MOTS-c

What it is

Mitochondria are the power plants of your cells, and they have their own small genome, a remnant from the time when they were still independent bacteria. For a long time this mini-genome was considered nothing more than a blueprint for energy production. Then the research group led by Changhan David Lee and Pinchas Cohen at the University of Southern California found a short reading frame in it, hidden in the gene for 12S rRNA. It encodes a peptide of 16 amino acids: MOTS-c, in full mitochondrial open reading frame of the 12S rRNA-c.

This made it clear that mitochondria not only supply energy but also send messages. This is why it is called a mitokine, a hormone-like signal from the mitochondrion. MOTS-c is not alone: humanin, another peptide from mitochondrial DNA, which was discovered in connection with the protection of nerve cells, was already known. Together they form the young family of mitochondrial peptides, and within it MOTS-c is considered the metabolism specialist.

How it is supposed to work

The central lever is AMPK, the cell’s energy sensor. When energy becomes scarce, for example during exercise or fasting, AMPK kicks in and switches the cell to efficiency: more sugar uptake into muscle, more fat burning, more cleanup work. MOTS-c presses exactly this button. In the discovery paper, it inhibited the folate cycle and the associated de novo synthesis of purines, and through this AMPK became active. The main target organ appeared to be skeletal muscle. This is where the nickname “exercise in molecular form” comes from, and also the comparison with metformin, which likewise acts via AMPK.

The second part of the story is almost even more elegant. Under stress, for example glucose deprivation, MOTS-c moves into the cell nucleus in cell culture. There it regulates a whole series of genes, including ones with antioxidant response elements, and works together with the protective factor NRF2. So the power plant talks directly to the cell’s headquarters. For researchers, MOTS-c thus connects energy, metabolism and cell protection in one molecule.

Why the longevity scene is interested

Aging is to a good extent a story of declining mitochondria. A finding in humans fits this: in healthy men, MOTS-c in the blood was 11 percent lower in the 45-to-55 age group and 21 percent lower in the 70-to-81 age group than in 18- to 30-year-olds. The signal associated with fitness thus decreases in the blood.

The picture is not quite that simple, however. In the muscle of the same study, MOTS-c was around 1.5-fold higher in middle-aged and older men than in young men. The authors interpret this as part of the shift toward slower muscle fibers in old age. The often-told link to centenarians goes back to a 2015 paper that proposes a Northeast Asian gene variant in the MOTS-c region, m.1382A>C, as a possible contributor to the high life expectancy in Japan. That is a hypothesis about a gene variant, not a measurement of higher levels in very old people.

Who uses it and what is reported

Roughly three groups can be distinguished: people working on insulin sensitivity and body composition, endurance and performance athletes who want to boost the training effect, and longevity enthusiasts who are interested in mitochondria. The US Anti-Doping Agency describes MOTS-c as being heavily promoted by wellness and anti-aging clinics and on social media, above all as a weight-loss peptide.

User reports mainly mention more stable energy throughout the day, better endurance in training and a weaker afternoon slump. This fits the mechanism but remains a subjective report and is not proof of efficacy. In practice, MOTS-c is used as an injection under the skin, mostly in courses over a few weeks with breaks in between. We do not give a dosage here because MOTS-c is not an approved medicine.

What the studies show

Lee et al., Cell Metabolism 2015 — the discovery

The research group describes the short reading frame in the 12S rRNA and the 16-amino-acid peptide. In cells, MOTS-c inhibits the folate cycle and thereby activates AMPK; skeletal muscle appears to be the main target organ. In mice, administration of MOTS-c prevented age-dependent and diet-induced insulin resistance as well as obesity from a high-fat diet. The study contains no experiment in humans.

Reynolds et al., Nature Communications 2021 — performance and training

In the animal part, MOTS-c improved the running performance of mice aged 2, 12 and 22 months. After treatment, old animals ran 2-fold longer and 2.16-fold farther, and administration three times a week begun at 23.5 months of age improved their physical capacity. In the human part, 10 untrained, healthy young men cycled; MOTS-c rose 11.9-fold in muscle and 1.6-fold in the blood, and after 4 hours of rest the blood level was back at baseline. What was measured was the body’s own peptide; it was not administered to the participants.

D’Souza et al., Aging 2020 — levels in three age groups

Cross-sectional study in healthy men between 18 and 81 years of age. In the blood, MOTS-c was 11 percent below the level of the young men in 45- to 55-year-olds and 21 percent below it in 70- to 81-year-olds, whereas in muscle it was around 1.5-fold higher. Unlike in cell culture, the muscle level was not related to antioxidant protective genes. This shows how differently blood and tissue can be regulated.

Where the data stop

The decisive gap: there is no completed clinical trial in which humans received MOTS-c. The US Anti-Doping Agency also notes this. Since February 2, 2026, a randomized, placebo-controlled phase 2a trial with 120 planned adults with prediabetes and overweight has been recruiting (NCT07505745); results are expected in 2027 at the earliest. All statements on insulin sensitivity, endurance, body weight and cell protection rest on mice and cell cultures. Human data exist only as measurements of the body’s own level, for example after training, in age comparisons or in 107 patients after surgery with a heart-lung machine, in whom lower levels were associated with acute lung injury. A measured level shows that a signal is present, not that supplying it from outside has the same effect.

The longevity argument also holds only partly. The blood level falls with age, the muscle level rises. And the link to centenarians is a hypothesis about a gene variant, not an observation of higher levels. Whether MOTS-c injected in humans reaches the muscle and works there as it does in the mouse is open.

Status, approval and legal

MOTS-c is a research peptide and is not approved as a medicine in Germany or the EU; in the US, according to the US Anti-Doping Agency, it is approved by the FDA neither for human use nor for compounded medicines. On July 23–24, 2026, an FDA expert panel discussed whether MOTS-c should be permitted for compounded medicines in the US. The FDA’s own reviewers advised against it; the panel nonetheless voted in favor by majority (votes 7:5, 2 abstentions). An FDA decision is pending; a formal procedure is unlikely to begin before 2027. What is on the market is sold as a research product; purity and content are solely up to the supplier. In sport, MOTS-c has been named on the prohibited list since 2024 and is banned at all times, as an activator of AMP-activated protein kinase in the group of metabolic modulators. As a matter of principle, we do not give dosage information for non-approved substances.

Safety

There are no systematic safety data in humans because there are no completed clinical trials. In user reports, MOTS-c is considered well tolerated; reactions at the injection site are mentioned most often; that is a report, not tested tolerability. Since MOTS-c enhances insulin action in animals, it seems reasonable to be cautious when taking blood-sugar-lowering drugs at the same time, but this combination has not been studied. Anyone who takes diabetes medication or is pregnant or breastfeeding should stay away from it or talk to a physician beforehand. Competitive athletes risk a ban.

Sources

• Lee et al., Cell Metabolism 2015
• Kim et al., Cell Metabolism 2018
• Reynolds et al., Nature Communications 2021
• D’Souza et al., Aging 2020
• Fuku et al., Aging Cell 2015
• Shen et al., American Journal of Respiratory Cell and Molecular Biology 2025
• USADA: What is the MOTS-c peptide?
• USADA: Key changes 2024 Prohibited List
• WADA, Prohibited List 2026
• ClinicalTrials.gov NCT07505745 (MOTS-MET, phase 2a in prediabetes, recruiting since February 2, 2026)
• McDermott (law firm), report on the FDA compounding panel meeting of July 23–24, 2026