Reader’s guide · First edition · September 2026 · Revised September 23, 2026
MOTS-c
A guide to the mitochondrial peptide: an exercise mimic in mice, a discontinued analog in twenty people, and a July 2026 committee vote the FDA's own staff argued against
MOTS-c is a sixteen-amino-acid peptide encoded not by the cell's main genome but by the small genome inside its mitochondria, discovered in 2015. In mice it improves insulin sensitivity, prevents diet-induced obesity, and restores the running capacity of old animals, and in people it rises in the blood with exercise. Sellers call it the exercise peptide. This guide covers what it does in animals, what the single human program (a modified analog, twenty people, four weeks, then abandoned) showed, why no study has ever given MOTS-c itself to a person, how the vials are dosed, and what the FDA's advisory committee decided in July 2026 over the objection of the agency's reviewers.
Who this is for
Written for adults who are using, or being offered, MOTS-c for metabolic health, fat loss, endurance, or aging, and for the clinics and sellers describing it. It summarizes the published record and the regulatory position as of the edition date. It is not medical advice.
Mitochondria carry their own tiny genome, long thought to encode only the machinery of respiration. In 2015 a group at the University of Southern California reported that a short reading frame inside the 12S ribosomal RNA gene produces a sixteen-amino-acid peptide, which they named MOTS-c. It acts as a metabolic signal: under stress it moves to the nucleus and switches on genes that improve glucose handling, and it activates AMPK, the same energy sensor exercise and metformin engage.
- Class
- Mitochondrial-derived peptide, 16 amino acids; discovered 2015; the body makes it and blood levels rise with exercise
- Claimed uses
- Insulin sensitivity, fat loss, endurance, muscle preservation, longevity; nominated to FDA for obesity and osteoporosis
- Human evidence
- None for MOTS-c itself. One 2021 Phase 1a/1b trial of a modified analog, CB4211, in 20 adults for four weeks; the company then abandoned it
- Forms
- Research-chemical vials of 10 and 40 mg; no approved or compounded product
- Price as sold
- $30 to $50 for 10 mg; $55 to $130 for 40 mg; a common seller protocol uses 40 to 60 mg a month
- Status
- Not approved. FDA's advisory committee voted 7 to 5 in July 2026 to recommend it for the 503A compounding list, against FDA staff's recommendation; the agency has not acted
- Anti-doping
- Prohibited at all times as a non-approved substance (S0)
The exercise peptide
In a 2021 study of ten young men, MOTS-c in muscle and blood rose with a bout of exercise and returned to baseline afterward. That is the origin of the name. It is evidence that the body uses the peptide, not that injecting it does what exercise does.
The animal literature is the whole case. The human literature is one company's trial of a different molecule, ended by the company itself. FDA's reviewers wrote in July 2026 that they found no clinical study of MOTS-c in people, for safety or effectiveness, by any route.
| Study | What was done | What it showed | Grade |
|---|---|---|---|
| Lee et al., 2015 (mice) | Daily injections in mice on a high-fat diet | Prevented obesity and insulin resistance; improved glucose handling | Animal |
| Reynolds et al., 2021 (mice and 10 men) | Late-life treatment of old mice; exercise study in young men | Old mice ran longer and kept muscle; MOTS-c rose in human muscle and blood with exercise | Animal, plus a human observation |
| Kim et al., 2019 (mice) | Clamp studies | Improved insulin-stimulated glucose disposal in muscle by about 30 percent | Animal |
| CB4211 Phase 1a/1b, 2021 (20 people) | A modified analog, four weeks, randomized and placebo-controlled, in obese adults with fatty liver | Lower liver enzymes and glucose; a trend to lower weight; injection-site reactions in more than one in ten | C, for a different molecule |
| MOTS-MET Phase 2a (recruiting, NCT07505745) | 120 adults with prediabetes, 12 weeks of subcutaneous MOTS-c against placebo | Began February 2026; primary completion estimated February 2027 | Pending |
CB4211 is not MOTS-c: it is an engineered analog the company chose because the native peptide was not suitable as a drug. In 2022 CohBar reported the formulation was not suitable for further development and sought a merger; the program ended.
