Ostarine (MK-2866) Stacks: Cutting, Bulking and Strength

Short answer: the most common ostarine (MK-2866) stacks are with cardarine for cutting, MK-677 for bulking, RAD-140 for recomposition and LGD-4033 for strength. None of these stacks has been studied. Ostarine itself has the most human data of any SARM: at 3 mg a day for 86 days it added 1.3 kg of lean mass vs placebo, and lowered HDL cholesterol by 27% and total testosterone in men (Dalton 2011). Each partner adds its own risks, so check combinations with the stack checker.

What To Avoid

Before constructing a stack we need to go over a few things to keep in mind.

Firstly, users generally keep stacks to about 8 weeks. Longer cycles mean longer exposure to suppression and lipid changes; no study has measured how suppression grows with cycle length for any stack.

Secondly, we shouldn’t stack Ostarine with some of the most suppressive SARMs like YK11 or S23.

Adding a second androgen-receptor drug adds suppression from both. S-23 cut LH by more than half in rats (Jones 2009), and YK11 has never been measured in people.

Finally, bloodwork before and after (testosterone, SHBG, HDL/LDL, liver enzymes) is the only way to know whether you need PCT; the PCT and bloodwork planner lists the markers.

Ostarine Stack For Cutting

Evidence level: anecdotal. No ostarine stack has been studied. The doses are what users commonly report (kept from the original article), several times the 1–3 mg a day tested for ostarine.

The classic cutting stack is ostarine + cardarine, commonly reported at 10–15 mg ostarine and 10 mg cardarine a day for 8 weeks.

What each part is known to do: ostarine adds lean mass and, in older adults losing weight on semaglutide, 3–6 mg a day cut lean-mass loss by 71% over 16 weeks (company data, Veru 2025). Cardarine improved blood fats in human trials of 2–12 weeks, but fat loss and endurance were never measured in people, and its development stopped after two-year animal studies found cancers in many organs (GSK letter, 2013). Cardarine does not act on the androgen receptor, so any suppression comes from the ostarine.

Cardarine Ostarine stack results

The original cardarine-ostarine article (now merged here) reported seasoned users losing 8–10% body fat and 10–15 lb in 8 weeks while keeping most of their muscle. Those are user reports, from people who were also dieting. Reader photos of this stack are on the ostarine before and after and cardarine before and after pages.

Cardarine Ostarine stack side effects

• Suppression (ostarine): total testosterone fell about 6–7 nmol/L at 1–3 mg a day (Dalton 2011); the original author found ostarine “quite suppressive” at user doses.
• Headaches (ostarine): the most common side effect in the 86-day trial, usually early.
• Lower HDL (ostarine) by 17–27%.
• Liver: ALT rose with ostarine in trials, and a 43-year-old man using cardarine with ostarine had severe liver damage and muscle breakdown (ALT up to 922 U/L, CPK up to 86,435 U/L), recovering over about 6 weeks (Kintz 2021). The old claim that milk thistle or TUDCA “has been scientifically proven” to prevent this has been removed; a liver panel before and during use is how damage is caught. See are SARMs liver toxic.
• Cancer (cardarine, animal data): tumors in many organs in two-year rat and mouse studies (SOT 2009).

Cardarine Ostarine stack PCT

The original article said this stack never needs PCT at its doses. That isn’t established: ostarine lowered testosterone at much lower doses in trials, and recovery after 10–15 mg a day has not been studied. Bloodwork at the end of the cycle answers the question; see ostarine PCT.

Ostarine Stack For Bulking

Evidence level: anecdotal. No ostarine stack has been studied. The doses are what users commonly report (kept from the original article), several times the 1–3 mg a day tested for ostarine.

Commonly reported: ostarine 15 mg a day for 8 weeks with MK-677 15 mg a day for 12–16 weeks.

What MK-677 is known to do: it is a growth hormone secretagogue, not a SARM. Over 12 months in older adults, 25 mg a day raised IGF-1 1.5-fold and fat-free mass by 1.1 kg vs a loss on placebo, with more appetite (67% vs 36%), water retention and higher fasting glucose (Nass 2008). It is not a PCT: in obese men, 8 weeks lowered total testosterone vs placebo (Svensson 1999), so continuing it after ostarine does not help testosterone recover. The old claims that it improves hair and skin have no trial support. See the MK-677 fact sheet and MK-677 as PCT.

Ostarine Stack For Body Recomposition

Evidence level: anecdotal. No ostarine stack has been studied. The doses are what users commonly report (kept from the original article), several times the 1–3 mg a day tested for ostarine.

Commonly reported: ostarine 10 mg plus RAD-140 10 mg a day for 8 weeks at maintenance calories.

What RAD-140 is known to do: it has never been tested for muscle in people. In its only trial, in women with advanced breast cancer, AST and ALT rose in 59% and 45% of patients (LoRusso 2022), and in young male monkeys it cut testosterone by about two-thirds in 28 days (Miller 2011). Stacking it with ostarine combines two suppressive compounds and two liver signals. More: RAD-140 stacks.

Ostarine Stack For Strength

Evidence level: anecdotal. No ostarine stack has been studied. The doses are what users commonly report (kept from the original article), several times the 1–3 mg a day tested for ostarine.

Commonly reported: ostarine 10 mg plus LGD-4033 5 mg a day for 8 weeks.

What LGD-4033 is known to do: in healthy young men, 1 mg a day for 21 days added 1.21 kg of lean mass, but leg-press strength and stair-climb power did not change significantly; testosterone, SHBG and HDL fell with dose (Basaria 2013). The reported 5 mg is five times that. Both compounds lower HDL and testosterone, so the stack adds those effects together. See LGD-4033 PCT.

Conclusion

Ostarine is stacked with cardarine, MK-677, RAD-140 and LGD-4033 for different goals, but no stack has been studied, and the reported ostarine doses are several times what was tested. What is known: ostarine lowers HDL and testosterone and can raise liver enzymes; cardarine has animal cancer findings; MK-677 raises appetite and blood sugar and is not a PCT; RAD-140 and LGD-4033 add their own suppression. Get bloodwork before and after any stack, and compare compounds in the SARMs database.