lowered testosterone and HDL; RAD-140 and YK-11 have no human muscle data.
Is ostarine good for bulking?
Modest effect in trialsEvidence: Trial
In older adults, 3 mg/day added 1.3 kg of lean mass vs placebo over 86 days. It also lowered total testosterone and HDL cholesterol.
Is RAD-140 the strongest SARM?
Never tested for muscle in peopleEvidence: Animal
In monkeys it raised body weight over 10% in 28 days and cut testosterone by about two-thirds. In its only human trial, liver-enzyme rises were common.
What is the best SARMs bulking stack?
No stack has been studiedEvidence: Limited
The only human data on a combination is a case report of LGD-4033 plus MK-677. It showed large drops in testosterone and HDL and a rise in LDL and liver enzymes after 5 weeks.
Will SARMs make me bigger?
Modestly, in trialsEvidence: Trial
In trials, LGD-4033 and ostarine added about 1–1.5 kg of lean mass over 3–12 weeks, mostly in older or ill people. Larger gains reported online cannot be checked and often include water.
What is the safest SARM to use?
None proven safeEvidence: Trial
No SARM is approved or proven safe. Ostarine has the most human safety data and LGD-4033 the next most; both lowered testosterone and HDL.
Do SARMs affect fertility?
They canEvidence: Trial
By lowering LH and FSH, androgen-receptor drugs reduce testosterone and sperm production. LGD-4033 lowered FSH at 1 mg/day in 21 days.
Is MK-677 good for bulking?
Small gain, with side effectsEvidence: Trial
MK-677 is not a SARM; over 12 months it raised fat-free mass by 1.1 kg in older adults, but strength did not change. Weight rose 2.7 kg, and appetite, water retention and blood sugar went up.
Sources
- The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men
- ClinicalTrials.gov NCT02578095: Acute Hip Fracture Study in Patients 65 Years or Greater (VK5211), posted results
- The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial
- A First-in-Human Phase 1 Study of a Novel Selective Androgen Receptor Modulator (SARM), RAD140, in ER+/HER2- Metastatic Breast Cancer
- Design, Synthesis, and Preclinical Characterization of the Selective Androgen Receptor Modulator (SARM) RAD140
- (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11) is a partial agonist of the androgen receptor
- Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
- Ligandrol (LGD-4033)-Induced Liver Injury
- Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet
- FDA: Certain bodybuilding products put consumers at risk for heart attack, stroke, serious liver damage and more (content current as of 2 December 2025)
- FDA Warning Letter to an online seller of products marketed as SARMs (MARCS-CMS 719257), 12 December 2025
- Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633)
