Is MOTS-c really exercise in a pill?

What MOTS-c is

MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA, inside the gene for the 12S ribosomal RNA. Its discovery paper, published in 2015, reported that it acts mainly on skeletal muscle. It interferes with the folate cycle and purine synthesis, which in turn activates AMPK, a cellular energy sensor that exercise also switches on.

In the same paper, treating mice with MOTS-c prevented insulin resistance caused by aging and by a high-fat diet, and also prevented diet-induced obesity. These findings are why the peptide is often described as metabolic. They are mouse results.

Sources: PubMed 25738459

Where the "exercise" idea comes from

A 2021 study reported that MOTS-c improved physical performance in young (2 months), middle-aged (12 months) and old (22 months) mice. Intermittent treatment started late in life (23.5 months) increased physical capacity and healthspan measures in mice. The same paper reported that in humans, exercise increases the body's own MOTS-c in skeletal muscle and in the blood.

A 2022 rodent study found that 4-8 weeks of voluntary running raised MOTS-c protein in several leg muscles about 1.5- to 5-fold. A single injection in untrained mice increased running time by 12% and distance by 15% in one exercise test. So the evidence shows that exercise raises MOTS-c and that extra MOTS-c helps mice run. It does not show that MOTS-c can replace exercise.

Sources: PubMed 33473109 · PubMed 35808870

What human studies show

Published human studies have measured natural MOTS-c levels, not the effects of taking it. In a 2021 randomized study, 30 people were assigned to endurance exercise, resistance exercise or no exercise (10 per group). Circulating MOTS-c only showed a trend toward an increase after endurance exercise. Resting levels of mitochondrial-derived peptides were not related to aerobic fitness, leg strength or muscle mitochondrial DNA.

A 2023 preliminary study of 20 physically active adults found that higher resting serum MOTS-c went with more jump power, force and muscle mass, but not with peak oxygen uptake, the standard measure of aerobic fitness. Correlations like these cannot show that MOTS-c causes fitness, and the results do not line up neatly with the idea of an endurance-exercise mimic.

Sources: PubMed 34351816 · PubMed 37834399

Why "exercise in a pill" overreaches

Exercise affects the heart, blood vessels, brain, bones and immune system, not just muscle metabolism. One signalling peptide that touches part of that response in mice is not a substitute. A 2023 review noted that no effective method of using MOTS-c in the clinic has been developed. The FDA states that it has not identified any human exposure data on drug products containing MOTS-c by any route.

The first placebo-controlled efficacy test is now under way. ClinicalTrials.gov lists a randomized, double-blind Phase 2 trial of MOTS-c in adults with prediabetes and overweight or obesity (estimated 120 participants, recruiting). Its primary outcomes are insulin sensitivity and adverse events. Even a positive result there would address blood sugar control, not the full range of exercise benefits.

Sources: PubMed 36761202 · fda.gov · clinicaltrials.gov

Safety and regulatory context

MOTS-c is not FDA approved for any use. The FDA lists it among compounding substances whose category 2 nominations were withdrawn. It describes a significant risk of immune reactions for certain routes and complexities with impurities and characterization. It also says the agency lacks important information about whether MOTS-c would cause harm in humans.

On July 23, 2026, the FDA's Pharmacy Compounding Advisory Committee voted to recommend adding MOTS-c to the 503A bulks list for obesity and osteoporosis. News reports gave the tally as 7-5. FDA staff had recommended against listing the peptides on the agenda, citing a lack of clinical evidence of safety and efficacy. The vote is advisory and is not an approval. A 2026 sports-medicine review cautioned that many unapproved peptides look good in animals while rigorous human safety data remain scarce.

Sources: fda.gov · statnews.com · PubMed 41966639

Profiles

MOTS-c profile →

References

1. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab · 2015 · PMID 25738459
2. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun · 2021 · PMID 33473109
3. MOTS-c increases in skeletal muscle following long-term physical activity and improves acute exercise performance after a single dose. Physiol Rep · 2022 · PMID 35808870
4. Acute endurance exercise stimulates circulating levels of mitochondrial-derived peptides in humans. J Appl Physiol (1985) · 2021 · PMID 34351816
5. MOTS-c Serum Concentration Positively Correlates with Lower-Body Muscle Strength and Is Not Related to Maximal Oxygen Uptake-A Preliminary Study. Int J Mol Sci · 2023 · PMID 37834399
6. MOTS-c: A promising mitochondrial-derived peptide for therapeutic exploitation. Front Endocrinol (Lausanne) · 2023 · PMID 36761202
7. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med · 2026 · PMID 41966639

Other sources

• https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
• https://clinicaltrials.gov/study/NCT07505745
• https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
• https://www.statnews.com/2026/07/24/fda-peptide-compounding-panel-backs-epitalon-rejects-emideltide/

These are original summaries of published research, written with AI assistance and checked against the cited sources. They are not medical advice and have not been reviewed by a clinician. Every PubMed reference was checked against PubMed's record for title, year and journal. All claim checks · Editorial standards