Published human trials of MOTS-c itself, by any route, as of FDA's July 2026 review
People in the only controlled trial of a related molecule, for four weeks
What would count as evidence
The registered Phase 2a would be the first: twelve weeks of the actual peptide against placebo with a glucose tolerance test as the endpoint. Until it reads out, every metabolic, endurance, and longevity claim for a MOTS-c vial rests on mice.
| Form | Instruction | What is known |
|---|---|---|
| Vial, 10 mg | 5 mg two or three times weekly, or 10 mg once weekly, subcutaneous, in 4 to 8 week cycles | No human dose has ever been studied; the numbers are scaled by sellers from mouse doses |
| Vial, 40 mg | As above, at a lower price per milligram | As above |
| Stacks | With NAD+, epitalon, SS-31, or a GLP-1 | Nothing on the combination |
What the next table is, and is not
It expresses the common seller protocol for a 10 mg vial so the arithmetic can be checked. No human dose of MOTS-c exists; the mouse doses were milligrams per kilogram, and the seller protocols are not derived from them by any published method. A vial's identity, strength, and sterility are unverified.
- Vial
- 10 mg lyophilized MOTS-c, as sold
- Water added
- 1 mL bacteriostatic water
- Concentration
- 10 mg/mL. One concentration for the whole vial.
- Syringe
- 1 mL U-100 insulin syringe; the doses are milligrams and the draws are large
| Weeks | Dose | Draw | Units | Used per 4 weeks |
|---|---|---|---|---|
| 1–2 | 5 mg, twice a week | 0.5 mL | 50 | 20 mg (2 vials) |
| 3–8 | 5 mg, three times a week | 0.5 mL | 50 | 60 mg (6 vials) |
| Alternative | 10 mg, once a week | 1 mL | 100 | 40 mg (4 vials) |
At vendor prices a month on the three-times-weekly protocol is $200 to $270 in vials. Sellers suggest a break after 8 weeks; there is no pharmacology behind either the cycle or the break.
What each draw looks like · 1 mL (100-unit) U-100 insulin syringe
The plunger tip sits on the line for the dose. Units are marks on a U-100 syringe: 100 units is 1 mL. The picture assumes the concentration in the table above; a different amount of water changes every line.
MOTS-c was one of seven peptides FDA's Pharmacy Compounding Advisory Committee took up on July 23 and 24, 2026, nominated for the 503A bulks list for obesity and osteoporosis. FDA's briefing document recommended against it on three grounds: the substance is not well enough characterized for compounding, there is little or no human evidence of effectiveness by the proposed routes, and there is no human safety data, including on immunogenicity. The committee voted 7 to 5, with two abstentions, to recommend it anyway, alongside BPC-157, TB-500, KPV, epitalon, and Semax.
| Question | Answer |
|---|---|
| Is MOTS-c approved? | No, and the vote is not an approval |
| Can a pharmacy compound it now? | No. The committee advises; FDA decides by rulemaking, which has not happened |
| Is the research vial now legal to use? | No. It remains an unapproved new drug |
| What did FDA's own scientists say? | That there were no clinical studies of safety or effectiveness in people, and no animal safety data to inform the proposed uses |
| What did the committee weigh instead? | Public testimony and the animal record; commentators called it a compounding back door for unapproved peptides |
Reading the headline
Sellers report the vote as FDA clearing MOTS-c. The record says the opposite: the agency's reviewers found no human evidence at all, and an advisory panel recommended listing it anyway. Whether FDA follows the panel is undecided; if it does, a pharmacy could compound it on a prescription. Nothing about the vial changes either way.
Reading a vial: milligrams and units9
The arithmetic is simple because the doses are whole milligrams. The pitfall is the 40 mg vial, which sellers suggest reconstituting with 2 mL, giving 20 mg/mL: a 5 mg dose becomes 25 units rather than 50.
units = (dose mg ÷ concentration mg/mL) × 100
A 10 mg vial with 1 mL is 10 mg/mL: 5 mg is 0.5 mL, or 50 units. A 40 mg vial with 2 mL is 20 mg/mL: the same 5 mg is 25 units. Write the concentration on the vial.
| Vial and water | Concentration | 5 mg | 10 mg |
|---|---|---|---|
| 10 mg + 1 mL | 10 mg/mL | 50 units | 100 units |
| 10 mg + 2 mL | 5 mg/mL | 100 units | Two syringes |
| 40 mg + 2 mL | 20 mg/mL | 25 units | 50 units |
Refrigerate after reconstitution. The peptide's stability in bacteriostatic water over weeks has not been published.
- Reported
- For the analog CB4211, injection-site reactions in more than one in ten, transient and mild to moderate; no serious adverse events in four weeks. Seller forums report the same site reactions with MOTS-c, with occasional nausea and fatigue.
- Immunogenicity
- Unassessed. FDA raised it specifically: a foreign-made peptide that is also a natural human signal could provoke antibodies that neutralize the body's own MOTS-c. No one has looked.
