# MK-677: A Real Trial in Eight People, and a Liver Report

By Nora Bissett, Pricing Editor (https://glpwatchdog.org/authors/nora-bissett) | Published: 2026-08-21 | Updated: 2026-10-30

Canonical page: https://glpwatchdog.org/research/mk-677-nitrogen-balance-and-liver-injury

> A 1998 randomized crossover trial found MK-677 reversed diet-induced protein catabolism, moving nitrogen balance from -2.67 to +0.31 g/day. It enrolled eight people and measured a proxy. A 2025 case report describes liver injury after two months of use.

## Key points

- 1998 double-blind placebo-controlled crossover, 8 volunteers on 18 kcal/kg/day: nitrogen balance +0.31 g/day on MK-677 against -1.48 on placebo.
- Nitrogen balance is a proxy for protein retention, not a measure of muscle mass, strength or physical function.
- A 2025 BMJ case report describes raised liver enzymes in a healthy man in his early 30s after two months, resolving on stopping.
- MK-677 is a non-peptide growth hormone secretagogue sold as a research chemical, with no identity, purity or dose guarantee.

MK-677 is marketed to people losing weight who are worried about losing muscle, and there is a real trial behind that claim. In a double-blind, randomized, placebo-controlled crossover study, calorically restricted volunteers on MK-677 moved from negative to positive nitrogen balance while placebo stayed negative (+0.31 against −1.48 g/day, P < 0.01).[1] The trial had **eight participants**, ran the drug for seven days, and measured a laboratory proxy rather than muscle. A 2025 case report describes liver injury in a healthy man after two months of taking it.[2]

## The trial, and what it actually measured

Eight healthy volunteers aged 24 to 39 were calorically restricted to 18 kcal/kg/day for two 14-day periods. In the last seven days of each period they received either oral MK-677 25 mg once daily or placebo, with a washout of 14 to 21 days between. During the first week, on diet alone with no drug, nitrogen losses were essentially identical between the groups, which is a good sign that the design was working.[1]

*Mean daily nitrogen balance in each week (n = 8, crossover).[1]*

|   | Week 1 (diet alone) | Week 2 (diet + treatment) |
| --- | --- | --- |
| MK-677 | −2.67 ± 0.40 g/day | **+0.31 ± 0.21 g/day** |
| Placebo | −2.83 ± 0.26 g/day | −1.48 ± 0.21 g/day (P < 0.01) |

That is a clean result. On this endpoint, in this design, the drug did what it was supposed to. Crossing from nitrogen loss into nitrogen retention during a calorie deficit is not nothing.

> **Nitrogen balance is a proxy, not an outcome.** It estimates whether the body is retaining protein. It does not measure [muscle mass, muscle size, strength or physical function](https://glpwatchdog.org/research/peptides-for-muscle-growth), which are the things a person wants. And this is eight people over seven days of dosing in 1998. It is a reason to run a bigger study, and nobody appears to have run one that changes the picture.

## The liver report

In 2025 clinicians published the case of an otherwise healthy man in his early thirties who developed transaminitis (raised liver enzymes) after taking MK-677 for two months. Liver function tests returned to normal after he stopped. The authors note that reports of hepatotoxicity with this compound are scarce, while acknowledging its growing popularity as a performance supplement.[2]

One case is one case. It cannot tell you the risk, and this article is not going to imply a rate that nobody has measured. What it does establish is that liver injury is on the list of things that have happened, in a healthy young person, at a dose and duration that is unremarkable for how this compound is used.

The commoner reported effects (edema, increased appetite, muscle pain) matter too.[2] The appetite effect deserves thought if you are taking it alongside a drug whose entire purpose is to reduce appetite. The injectable peptide that works on the same receptor, [hexarelin](https://glpwatchdog.org/research/hexarelin-what-the-evidence-shows), showed no change in body fat or lean mass over 16 weeks. The longer MK-677 trials, and how the drug compares with prescription growth hormone, are in [MK-677 vs HGH](https://glpwatchdog.org/research/mk-677-vs-hgh).

## What it is, and what that means for what you buy

- MK-677 is a growth hormone secretagogue: an orally active non-peptide that prompts the body to release its own growth hormone. It is not itself a peptide, despite usually being sold alongside them.
- It is not an approved medicine. It is sold as a research chemical, outside the identity, purity and dose standards that apply to prescription drugs.
- The muscle-preservation case rests on a 1998 crossover trial in eight people measuring a proxy endpoint.
- Raising growth hormone and IGF-1 has implications that go beyond muscle. Anyone with a history of cancer, or with diabetes, has particular reason to take that to a clinician rather than a forum; [peptide blood work](https://glpwatchdog.org/research/peptide-blood-work-and-monitoring) covers what an IGF-1 test can and cannot tell you.

If muscle loss during weight loss is your concern, the interventions with real randomized support are covered in [what the body-composition studies measured](https://glpwatchdog.org/research/glp1-hair-loss-and-muscle-loss), [protein targets and the lab panel](https://glpwatchdog.org/research/protein-targets-and-the-lab-panel) and [bone density and exercise](https://glpwatchdog.org/research/glp1-bone-density-and-exercise). Resistance training is the one that keeps appearing. FDA's compounding listing for ibutamoren and the longer trials, including a two-year study in older adults, are summarized on our [MK-677 profile](https://glpwatchdog.org/peptides/mk-677).

## Frequently asked questions

### Does MK-677 preserve muscle while dieting?

A 1998 randomized, placebo-controlled crossover trial in eight calorically restricted volunteers found MK-677 moved nitrogen balance from negative to positive: +0.31 g/day against −1.48 on placebo. Nitrogen balance is a laboratory proxy for protein retention, not a measure of muscle mass, strength or function.

### Is MK-677 a peptide?

No. It is an orally active non-peptide growth hormone secretagogue that mimics the action of a growth-hormone-releasing peptide. It is usually sold alongside peptides but is a different kind of molecule.

### Can MK-677 damage your liver?

A 2025 case report describes an otherwise healthy man in his early 30s who developed raised liver enzymes after two months of use, which normalized after stopping. That is a single case and cannot tell you the risk, but it establishes that it has happened at ordinary use.

### Is it approved?

No. MK-677 is not an approved medicine and is sold as a research chemical, which means what you receive carries no guarantee of identity, purity or dose.

## References

1. Murphy MG, Plunkett LM, Gertz BJ, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. The Journal of Clinical Endocrinology and Metabolism. 1998. PMID: 9467534. https://pubmed.ncbi.nlm.nih.gov/9467534/
2. Cobani E, Amin MS, Hasso M, et al. Hepatotoxicity induced by MK-677. BMJ Case Reports. 2025. PMID: 40675653. https://pubmed.ncbi.nlm.nih.gov/40675653/

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Cite as: GLP Watchdog, Nora Bissett, "MK-677: A Real Trial in Eight People, and a Liver Report", published 2026-08-21, updated 2026-10-30. https://glpwatchdog.org/research/mk-677-nitrogen-balance-and-liver-injury

Canonical HTML page: https://glpwatchdog.org/research/mk-677-nitrogen-balance-and-liver-injury

Medical disclaimer: Nothing here is medical advice. We report on this subject; we do not treat anyone. Whether to begin a medication, supplement, or treatment, whether to adjust it, and whether to stop are questions for a clinician licensed to answer them, who knows your history.