MOTS-c is a 16-amino-acid peptide whose instructions are written in mitochondrial DNA, not in the cell nucleus where almost all human genes live. Discovered in 2015 at the University of Southern California, it acts mainly on skeletal muscle, activates the energy sensor AMPK, and rises in the blood and muscle during exercise, which is why it is nicknamed an “exercise mimetic.”
In mice, MOTS-c prevented diet-induced obesity and insulin resistance and improved physical performance even when started in old age. In humans, the evidence is still limited to measurements of natural MOTS-c levels and one small early trial of a related drug. In July 2026 an FDA advisory committee voted 7–5 to recommend it for the US compounding list, and since 2025 it has been explicitly prohibited in sport by WADA.
What MOTS-c is
MOTS-c stands for Mitochondrial Open reading frame of the Twelve S rRNA type-c. That mouthful describes where it comes from: a short stretch of code hidden inside the mitochondrial gene for 12S ribosomal RNA, a gene previously thought to code only for a structural RNA, not a protein.
| Property | Detail |
|---|---|
| Length | 16 amino acids |
| Sequence | MRWQEMGYIFYPRKLR |
| Encoded in | Mitochondrial DNA (12S rRNA gene, MT-RNR1) |
| Discovered | 2015, Lee and Cohen labs, University of Southern California |
| Main target tissue | Skeletal muscle |
| Key pathway | AMPK activation |
| Found in | Blood, muscle and other tissues in humans and mice |
| Approved as a drug? | No, anywhere |
It belongs to a small family called mitochondrial-derived peptides (MDPs), along with humanin (discovered in 2001) and the SHLP peptides. MOTS-c is the one that has attracted the most metabolic research.
Why a mitochondrial-encoded peptide is a big deal
Mitochondria are the cell’s power plants, and they are descended from bacteria that were absorbed by our single-celled ancestors about two billion years ago. They still carry their own small genome: 16,569 DNA letters in humans, inherited from the mother, coding for just 13 proteins, 22 transfer RNAs and 2 ribosomal RNAs.
For decades, that list was considered complete. The discovery of MDPs showed that mitochondrial DNA contains additional short open reading frames hidden inside known genes, and that some of them make peptides that leave the mitochondria and act as hormones, signalling to other organs. That turned mitochondria from passive power plants into active participants in the body’s communication network. It also suggested that the mitochondrial genome, and the variations in it between people, could affect metabolism and aging in ways nobody had looked for.
The 2015 discovery
MOTS-c was described in Cell Metabolism in March 2015 by Changhan David Lee, Pinchas Cohen and colleagues. Searching the mitochondrial genome for short open reading frames, they found one in the 12S rRNA gene that coded for a 16-amino-acid peptide, then showed that the peptide was actually present in tissues and blood.
Their key experiments, in mice:
- Diet-induced obesity: mice fed a high-fat diet and treated with MOTS-c gained less weight and fat than untreated mice.
- Insulin resistance: MOTS-c-treated mice kept better insulin sensitivity on the high-fat diet, and MOTS-c reversed age-related insulin resistance in older mice.
- Target tissue: the effects were concentrated in skeletal muscle, where MOTS-c increased glucose uptake.
The paper framed MOTS-c as a mitochondrial signal that regulates whole-body metabolism, which is a reasonable summary of the field’s view ever since.
MOTS-c timeline
| Year | Milestone |
|---|---|
| 2001 | Humanin, the first mitochondrial-derived peptide, is discovered |
| 2015 | MOTS-c described in Cell Metabolism: prevents diet-induced obesity and insulin resistance in mice |
| 2018 | MOTS-c shown to move into the nucleus and regulate nuclear genes under stress |
| 2021 | Exercise shown to raise MOTS-c in humans; late-life treatment improves physical capacity in old mice |
| 2021 | CohBar reports early-phase results for the analogue CB4211 |
| 2022 | K14Q variant linked to muscle fibre composition in Japanese cohorts |
| 2024 | Studies on muscle atrophy and direct activation of CK2 |
| 2025 | Named on the WADA Prohibited List (S4, AMPK activators) |
| 2026 | FDA advisory committee votes 7–5 to recommend it for the US compounding list |
How it works: AMPK, the folate cycle and the nucleus
The proposed mechanism runs through a chain of steps, which is worth understanding because it explains both the “exercise mimetic” label and the WADA ban.
