MK-677

MK-677, also called ibutamoren or MK-0677, is an orally active non-peptide ghrelin mimetic and GH secretagogue. It is not growth hormone itself and is not a peptide. FDA states that ibutamoren is not approved and that its safety and efficacy have not been established. Oral activity does not make it an approved supplement or establish suitability for long-term use.

In the 65-person older-adult trial, MK-677 increased pulsatile GH and IGF-I. Maintaining a pulsatile hormone pattern did not establish a general safety advantage. Cortisol increased in this study, contradicting a blanket claim that ibutamoren never affects it. A hormone or nitrogen-balance change is not automatically a strength or recovery benefit.

The randomized trial enrolled 65 healthy adults aged 60–81 in a two-year modified-crossover design, with primary endpoints at one year. Fat-free mass changed by +1.1 kg with MK-677 versus −0.5 kg with placebo. Body weight increased by 2.7 versus 0.8 kg; abdominal visceral fat and total fat mass did not differ significantly. Increased fat-free mass did not improve strength or function, and the study was underpowered for functional endpoints.

Fasting glucose increased by about 5 mg/dL and insulin sensitivity decreased. Mild edema, appetite increase and muscle pain occurred. The favorable lean-mass finding should be preserved alongside these outcomes, rather than rewritten as established fat loss, stronger muscles or a clean long-term safety record.

A small sleep study found increased stage-IV and REM sleep with high-dose MK-677 in eight young adults over seven-day crossover periods. Six older adults were studied over two 14-day periods and had improved REM-related measures. These are encouraging short-term findings, not established chronic insomnia treatment or a universal bedtime protocol.

In eight calorie-restricted volunteers, seven days of MK-677 improved mean daily nitrogen balance to +0.31 g/day versus −1.48 with placebo. That supports a short-term anabolic research direction, but nitrogen balance is not a direct demonstration of training recovery, long-term hypertrophy or athletic performance.

The older-adult study used 25 mg orally once daily; it did not establish a routine split-dose schedule, optimal benefit-risk dose, general bodybuilding cycle or self-treatment protocol. Short sleep and diet-restriction experiments used different designs and cannot define safe chronic administration. Product identity and quality remain separate from the pharmacology of a named research compound.

In a 123-person hip-fracture trial, 25 mg/day increased IGF-I, and gait speed improved on one measure, but most functional measures did not. Stair-climbing power was not significantly improved (P=0.292), and the fewer-falls observation was also nonsignificant (P=0.096). The trial ended early after a congestive-heart-failure safety signal in a limited number of patients; the authors judged the safety profile unfavorable in this population.

FDA’s compound-specific record highlights that heart-failure potential, and its consumer alert also describes fluid retention, fatigue, muscle pain and glucose/insulin effects. This does not show that every user will develop heart failure, but it rules out describing the evidence as uniformly free of major safety concerns. Findings in healthy older volunteers cannot settle risk in frail patients or prove rare-event safety.

The cited studies do not validate combining ibutamoren with CJC-1295, GHRP-6, testosterone or SARMs for superior outcomes or safety. FDA warns of potentially harmful interactions with medications and products such as SARMs. Useful lean-mass, sleep and nitrogen-balance observations remain research findings with population and duration limits; they do not establish a general stack or protective cycling schedule.

Editorial source check dated October 26, 2026. Linked primary abstracts and relevant official product or regulatory sections were read; journal full texts and every library page in this compound family were not reviewed. This is not clinician sign-off or an individualized treatment assessment.