- Metabolic
- A peptide that improves insulin sensitivity in mice could lower blood sugar in a person on insulin or a sulfonylurea; unstudied.
- Who should not
- Pregnancy, anyone under 18, and anyone with cancer or a cancer history, because a peptide that reprograms cell metabolism under stress has not been tested in any of them.
- Product
- Research-chemical purity varies by lot; independent testing of gray-market peptides has found underfilled and mislabeled vials across the category.
- Unknown
- Everything past four weeks, for a molecule that is not the one sold.
- What am I trying to change, and would exercise, which raises my own MOTS-c, do it with evidence?
- Do I understand that no person has ever received MOTS-c in a published trial?
- Do I take insulin or a sulfonylurea, or have a cancer history?
- What is the concentration on this vial, and my dose in units?
- Where did the vial come from, and is there an independent certificate of analysis for this lot?
- Am I tested for anti-doping? MOTS-c is prohibited at all times.
- Has the Phase 2a trial reported yet? If not, what am I basing this on?
What does have evidence for what MOTS-c is sold for
Aerobic and resistance exercise for insulin sensitivity, endurance, and muscle in older adults; metformin and the GLP-1 drugs for glucose and weight; each with outcome trials. MOTS-c is a real biological signal with a mouse literature and no human one.
Latest
Developments since this edition, newest first. Items here are dated and sourced; they update the guide without re-editing it.
FDA warning letters reject the 'research use only' label at five vendors
Letters dated August 24 to five online peptide sellers, including a major MOTS-c vendor, say research-only labeling does not change a product's status as an unapproved drug when the site's dosing guidance and bundled bacteriostatic water show human use. MOTS-c itself was not among the named products.
Compounding consultants: the July vote changed nothing yet
A regulatory note restates the 7 to 5 tally with two abstentions and stresses that pharmacies may not begin compounding MOTS-c until FDA completes notice-and-comment rulemaking. The next peptide meeting, covering GHK-Cu, LL-37, Melanotan II, dihexa, and PEG-MGF, is due before the end of February 2027.
Law firm: rulemaking on the six peptides may run into 2027
A summary of the meeting notes FDA staff opposed all seven nominated peptides and that adding any of them requires a proposed and final rule; an interim placement by the HHS secretary is possible but has not been announced.
First trial of MOTS-c itself is recruiting, with results due 2027
The Phase 2a MOTS-MET study (NCT07505745) of 120 adults with prediabetes began enrolling in February 2026 with primary completion estimated for February 2027. No results are posted; every claim for the vial still rests on animal data.
References
- 1.Lee C, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab. 2015;21(3):443-454.
- 2.Reynolds JC, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun. 2021;12:470.
- 3.Kim SJ, et al. The mitochondrial-derived peptide MOTS-c is a regulator of plasma metabolites and enhances insulin sensitivity. Physiol Rep. 2019;7(13):e14171.
- 4.CohBar, Inc. CohBar announces positive topline results from the Phase 1a/1b study of CB4211 under development for NASH and obesity. Press release, August 10, 2021. https://www.globenewswire.com/news-release/2021/08/10/2278324/0/en/CohBar-Announces-Positive-Topline-Results-from-the-Phase-1a-1b-Study-of-CB4211-Under-Development-for-NASH-and-Obesity.html
- 5.CohBar, Inc. Form 8-K, 2022 (CB4211 formulation not suitable for further development; strategic alternatives), and merger agreement with Morphogenesis, Inc., May 22, 2023. https://www.sec.gov/Archives/edgar/data/1522602/000121390022015831/ea155693ex99-1_cohbar.htm
- 6.U.S. Food and Drug Administration. Briefing document, Pharmacy Compounding Advisory Committee meeting, July 23-24, 2026: MOTS-c. https://www.fda.gov/media/193347/download
- 7.U.S. Food and Drug Administration. July 23-24, 2026 meeting of the Pharmacy Compounding Advisory Committee (agenda, materials, and vote summary). https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
- 8.MOTS-c for improving insulin sensitivity in adults with prediabetes and overweight/obesity (MOTS-MET), Phase 2a. Clinical trial registration, 2026. https://ctv.veeva.com/study/mots-c-for-improving-insulin-sensitivity-in-adults-with-prediabetes-and-overweight-obesity
- 9.Representative research-chemical MOTS-c listings (10 and 40 mg) and seller protocol pages, as sold September 2026.
- 10.Health Affairs Forefront. FDA advisory committee's vote may open a drug-compounding back door for unapproved peptides. 2026. https://www.healthaffairs.org/content/forefront/fda-advisory-committee-s-vote-may-open-drug-compounding-back-door-unapproved-peptides