- Folate cycle inhibition. MOTS-c inhibits the folate cycle and the downstream de novo purine synthesis pathway.
- AICAR accumulation. This causes a build-up of AICAR, a natural intermediate of purine synthesis.
- AMPK activation. AICAR activates AMPK, the cell’s master energy sensor, which is normally switched on when energy is low, as during exercise.
- Metabolic switch. Active AMPK increases glucose uptake and fat burning, and promotes mitochondrial biogenesis.
A 2018 study added a twist: under metabolic stress, MOTS-c moves into the cell nucleus and regulates nuclear genes, including antioxidant response genes. That makes MOTS-c a messenger from the mitochondrial genome to the nuclear genome, a two-way conversation between the cell’s two sets of DNA. A 2024 study reported that MOTS-c also directly binds and activates the enzyme CK2 in muscle, a further pathway linking it to muscle function.
AICAR itself, a synthetic version of the same intermediate, was banned by WADA years ago after it was shown to boost endurance in sedentary mice. MOTS-c’s mechanism runs through the same pathway, which is a large part of why it’s now explicitly banned in sport.
The exercise connection
The nickname “exercise mimetic” rests on two observations:
- Exercise raises MOTS-c. In the 2021 Nature Communications study, a bout of exercise in healthy young adults increased MOTS-c in skeletal muscle about 12-fold and raised blood levels as well, returning toward baseline after rest.
- MOTS-c reproduces some effects of exercise. In mice, it increased running capacity and improved muscle metabolism, effects similar to those of training.
A caution on the label: “exercise mimetic” has been applied to a long list of compounds, including AICAR and GW501516, none of which reproduces the full range of exercise benefits for the heart, brain, bones and mood. MOTS-c may be one of the signals that mediates exercise’s metabolic effects. That doesn’t make it a substitute for exercise.
Aging and physical decline: the 2021 study
The most striking MOTS-c results come from Reynolds and colleagues (2021). In mice:
- MOTS-c improved physical performance in young (2 months), middle-aged (12 months) and old (22 months) mice.
- Treatment started in very late life (23.5 months, roughly equivalent to a human in their 70s) and given three times a week improved physical capacity and healthspan.
- MOTS-c regulated nuclear genes related to metabolism and protein quality control and helped muscle cells adapt to metabolic stress.
The authors concluded that aging is regulated by genes encoded in both the mitochondrial and nuclear genomes. It’s an important finding, but it is a mouse healthspan finding, and no human aging trial has been done. For context on the wider field, see Longevity peptides.
Muscle wasting research
A line of work from Japanese and US groups has looked at whether MOTS-c protects muscle under conditions that cause wasting:
- Myostatin: a 2021 study found MOTS-c reduced myostatin, a brake on muscle growth, and muscle atrophy signalling in mice.
- Immobilization: a 2024 study reported that MOTS-c reduced immobilization-induced muscle atrophy in mice, partly by limiting fat infiltration into the muscle.
These findings matter for a modern question: whether compounds like MOTS-c could help preserve muscle during GLP-1-driven weight loss, a problem we cover in Muscle loss on GLP-1 drugs. For now, that remains a hypothesis.
A human genetic clue: the K14Q variant
One of the more interesting human data points doesn’t involve giving anyone MOTS-c at all. A variant in mitochondrial DNA (m.1382A>C) changes the 14th amino acid of MOTS-c from lysine to glutamine (K14Q). The variant is found mainly in Northeast Asian populations.
