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MOTS-c: from exercise-mimetic science to the FDA's compounding committee

Last updated: October 2, 2026 · 4 min read · By the Grey Peptides Editorial Board

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Grey Peptides
Grey Peptides Editorial Board
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Key takeaways
  • MOTS-c is a 16-amino-acid peptide coded not in the cell's nucleus but in mitochondrial DNA. In mice it improves how muscle handles glucose and boosts physical capacity, which is where the "exercise mimetic" label comes from.
  • The human evidence is observational: a genetic variant linked to diabetes, levels that rise with exercise or heat. No published trial has given MOTS-c to people and measured what it does.
  • In July 2026 the FDA's compounding committee voted 7 to 5 to recommend it for the 503A list, against its staff's advice; at our last check the FDA had not acted. WADA bans it by name in S4.4.1.

A peptide from mitochondrial DNA

MOTS-c Low was named in 2015, when researchers found that a short stretch inside the mitochondrial 12S rRNA gene encodes a 16-amino-acid peptide. In mice it regulated insulin sensitivity and metabolic balance, acting mainly on skeletal muscle, and it inhibited the folate cycle in a way that switched on AMPK, the cell's energy sensor 1. Under metabolic stress it moved into the cell nucleus in an AMPK-dependent way and changed the activity of genes that respond to glucose restriction and oxidative stress 2. Its levels in plasma fall with age, according to a 2023 review 3.

That chain, a mitochondrial signal that activates AMPK in muscle, is what exercise also does, and it is why MOTS-c is marketed as an exercise mimetic. The phrase describes a mechanism seen in mice, not an effect shown in people.

What the animal studies show

The most quoted study treated mice of three ages, 2, 12 and 22 months, and found MOTS-c significantly improved physical performance in all of them; intermittent treatment three times a week started at 23.5 months increased physical capacity and what the authors called healthspan 4. In another, mice with one leg immobilised for eight days lost about 15% of muscle mass, but only about 5% when given MOTS-c daily 5. These are well-designed animal experiments; they also used doses and schedules nobody has tested in people.

What is known in people

Everything in humans is observational. A variant of mitochondrial DNA found in East Asian populations, m.1382A>C, changes one amino acid of MOTS-c; in three cohorts totalling 27,527 people, men carrying it had more type 2 diabetes, but women did not 6. In a trial of exercise in breast-cancer survivors, MOTS-c levels rose after 16 weeks of training among non-Hispanic White participants 7. In 19 active men, repeated heat treatment raised circulating MOTS-c while a leg was immobilised 8. And because metformin shares much of its mechanism, researchers checked whether metformin raised MOTS-c in women with breast cancer; it did not 9.

What is missing is the study that matters: we found no published trial in which people were given MOTS-c and its effect on muscle, glucose or weight was measured. The doses sold online come from no human study.

The 2026 compounding committee vote

MOTS-c was one of seven peptides the FDA's Pharmacy Compounding Advisory Committee considered on July 23 and 24, 2026, for the list of substances pharmacies may compound under section 503A. FDA staff had proposed not adding any of them, citing inadequate chemical characterisation, missing information on immune reactions, insufficient evidence of effectiveness, and approved drugs already available for the nominated uses 10. For MOTS-c, nominated for obesity and osteoporosis, the committee voted 7 to 5 with two abstentions to recommend it anyway 10.

A committee vote is advice, not a decision. At our last check on September 25, 2026, the FDA had not added MOTS-c to the 503A list or moved it into Category 1, so the legal position for pharmacies was unchanged 10. Our PCAC page follows all seven.

Why it is banned in sport

WADA's 2026 Prohibited List names MOTS-c, written out as the mitochondrial open reading frame of the 12S rRNA-c, as an activator of AMPK under S4.4.1, alongside AICAR 11. It is therefore prohibited at all times. A ban based on a mechanism is not evidence that it enhances performance in humans; it reflects the mouse data and the class it belongs to.

Frequently asked questions

Is MOTS-c an exercise mimetic?

In mice it improves glucose handling in muscle and physical capacity through AMPK-linked pathways, which is why it is called one. No published trial has tested that in people.

Has MOTS-c been tested in humans?

Only observationally: a genetic variant linked to diabetes in men, and levels that rise with exercise or heat. We found no published trial of MOTS-c given to people.

Is MOTS-c legal to compound?

The FDA's compounding committee voted 7 to 5 in July 2026 to recommend it for the 503A list, against FDA staff advice. At our last check on September 25, 2026, the FDA had not acted, so it was not on the list.

Is MOTS-c banned by WADA?

Yes. The 2026 Prohibited List names it under S4.4.1 as an AMPK activator, prohibited at all times.

Sources

  1. Lee, C., et al. (2015). The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab, 21(3), 443-54. PMID: 25738459
  2. Kim, K. H., et al. (2018). The Mitochondrial-Encoded Peptide MOTS-c Translocates to the Nucleus to Regulate Nuclear Gene Expression in Response to Metabolic Stress. Cell Metab, 28(3), 516-524.e7. PMID: 29983246
  3. Zheng, Y., et al. (2023). MOTS-c: A promising mitochondrial-derived peptide for therapeutic exploitation. Front Endocrinol (Lausanne), 14, 1120533. PMID: 36761202
  4. Reynolds, J. C., et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun, 12(1), 470. PMID: 33473109
  5. Kumagai, H., et al. (2024). Mitochondrial-derived microprotein MOTS-c attenuates immobilization-induced skeletal muscle atrophy by suppressing lipid infiltration. Am J Physiol Endocrinol Metab, 326(3), E207-E214. PMID: 38170165
  6. Zempo, H., et al. (2021). A pro-diabetogenic mtDNA polymorphism in the mitochondrial-derived peptide, MOTS-c. Aging (Albany NY), 13(2), 1692-1717. PMID: 33468709
  7. Dieli-Conwright, C. M., et al. (2021). Effect of aerobic and resistance exercise on the mitochondrial peptide MOTS-c in Hispanic and Non-Hispanic White breast cancer survivors. Sci Rep, 11(1), 16916. PMID: 34413391
  8. Elhusseiny, R., et al. (2025). Repeated Heat Stress Modulates the Levels of the Mitokines MOTS-C and FGF21 in Active Men during Calf Muscle Immobilization. Med Sci Sports Exerc, 57(12), 2764-2774. PMID: 40674654
  9. Cuyàs, E., et al. (2022). Circulating levels of MOTS-c in patients with breast cancer treated with metformin. Aging (Albany NY), 15(4), 892-897. PMID: 36490309
  10. US FDA. Pharmacy Compounding Advisory Committee, July 23-24, 2026 meeting: briefing documents (posted June 29, 2026) and votes; status as of September 25, 2026. FDA
  11. World Anti-Doping Agency. Prohibited List 2026, section S4.4.1; read October 2, 2026. WADA

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.

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