SARMs Explained: What You Need to Know

Mechanism: tissue selectivity in practice

A SARM binds to the androgen receptor — the same receptor that testosterone and anabolic steroids target. Its peculiarity is differential affinity across tissues: high in muscle and bone, low in skin, hair or prostate ^[2]. On paper, you get the anabolic muscle effect without the share of classic androgenic side effects. In practice, selectivity is never total, and dose changes the equation — at high doses, part of the effects you tried to avoid come back.

The advertised anabolic/androgenic ratio is typically very favorable: 90/1 for RAD-140 (Testolone), 100/10 for LGD-4033 (Ligandrol), 100/33 for Ostarine (MK-2866) (compared with 100/100 for testosterone). That does not mean zero androgenic effect, but a strong imbalance toward anabolic muscle action — less acne, less hair impact for most users.

The main compounds: profiles and ranges

Ostarine: the entry point

Ostarine is the most studied and best tolerated SARM. Typical range: 10 to 30 mg/day, in a single dose. Mild suppression under 20 mg/day for most users, enough for body recomposition and lean-mass preservation during cuts. A mini-PCT (Nolvadex 20 mg/day over 4 weeks) is often sufficient. 8 to 12-week cycles.

LGD-4033: the most anabolic

LGD-4033 (Ligandrol) is the most anabolic SARM available: gains at 5–10 mg/day are comparable to a low-dose testosterone run, but HPTA suppression is marked — often at the level of a light cycle ^[3]. Full PCT recommended (Nolvadex 40/40/20/20 mg). 8 to 10-week cycles.

RAD-140: the most potent

RAD-140 (Testolone) is considered the most potent SARM. Excellent paper anabolic/androgenic ratio (90/1), notable strength gains. Typical dose 5 to 15 mg/day. Significant HPTA suppression, sometimes felt aggression, possible hair signals at high dose. Full PCT mandatory. Short cycles (6 to 8 weeks).

MK-677 and Cardarine: two molecules apart

MK-677 (Ibutamoren) is not a SARM: it is a growth hormone secretagogue. It does not act on the androgen receptor and does not suppress the HPTA. Half-life 24 h, single dose in the evening. Effects expected over 4 to 12 weeks: recovery, sleep quality, mild IGF-1 increase, increased appetite. Glucose/HbA1c monitoring for extended use (possible insulin resistance).

Cardarine (GW-501516) is not a SARM either: it is a PPARδ agonist that acts on metabolism and endurance. Marked lipolysis, improved cardiovascular endurance, mild HDL increase. Dose 10 to 20 mg/day. No HPTA suppression.

HPTA suppression: what bloods actually show

HPTA suppression on SARMs is documented by several short clinical studies and by post-cycle bloods on r/sarmssourcetalk and MESO-Rx ^[1]. Three orders of magnitude stand out.

• Ostarine 10–20 mg over 8 weeks. Mild to moderate suppression in most users; LH and FSH typically at 30–60% of baseline at end of cycle, total testosterone reduced but often within the low-normal range. Quick recovery (4 to 6 weeks) with mini-PCT.
• LGD-4033 5–10 mg over 8 weeks. Marked suppression comparable to a contained-dose testosterone cycle. LH/FSH crashed at end of cycle, total testosterone very low. Full PCT required.
• RAD-140 10–15 mg over 6–8 weeks. Suppression similar to LGD. Plus felt aggression and possible mild transaminase elevation in some users.

Without before/after bloods, these orders of magnitude remain averages: individual response varies. The hormonal markers guide details how to read LH, FSH and testosterone post-SARMs.

Product quality: the Achilles' heel

The SARMs market is less regulated than the historic underground steroid labs. The few independent analyses that exist (associative toxicology labs, studies published in 2017 and 2020 on products bought online) have routinely found underdosed products, products containing undeclared prohormones (which do aromatize and are hepatotoxic) or simple placebos. When marketing promises 'SARM 99% pure, third-party certificate', the origin of that certificate has to be verifiable.

• A SARMs cycle with no bloods (LH/FSH/testosterone before and after) cannot tell you whether the product was active — and any conclusion on "what it did" is subjective.
• A verifiable certificate of analysis comes from an identified lab, with a reproducible batch number, and the vendor authorizes counter-testing.
• Underdosing explains "disappointing" cycles far more often than users assume.
• Substitution by a prohormone explains a cycle that is "much harder than expected" (gyno on Ostarine, for example).

PCT and cycle structure

PCT logic is the same as for a steroid cycle: restore endogenous testosterone production as fast and as completely as possible after the compound ends. Protocol details are in the SARMs PCT guide. Summary:

• Ostarine at contained dose. Mini-PCT with Nolvadex 20 mg/day for 4 weeks, if felt or measured suppression is mild.
• LGD-4033, RAD-140, or high-dose Ostarine. Full PCT Nolvadex 40/40/20/20 mg (4 weeks), sometimes Clomid 50/50/25/25 mg if severe suppression measured. See the Nolvadex vs Clomid guide.
• MK-677, Cardarine, GH secretagogues. No PCT required — no HPTA suppression.

Calculating the delay between the last dose and the PCT start is simpler than with long esters: SARMs half-lives being short (15 to 36 h), a PCT started 1 to 3 days after the last dose is consistent. The when to start PCT guide gives the general logic, and the half-life calculator helps pin down the timing.

Realistic expectations: what SARMs do (and do not)

What SARMs do well: clean recomp (Ostarine), muscle preservation during cuts, notable strength gains (RAD-140), moderate lean bulk (LGD-4033), improved recovery (MK-677), endurance (Cardarine). On a trained user, gains of 2 to 5 kg of muscle mass over an 8 to 10-week LGD or RAD cycle are common — well below what a testosterone cycle at effective doses delivers, but with no injection.

What SARMs do not do: they do not replace a steroid cycle for users chasing maximum mass; they are not 'suppression-free'; they do not waive blood monitoring; and they do not have the long-term clinical track record of steroids. Safety over 10, 20 or 30 years of repeated use remains unknown.

For users starting with SARMs rather than steroids, the first SARMs cycle guide develops the approach step by step.

Frequently asked questions