Japanese studies have linked K14Q to differences in muscle fibre composition and muscular performance, and the variant appears to produce a less active form of the peptide. It’s a natural experiment suggesting that MOTS-c activity matters in human muscle, though the effect sizes are modest and the findings come from a limited number of cohorts.
MOTS-c, insulin resistance and type 2 diabetes
The original 2015 paper was framed around insulin resistance, and that remains the most clinically relevant thread. The logic is simple: skeletal muscle is the body’s largest consumer of glucose after a meal, insulin resistance in muscle is an early step toward type 2 diabetes, and MOTS-c increases muscle glucose uptake through AMPK, a pathway that works partly independently of insulin. Exercise also increases glucose uptake through AMPK, which is one reason physical activity improves blood sugar even in people with insulin resistance.
Several observational studies have reported lower circulating MOTS-c in people with obesity, insulin resistance or type 2 diabetes, but the findings are not consistent across cohorts, and low levels could be a consequence of metabolic disease rather than a cause. No study has yet tested whether giving MOTS-c improves blood sugar control in people with diabetes. Metformin, the most widely used diabetes drug, also acts partly through AMPK, which makes it a natural comparison compound in laboratory work.
Measuring MOTS-c: why studies disagree
If you read the human literature on MOTS-c levels, you’ll find conflicting results: levels that fall with age in one study and not in another, or that are lower in diabetes in one cohort and unchanged in the next. Much of this comes down to measurement.
- Assays vary. Most studies use commercial ELISA kits, which differ in the antibodies they use and haven’t been standardized against each other.
- Small peptides are hard to measure. Short peptides at low concentrations in blood are prone to degradation and to binding other proteins, which affects what an assay detects.
- Levels change quickly. Exercise raises MOTS-c within hours, so the timing of a blood draw relative to activity matters.
- Blood isn’t muscle. MOTS-c may act mainly within muscle, so blood levels may only loosely reflect its activity.
Mass spectrometry-based methods, which identify the peptide directly, would help resolve some of these disagreements. For researchers, it’s a reminder to treat single-cohort association studies cautiously.
What’s been tested in humans
Here the honest summary is short. Human MOTS-c data falls into three categories:
| Type of evidence | What it shows | Limit |
|---|---|---|
| Measured MOTS-c levels | Levels rise with exercise; some studies report lower levels with age, obesity or diabetes | Association only; assays vary between labs |
| Genetic variant (K14Q) | Linked to muscle traits in Japanese cohorts | Small effects; limited populations |
| Analogue trial (CB4211) | Small early-phase signals in liver fat and glucose | Not MOTS-c itself; not advanced |
There are no published randomized controlled trials of MOTS-c itself in humans for weight, metabolism, aging or performance.
CB4211: the drug that tried to bring MOTS-c to the clinic
CohBar, a biotech company co-founded by Pinchas Cohen and others in the MDP field, developed CB4211, a modified analogue of MOTS-c designed to be more stable and drug-like, aimed at fatty liver disease (NASH) and obesity.
In August 2021, CohBar reported topline results from a phase 1a/1b study. In participants with obesity and fatty liver, CB4211 produced reductions in liver fat and in some markers of liver injury and blood glucose compared with placebo over a short treatment period. Injection-site reactions were the most common side effect. The study was small and short.
CohBar did not advance CB4211 into larger trials. That is not evidence that the approach failed; small biotechs stop programs for financial reasons all the time. But it does mean the most advanced attempt to turn MOTS-c biology into a drug stalled at an early stage.
Evidence summary: what’s solid and what isn’t
| Claim | Strength of evidence |
|---|---|
| MOTS-c exists and is encoded in mitochondrial DNA | Strong |
| It activates AMPK and acts on skeletal muscle | Strong in cells and mice |
| Exercise raises MOTS-c in humans | Moderate (small human studies) |
| It prevents diet-induced obesity and insulin resistance | Mice only |
| It improves physical function in old age | Mice only |
| It causes weight loss in people | No evidence |
| It extends human lifespan or healthspan | No evidence |
Safety: what is and isn’t known
Because there are no published human trials of MOTS-c itself, there is no proper human safety profile. What can be said:
- The CB4211 analogue was reasonably tolerated over a short period in a small study, with injection-site reactions most common.
