MK-677 (Ibutamoren)

MK-677 is a small-molecule research compound investigated for its effects on growth hormone signaling. Although the supplied material categorizes it as a peptide, ibutamoren is not a peptide, and changes in hormone concentrations do not establish therapeutic benefit.

Ghrelin receptor signaling participates in appetite regulation and the control of growth hormone secretion. Growth hormone influences production of insulin-like growth factor 1, which contributes to growth-related processes in muscle, bone, and other tissues.

Ibutamoren has been studied as an agonist at the ghrelin receptor, with downstream effects on growth hormone secretion and insulin-like growth factor 1 concentrations. Its receptor activity also provides a biological basis for appetite-related effects. Proposed effects on sleep and recovery require separate evaluation rather than being assumed from hormonal changes.

1. 01

   Molecular target

2. 02

   Cellular signal

3. 03

   Biological process

LEVEL 03 · Early human research

Small or early-stage human studies exist, with limited certainty and reproducibility.

Evidence levels reflect the state of documented research only. They are not rankings of popularity, quality or suitability, and a higher level never implies that a compound is an approved medicine.

The source guide presents ibutamoren as a compound that activates ghrelin-related signaling and increases growth-related hormone secretion. It associates these effects with potential changes in muscle, lipid metabolism, skeletal health, sleep, and age-related physiology. The guide characterizes tolerability favorably while also describing appetite changes, fluid accumulation, fatigue, and disturbances in glucose regulation; its favorable assessment should not be treated as an established safety conclusion.

Source: The Complete Guide to Peptides: Unlocking the Secrets to Health, Healing and Longevity — Hack Smith, Chapter 6, Introduction to Peptides (page references not verified)

Summarised in our own wording from the cited reference. The reference is a popular guide, not peer-reviewed literature; its statements are reported here as source claims rather than established facts.

Dosage, reconstitution and administration guidance is deliberately excluded from this platform.

The supplied notes do not establish whether hormonal effects translate into meaningful improvements in physical function, skeletal outcomes, or age-related health. Claims concerning recovery, fat reduction, and longevity remain insufficiently supported by the information provided.

Reported concerns include heightened hunger, fluid accumulation, tiredness, elevated blood glucose, and reduced insulin sensitivity. Safety data are limited, particularly for prolonged exposure, and the consequences of sustained growth hormone and insulin-like growth factor 1 elevation remain uncertain. This information is not medical advice.

Research-stage compound unless otherwise established by a competent authority. Regulatory classification differs between jurisdictions and can change over time; nothing here indicates marketing authorisation.

Primary reference for this entry:

The Complete Guide to Peptides: Unlocking the Secrets to Health, Healing and Longevity — Hack Smith, Chapter 6, Introduction to Peptides (page references not verified)

Suggested literature search terms taken from the source. They are search starting points, not citations to specific studies.

• “MK-677 (Ibutamoren) growth hormone release”
• “MK-677 peptide fat loss and muscle growth”
• “Clinical trials MK-677 for aging and muscle mass”

Editorial status

source reviewed

Last updated

2026-09-14

Last reviewed

2026-09-13

Language

EN