# MOTS-c FAQ: Frequently Asked Questions — Answered from the Literature > MOTS-c frequently asked questions: mechanism, dosage, WADA status, side effects, humanin comparison, aging, and clinical trial status. Answers drawn from peer-reviewed sources. ## What does the MOTS-c peptide do? MOTS-c activates AMPK via the folate-purine-AICAR axis, enhancing glucose uptake in skeletal muscle via GLUT4 translocation and promoting fatty acid beta-oxidation. Under metabolic stress it translocates to the nucleus, binding NRF2 to upregulate antioxidant genes. A 2024 study identified CK2alpha as a direct binding partner [12]. Primary tissue targets are skeletal muscle, liver, and adipose [1][4][17]. ## What is the MOTS-c peptide? A 16-amino-acid peptide (sequence: MRWQEMGYIFYPRKLR) encoded by a short open reading frame within the mitochondrial 12S rRNA gene (MT-RNR1). Molecular weight 2174.6 Da, highly conserved across 14 species. One of the first peptide hormones known to be encoded by the mitochondrial genome rather than the nuclear genome [1]. ## Is MOTS-c an exercise mimetic? Mouse studies show exogenous MOTS-c increases treadmill running capacity and recapitulates AMPK-driven metabolic reprogramming similar to exercise [2]. Human exercise induces an 11.9-fold increase in skeletal muscle MOTS-c expression and a 1.5-fold rise in circulating MOTS-c [3]. Whether exogenous administration fully replicates exercise-training adaptations in humans is not established. ## Is MOTS-c banned in sports? Yes. MOTS-c is prohibited at all times under WADA S4.4.1 (Activators of AMP-activated protein kinase / Metabolic Modulators). USADA confirms MOTS-c has no approved medical use and no TUE pathway. Note: the correct category is S4.4.1, not S2. ## What are the downsides of MOTS-c? USADA-documented self-experiment reports include palpitations, injection-site reactions, insomnia, fatigue, and fever. The key mechanistic concern is folate-pathway disruption [17]. Long-term safety in humans has not been characterized. No Phase 2/3 safety trial data exist. ## What are the main MOTS-c peptide benefits? Published interventional literature (rodent models) reports: improved insulin sensitivity and reduced adiposity [1]; twofold increase in treadmill running distance in middle-aged and old mice [2]; prevention of glucocorticoid-induced atrophy in human myotubes in vitro [13]; improved cardiac function in pressure-overload mouse model [10]; restored mitochondrial respiration in diabetic rat heart [11]. Human interventional data are absent. ## Does MOTS-c decline with age? Yes, in humans. Circulating MOTS-c in 45–55-year-olds is 11% lower than in 18–30-year-olds; in 70–81-year-olds it is 21% lower [6]. Skeletal muscle MOTS-c expression is approximately 1.5-fold higher in older versus younger men, suggesting compensatory tissue upregulation [6]. ## Does MOTS-c extend longevity? Intermittent MOTS-c treatment (5 mg/kg 3×/week subcutaneous) produced a trend toward 6.4% extended median lifespan in aged male mice — a trend, not a statistically significant result [2]. The K14Q variant meta-analysis (27,527 subjects) found no longevity association in 736 Japanese centenarians [9]. ## Are there human clinical trials for MOTS-c? No completed Phase 2 or Phase 3 clinical trials for the native MOTS-c sequence have been published as of 2025. Available human data are observational [6][7][8] and exercise-induced endogenous response studies [3]. CB-4211, a MOTS-c analog for obesity, entered early human trials but Phase 2 results have not been published. ## Can you take MOTS-c with metformin? Both activate AMPK — metformin via Complex I inhibition, MOTS-c via folate-AICAR accumulation [1][17]. The combination is theoretically additive but potentially redundant, and could increase the risk of excessive AMPK activation. No controlled human study has examined the combination. ## References [1] Lee C, et al. Cell Metabolism. 2015;21(3):443-454. DOI: 10.1016/j.cmet.2015.02.009 PMID: 25738459 [2] Reynolds JC, et al. Nature Communications. 2021;12(1):773. DOI: 10.1038/s41467-020-20790-0 PMID: 33473109 [3] Reynolds JC, et al. [Human exercise data.] Nature Communications. 2021;12(1):773. PMID: 33473109 [4] Kim KH, et al. Cell Metabolism. 2018;28(3):516-524. DOI: 10.1016/j.cmet.2018.06.008 PMID: 29983246 [6] D'Souza RF, et al. Aging (Albany NY). 2020;12(5):5044-5065. DOI: 10.18632/aging.102944 PMID: 32182209 [7] Du C, et al. Pediatric Diabetes. 2018;19(5):1058-1064. DOI: 10.1111/pedi.12685 PMID: 29691953 [8] Luo YH, et al. Diabetes, Metabolic Syndrome and Obesity. 2023;16:1125-1133. DOI: 10.2147/DMSO.S403934 PMID: 37077579 [9] Zempo H, et al. Aging (Albany NY). 2021;13(2):1801-1817. DOI: 10.18632/aging.202529 PMID: 33468709 [10] Zhong P, et al. JCMM. 2022;26(21):5672-5683. DOI: 10.1111/jcmm.17551 PMID: 36156853 [11] Pham T, et al. Front Physiol. 2025;16:1602271. DOI: 10.3389/fphys.2025.1602271 PMID: 40661667 [12] Kumagai H, et al. iScience. 2024;27(11):111212. DOI: 10.1016/j.isci.2024.111212 PMID: 39559755 [13] Elhusseiny R, et al. Physiological Reports. 2026;14(4):e70791. DOI: 10.14814/phy2.70791 PMID: 41732124 [17] Wan W, et al. J Transl Med. 2023;21(1):36. DOI: 10.1186/s12967-023-03885-2 PMID: 36670507 [18] Cobb LJ, et al. Aging (Albany NY). 2016;8(4):796-809. DOI: 10.18632/aging.100943 PMID: 27070352 --- Calibrated from the peer-reviewed record — a machined-instrument digest of the MOTS-c literature, not a clinic, not a vendor, not a prescription.