- Mouse studies have not reported major toxicity at the doses tested.
- Long-term effects of raising MOTS-c above natural levels in humans are unknown.
- As with any research peptide, product quality (identity, purity, sterility) is the most immediate real-world risk, which is the focus of Health Canada’s April 2026 advisory against injecting peptides bought online.
More detail in MOTS-c side effects.
The July 2026 FDA vote
On July 23, 2026, the FDA’s Pharmacy Compounding Advisory Committee voted 7–5, with 2 abstentions, to recommend adding MOTS-c to the list of bulk substances that US pharmacists may use for compounding. FDA’s own review staff had recommended against it.
Three points keep this in proportion. The vote is advisory, and FDA will decide through rulemaking. Being compoundable would not make MOTS-c an approved drug. And it’s a US process, with no direct effect on its status in Canada, where MOTS-c is not an authorized drug. The same meeting also voted on BPC-157, TB-500, KPV, epitalon, semax and DSIP; see Peptides for healing for the full table.
WADA: banned in sport since 2025
MOTS-c was added by name to the WADA Prohibited List that took effect on January 1, 2025, as an example of an AMPK activator under section S4 (hormone and metabolic modulators). It is prohibited at all times, in and out of competition. Athletes subject to anti-doping rules should treat it like any other banned metabolic modulator.
MOTS-c vs SS-31, humanin and NAD+
MOTS-c is often lumped in with other “mitochondrial” compounds. They work in very different ways.
| MOTS-c | SS-31 (elamipretide) | Humanin | NAD+ | |
|---|---|---|---|---|
| What it is | Mitochondrial-encoded peptide hormone | Synthetic peptide that binds cardiolipin | Mitochondrial-encoded peptide | Coenzyme (not a peptide) |
| Where it acts | Signals to muscle and nucleus | Inner mitochondrial membrane | Cell-surface receptors | Inside cells, many enzymes |
| Main research area | Metabolism, exercise, aging | Mitochondrial disease, heart | Neuroprotection, aging | Aging, metabolism |
| Human status | No published trials of MOTS-c itself | FDA-approved 2025 (Barth syndrome) | No trials | Small trials, mixed results |
Full comparison: Mitochondrial peptides: MOTS-c and SS-31, SS-31 (elamipretide) and NAD+ injection side effects.
Four myths about MOTS-c
“It’s exercise in a vial.”
It reproduces some metabolic effects of exercise in mice. Exercise also strengthens the heart, bones and brain, improves mood and sleep, and builds muscle through mechanical loading, none of which MOTS-c has been shown to replicate.
“It’s a proven fat burner.”
It prevented weight gain in mice on a high-fat diet. That is not the same as causing weight loss, and there is no human weight-loss trial.
“It reverses aging.”
It improved physical capacity in old mice. Healthspan measures in mice are encouraging, but no human aging trial exists.
“The FDA approved it in 2026.”
An advisory committee voted to recommend it for the US compounding list. That is neither drug approval nor a final FDA decision.
For researchers
MOTS-c is a useful tool for several kinds of laboratory work:
- AMPK activation and glucose uptake assays in skeletal muscle cell lines (such as C2C12 myotubes).
- Comparisons with AICAR and other AMPK activators to separate MOTS-c-specific effects from general AMPK effects.
- Nuclear translocation and gene-expression studies under metabolic or oxidative stress.
- Muscle atrophy models, including combinations with incretin compounds in metabolic research.
Practical points: MOTS-c is a short peptide with several hydrophobic and positively charged residues, so solubility and adsorption to plastic can affect results at low concentrations. Batch identity by mass spectrometry and purity by HPLC should be confirmed; see How to read a peptide COA. TrueLabs supplies MOTS-c from $55, with batch COAs in the COA library.
