At a glance: MOTS-c is a 16-amino-acid peptide that your mitochondria make naturally, discovered in 2015. In mice it improved insulin sensitivity, limited diet-induced weight gain and boosted physical performance in older animals. FDA's 2026 review found no human studies of MOTS-c itself. A related drug (CB4211) had mixed results in a small trial. It is not FDA-approved, an advisory panel voted 7 to 5 to recommend it for compounding against FDA staff advice, and it is banned in sport.
What is MOTS-c?
MOTS-c stands for mitochondrial open reading frame of the 12S rRNA type-c. It is a short peptide (16 amino acids) encoded not in the cell nucleus but in mitochondrial DNA, the small genome inside the cell's energy-producing structures. That makes it one of a new class of "mitochondrial-derived peptides."
It was discovered in 2015 by researchers at the University of Southern California, led by Changhan Lee and Pinchas Cohen. The body makes it naturally, especially in skeletal muscle, and levels appear to decline with age. Products sold online are lab-made.
How does MOTS-c work?
- Activates AMPK, the cell's energy sensor, which shifts cells toward burning glucose and fat, similar to some effects of exercise
- Improves glucose handling and insulin sensitivity in muscle, in mouse studies
- Moves into the nucleus under stress: a lab study found it travels to the cell nucleus during metabolic stress and switches on protective genes, a rare example of mitochondria directly signaling the nucleus
- Exercise-linked: in a small study of healthy young men, exercise raised MOTS-c levels in muscle and blood
FDA's review noted that its exact molecular targets are unknown and that it breaks down rapidly in human blood in lab tests.
What the research shows so far
| Study | Who was studied | Main finding |
|---|---|---|
| Lee et al., Cell Metabolism 2015 | Cells and mice | Improved insulin sensitivity; mice on a high-fat diet gained less weight and resisted metabolic changes |
| Reynolds et al., Nature Communications 2021 | Mice, plus 10 healthy young men | Treated young and old mice ran farther; older mice improved on walking, grip and gait tests. Exercise raised natural MOTS-c in men |
| CB4211 phase 1b (CohBar, 2021) | 20 adults with obesity and fatty liver, 4 weeks; CB4211 is a modified analog of MOTS-c | Liver enzymes (ALT, AST) and glucose improved vs placebo, but liver fat did not differ from placebo; injection-site reactions were common |
| MOTS-c itself in humans | None completed | FDA found no human studies; a 12-week phase 2a trial in about 120 adults with prediabetes (NCT07505745) is registered, with no results yet |
MOTS-c did not improve learning or memory in the mouse aging studies.
Why it gets attention
- "Exercise in a vial": its AMPK and exercise links make it popular in longevity and fitness circles
- Metabolic health and weight: promoted for insulin resistance, fat loss and obesity
- Healthy aging: physical performance gains in older mice drive anti-aging interest
- The 2026 FDA vote, which put it among six peptides recommended for compounding
How it is used
Products are sold for injection under the skin. Because there are no completed human trials of MOTS-c, there is no established human dose, and online protocols vary widely. This page does not provide dosing guidance.
What about side effects?
Human safety of MOTS-c is unknown because it has not been studied in people. In the CB4211 analog trial, the main side effect was mild to moderate injection-site reactions, with no serious adverse events, but that was a different molecule given for only four weeks.
- Blood sugar effects: because it acts on glucose metabolism, people with diabetes, prediabetes or on glucose-lowering medicines face unstudied risks, including low blood sugar.
- Immune reactions and quality: FDA flagged immunogenicity, peptide clumping and impurities, and found certificates of analysis that did not test for contaminants or endotoxins.
- No toxicology data: FDA found no standard repeat-dose, genetic, reproductive or cancer studies.
- Pregnancy and breastfeeding: not studied.
Regulatory status
- Not FDA-approved for any use.
- In April 2026 FDA removed MOTS-c from its "Category 2" safety-concern list after its nomination was withdrawn. That was not a safety finding.
- FDA reviewed it for obesity, insulin resistance, osteoporosis and related uses and recommended against adding it to the compounding list, citing no human data, poor characterization and unknown safety.
- On July 23, 2026 the advisory committee voted 7 to 5, with 2 abstentions, to recommend it anyway. The vote is non-binding, and formal rulemaking would be needed before compounding is allowed.
- MOTS-c is prohibited at all times by the World Anti-Doping Agency.
The bottom line
MOTS-c is a genuinely exciting discovery: a peptide made by mitochondria that, in mice, mimics some benefits of exercise and improves metabolism. But FDA found no human studies of MOTS-c itself, a related drug showed only partial benefits in a tiny trial, and the 2026 advisory vote did not approve it. Until real trials report, claims about fat loss, longevity or performance in people are unproven. Anyone with metabolic concerns should see a clinician about proven options.
Frequently asked questions
What is MOTS-c?
A 16-amino-acid peptide encoded in mitochondrial DNA, part of a newer class called mitochondria-derived peptides.
How is MOTS-c taken?
Injection in animal studies; no established human route.
Is MOTS-c FDA approved?
Not approved.
That means no regulator has reviewed its safety, effectiveness or manufacturing quality for this use.
What has research shown about MOTS-c?
- Insulin sensitivity and glucose metabolism in mice.
- Exercise capacity and age-related decline in mice.
What side effects have been reported?
- Not characterised in humans
Serious or less common risks are listed in the Side Effects section above.
What is still unknown about its safety?
Most of it. MOTS-c has not been through the trials that establish long-term safety in people, and products sold online are made by unregulated labs. Independent testing of online peptides has repeatedly found contents that do not match the label.
References
- Lee C, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism. 2015. View source
- Reynolds JC, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications. 2021. View source
- Kim KH, et al. The mitochondrial-encoded peptide MOTS-c translocates to the nucleus to regulate nuclear gene expression in response to metabolic stress. Cell Metabolism. 2018. View source
- FDA: Evaluation of MOTS-c and MOTS-c acetate for the 503A bulks list (July 2026 PCAC briefing). View source
- CohBar: Positive topline results from the phase 1a/1b study of CB4211 (August 2021). View source
- ClinicalTrials.gov: MOTS-MET phase 2a trial (NCT07505745). View source
- AJMC: FDA panel backs 6 peptides for compounding (July 2026). View source
- Rite Aid: MOTS-c overview. View source