MOTS-c

MOTS-c stands for mitochondrial open reading frame of the 12S ribosomal RNA type-c, which is a long way of saying that it is a short chain of 16 amino acids whose instructions sit inside the tiny separate genome carried by your mitochondria, the compartments in each cell that turn food into usable energy. It was first sequenced in 2015 by Changhan Lee and colleagues at the University of Southern California, which makes it one of the newest molecules sold in the peptide market. Your body already makes it: it turns up in skeletal muscle, heart and brain tissue and circulates in the blood, and published work reports that blood levels fall as people get older. Everything sold as injectable MOTS-c is a synthetic copy of that natural sequence. The important thing to understand before anything else is the gap between the science and the product: when the US Food and Drug Administration reviewed MOTS-c in May 2026, it searched the published literature and stated it could not find a single clinical study or any human exposure data for MOTS-c by any route of administration. Every effect described below comes from mice, rats or cells in a dish.

• Insulin sensitivity and blood-sugar handling, which is the effect the original 2015 mouse work was built around
• Fat loss and resistance to weight gain on a high-fat diet, again a mouse finding
• Endurance and physical capacity, where a single injection improved treadmill performance in young, middle-aged and old mice
• Longevity and healthspan, based on a mouse study in which dosing started at 23.5 months of age and extended median lifespan
• Bone density and vascular calcification, which were among the uses formally nominated to the FDA and which rest on rat and cell-culture data
• Clinics and vendors also market it for mitochondrial energy, metabolic stress resistance and DNA repair, none of which has been measured in a person

Think of your mitochondria as a power station that normally just burns whatever fuel the rest of the body sends it. What the 2015 work suggested is that the power station also writes notes. MOTS-c is one of those notes, and in mice it reaches the muscle and the cell nucleus and effectively says: fuel is tight, switch to burning fat, stop building things you do not need right now. That is the same message a hard training session sends, which is why it gets called an exercise mimetic. The catch is that nobody has shown the note still reads the same way when you inject it under the skin of a human.

1. First doseNo human timeline exists, because no published study has given MOTS-c to a person. In mice, a single 5 mg/kg intraperitoneal injection improved treadmill running within the same session at 2, 12 and 22 months of age (Reynolds et al., 2021). A laboratory study found that MOTS-c added to human whole blood was broken down rapidly into shorter fragments, which raises the open question of how long an injected dose would survive in circulation at all (Knoop et al., 2019).
2. Week 1-2Nothing is published for this window in humans. In mice made obese on a high-fat diet, three days of dosing twice daily cut blood glucose by roughly half, and seven days of dosing restored insulin sensitivity in the soleus muscle of 12-month-old mice to the level of 3-month-old mice (Lee et al., 2015; Kim et al., 2019, as summarised in the FDA evaluation).
3. Week 4-6This is where the cheatsheet cycle ends. The nearest published parallel is eight weeks of daily 0.5 mg/kg injections in high-fat-fed mice, which ended about 20 percent lighter than untreated mice with less liver fat and higher energy expenditure (Lee et al., 2015). Per kilogram of body weight that mouse dose is several times larger than a 5 mg dose in an adult human, and mouse-to-human dose scaling for this peptide has never been worked out.
4. Post-cycleUnknown. There is no published pharmacokinetic study of MOTS-c in any living animal, so how quickly it clears, whether the effect persists, and whether the body's own production adjusts after exogenous dosing have all not been measured.
5. Long termIn mice, intermittent dosing at 15 mg/kg three times a week started at 23.5 months of age raised median lifespan from 912 to 970 days and maximum lifespan from 1047 to 1120 days (Reynolds et al., 2021). No equivalent human observation exists, and the FDA states it found no repeat-dose toxicity, genotoxicity, reproductive or carcinogenicity studies of MOTS-c in any species.

• No adverse events were reported in the studies located, which is not the same as none existing. No study has ever administered MOTS-c to a human, so there is no adverse-event list to report.
• The FDA Office of Surveillance and Epidemiology searched the FDA Adverse Event Reporting System for MOTS-c through March 2025 and retrieved no reports. FDA notes in the same document that compounders operating under section 503A generally do not report adverse events to the agency, so an empty database is weak evidence.
• FDA raised immunogenicity as a specific concern: a 16-amino-acid peptide can provoke an immune response, subcutaneous injection generally carries more immunogenicity risk than intravenous, and one possible consequence is antibodies that neutralise not just the injected peptide but your own endogenous MOTS-c. No study has tested for this.
• Aggregation, peptide-related impurities, endotoxin levels and microbial bioburden for commercially sold MOTS-c were not found in the public literature, and FDA stated it could not rule out the risks associated with them.
• Injection-site reactions, sterility failures and contamination are generic risks of self-injecting a research-grade powder reconstituted at home, and they apply here whatever the molecule does.

• You are pregnant, trying to conceive, or breastfeeding. FDA states it identified no developmental or reproductive toxicity studies of MOTS-c in any species.
• You have a personal history of cancer. No carcinogenicity study of MOTS-c exists, and the molecular target through which it acts is still unidentified, so which tissues it reaches cannot be predicted.
• You take insulin or a sulfonylurea, or otherwise have a real risk of hypoglycaemia. The single most consistent animal finding is a drop in blood glucose, and nobody has measured the size of that effect in a person.
• You have obesity or osteoporosis and are choosing this instead of treatment. FDA pointed out that approved drugs exist for both of the conditions MOTS-c was nominated for.
• You are an athlete subject to drug testing. MOTS-c is named by name on the World Anti-Doping Agency Prohibited List, and a validated mass-spectrometry test for it in plasma has existed since 2019.
• You are a child or adolescent.
• You are not under a physician who can monitor fasting glucose and who knows you are using an unapproved injectable peptide.

• Reading mouse dose numbers as if they transfer. The mouse studies used 0.5 to 15 mg per kilogram of body weight; the cheatsheet figure of 5 mg is a fixed total dose for an adult. Nobody has published the scaling work that would connect the two, so the cheatsheet number is convention, not a calculated equivalent.
• Assuming the injected peptide behaves like the peptide your body makes. Endogenous MOTS-c is produced inside cells; an injected dose has to survive the bloodstream first, and the one relevant laboratory study found it was hydrolysed into shorter fragments quickly in human whole blood.
• Sloppy reconstitution. Use bacteriostatic water, run it down the inside of the vial rather than straight onto the powder, and swirl rather than shake. FDA named aggregation as an unquantified risk for this specific peptide, and rough handling encourages aggregation.
• Storing it wrong. The literature FDA reviewed describes lyophilised MOTS-c as stable below minus 20 degrees Celsius, desiccated and protected from light. A kitchen drawer or a fridge door that opens twenty times a day is not that.
• Stacking it with other glucose-lowering agents, whether that is a GLP-1 drug, metformin or insulin, on the assumption that the effects simply add. No interaction study exists for MOTS-c with anything.
• Treating the pre-workout timing on the cheatsheet as evidence-based. It comes from the exercise-mimetic framing, not from a human dosing study, because there is no human dosing study.