FAQ
Tap a question to reveal the answer.
What does MOTS-c do?
MOTS-c is a peptide encoded in mitochondrial DNA that acts mainly on skeletal muscle. It activates AMPK, the cell’s energy sensor, increasing glucose uptake and fat burning. In mice it prevented diet-induced obesity and improved physical performance, including in old age.
Is MOTS-c proven to work in humans?
No. There are no published randomized trials of MOTS-c itself in humans. Human evidence is limited to measurements showing exercise raises MOTS-c levels, a genetic variant linked to muscle traits, and a small early trial of an analogue, CB4211.
Does MOTS-c help with weight loss?
It prevented weight gain in mice on a high-fat diet, but it has not been tested for weight loss in controlled human trials.
Why is MOTS-c called an exercise mimetic?
Exercise raises MOTS-c levels in human muscle and blood, and in mice MOTS-c reproduces some metabolic effects of exercise, including increased running capacity. It does not reproduce the full range of exercise benefits.
Is MOTS-c legal in Canada?
MOTS-c is not an approved drug in Canada. It is sold legally as a research reagent for laboratory use, without health claims. Health Canada has warned against injecting peptides bought online.
Is MOTS-c banned by WADA?
Yes. Since January 1, 2025, MOTS-c has been named on the WADA Prohibited List under section S4 as an AMPK activator, prohibited at all times.
Did the FDA approve MOTS-c?
No. In July 2026, an FDA advisory committee voted 7–5 to recommend adding MOTS-c to the US compounding bulks list. That is a non-binding recommendation about pharmacy compounding, not drug approval.
What is the difference between MOTS-c and SS-31?
MOTS-c is a natural peptide hormone encoded in mitochondrial DNA that signals to muscle and the nucleus. SS-31 is a synthetic peptide that binds cardiolipin in the inner mitochondrial membrane. SS-31 (elamipretide) was approved by the FDA in 2025 for Barth syndrome; MOTS-c has no approval.
Does exercise increase MOTS-c naturally?
Yes. In a 2021 study, a single exercise session raised MOTS-c in human skeletal muscle about 12-fold and increased blood levels, which then returned toward baseline after rest.
Related reading
- MOTS-c side effects
- Mitochondrial peptides: MOTS-c and SS-31
- Longevity peptides
- Peptides for weight loss
- What is tesamorelin?
References
- Lee C, Zeng J, Drew BG, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab. 2015;21(3):443–454. PubMed
- 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 Metab. 2018;28:516–524. PubMed
- Reynolds JC, Lai RW, Woodhead JST, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun. 2021;12:470. PubMed
- Kumagai H, et al. MOTS-c reduces myostatin and muscle atrophy signaling. Am J Physiol Endocrinol Metab. 2021;320:E680–E690. PubMed
- Kumagai H, et al. The MOTS-c K14Q polymorphism in the mtDNA is associated with muscle fiber composition and muscular performance. Biochim Biophys Acta Gen Subj. 2022;1866:130048. PubMed
- Kumagai H, et al. Mitochondrial-derived microprotein MOTS-c attenuates immobilization-induced skeletal muscle atrophy by suppressing lipid infiltration. Am J Physiol Endocrinol Metab. 2024;326:E207–E214. PubMed
- Kumagai H, et al. MOTS-c modulates skeletal muscle function by directly binding and activating CK2. iScience. 2024;27:111212. PubMed
- CohBar. Positive topline results from the phase 1a/1b study of CB4211. August 10, 2021. BioSpace
- The FDA Law Blog. PCAC approves four bulk drug substances for the 503A list. July 2026. FDA Law Blog
- Sport Integrity Australia. 2025 Prohibited List changes (MOTS-c). Sport Integrity Australia
- Health Canada. Think twice before injecting peptides bought online. Public advisory, April 9, 2026. Health Canada
This article summarizes published research for information only and is not medical advice. TrueLabs research compounds are sold for in vitro and laboratory research use only and are not intended for human or veterinary use.