Ibutamoren MK-677 and Hypertrophy: How Much Muscle Can You Gain?
MK-677 (Ibutamoren) has gained popularity in the fitness world for its potential to boost muscle growth. If you're familiar with this compound, you'll know that it's been credited with notable effects on hypertrophy. But how true are these claims, and what are the real risks?
This blog delves into scientific evidence and user experiences to provide a clear perspective on the effects of MK-677 on muscle mass gain.
How does MK-677 work?
Unlike SARMs, Ibutamoren is an oral growth hormone (GH) secretagogue . It works by mimicking ghrelin, stimulating GH release and, consequently, elevating levels of insulin-like growth factor 1 (IGF-1), a key hormone in anabolic processes.
In theory, more GH and IGF-1 should translate into more muscle. But does practice support this theory?
MK-677 and Muscle Gains
Clinical research on MK-677 has yielded interesting results, although with important nuances for those seeking hypertrophy:
Increased Lean Mass: Several studies, especially in older adults or people with obesity, have shown that MK-677 can increase lean body mass. For example, one study in older adults reported a 1.1 kg increase in lean mass after one year with 25 mg/day. Another study in obese men showed an increase of approximately 3 kg in lean mass in 8 weeks. Even in healthy volunteers under calorie restriction, MK-677 reversed protein loss, suggesting an anabolic or muscle-sparing effect.
But What Kind of Lean Mass? This is where things get complicated. Part of the increase in Lean Mass appears to be due to an increase in intracellular water and fluid retention, a common side effect. This means that not all of the "gain" is pure contractile muscle tissue.
What about strength? Surprisingly, despite increased lean mass, most clinical trials (especially in older populations) have found no significant improvements in muscle strength or physical function . This disconnect is crucial: If mass gain doesn't make you stronger or more functional, does it really meet an athlete's or bodybuilder's hypertrophy goals?
Possible Desensitization: A study in rats suggested that after 6 weeks of continuous use, the GH-stimulating effect diminished, raising questions about long-term effectiveness.
Experiences and opinions about Ibutamoren Mk-677
In forums and online communities, user reports paint a mixed picture:
Muscle "Fullness": Many users report feeling "fuller" or "rounder." This effect is most likely linked to the fluid retention we mentioned.
Increased Appetite: This is one of the most consistently reported effects. For some in the bulking phase, this could be an advantage if managed with a quality diet. For others, it can lead to excessive caloric intake and fat gain.
Strength Gains: Some users claim to have gained strength, but these reports are usually anecdotal, and in many cases, MK-677 is used in conjunction with other compounds (such as SARMs), making it difficult to attribute the gains solely to Ibutamoren.
Skin and Hair Improvements: Some users notice secondary aesthetic improvements, possibly related to the increase in GH/IGF-1.
Possible Side Effects of MK-677
This is where the balance can tip decisively:
Uncontrolled Increased Appetite: Can sabotage a clean diet and contribute to metabolic problems if not managed carefully.
Decreased Insulin Sensitivity: This is a major concern. With prolonged use, MK-677 can increase blood glucose levels and make your body less responsive to insulin. This is not only detrimental to your overall health, but could also hinder your muscle gains.
Lethargy and Fatigue: Some users experience fatigue, which could negatively affect training intensity.
Cardiovascular Risks: A study in elderly patients with hip fractures was stopped prematurely due to a sign of possible congestive heart failure. Although the population was specific, it is a red flag.
Unknown Long-Term Effects: There are not enough long-term studies in healthy individuals using MK-677 for cosmetic purposes.
MK-677 for Hypertrophy: A Realistic Perspective
If we put all the pieces together:
MK-677 may increase lean body mass, but a significant portion of this gain could simply be water.
The evidence that this increase in Lean Mass translates into significant functional strength gains in healthy, trained individuals is weak at best.
The health risks, especially those related to glucose metabolism and insulin sensitivity, are serious and should not be taken lightly.
Literature
Nass, R., Pezzoli, S.S., Oliveri, M.C., et al. (2008). Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized, controlled trial. Annals of Internal Medicine , 149(9), 601-611.
Svensson, J., Lönn, L., Jansson, JO, et al. (1998). Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. The Journal of Clinical Endocrinology & Metabolism , 83(2), 362-369.
Murphy, M.G., Plunkett, L.M., Gertz, B.J., et al. (1998). MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. The Journal of Clinical Endocrinology & Metabolism , 83(2), 320-325.
Adunsky, A., Chandler, J., Heyden, N., et al. (2011). MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Archives of Gerontology and Geriatrics , 53(2), 183-189.
Camacho-Arroyo, I., Cartmill, D., Clarke, IJ, et al. (2000). Prolonged administration of the growth hormone secretagogue, MK-0677, abolishes its stimulatory effect on GH secretion in rats by increasing hypothalamic somatostatin. Endocrinology , 141(11), 4005-4011.
Cardaci, TD, Sgromolo, NM, El Salamouny, AM, et al. (2022). Combined Use of LGD-4033 and MK-677 in a 25-Year-Old Male: A Case Report. Journal of Dietary Supplements , 19(6), 806-817.