Feeling low on energy is one of those complaints that can mean almost anything. Workouts may feel harder than they used to. Recovery may take longer. You may hit an afternoon wall even after a normal night of sleep, or simply feel that your body is not producing the same level of energy it once did.
If you have started looking into peptides for energy, metabolism or performance, you have probably come across MOTS-c. Online, it is often described as an “exercise peptide” or even an “exercise mimetic.” Those labels are catchy. The biology behind them is more interesting – and more nuanced.
MOTS-c is a peptide encoded within mitochondrial DNA. Researchers are studying how it helps cells respond to metabolic stress, regulate fuel use and adapt to exercise. That makes it more useful to think of MOTS-c as part of the machinery that helps cells manage energy, rather than simply something that “gives you energy.”
Your mitochondria do more than make energy
Most people learn that mitochondria are the “powerhouses of the cell.” That is true: mitochondria help convert nutrients from food into ATP, the molecule cells use as an immediate source of energy.
But mitochondria are also signaling centers. They sense changes in nutrient availability, oxidative stress, physical activity and other forms of cellular stress, then help coordinate how the rest of the cell responds.
One way they appear to do that is through a family of molecules called mitochondrial-derived peptides. MOTS-c is one of them.
So what exactly is MOTS-c?
MOTS-c stands for mitochondrial open reading frame of the 12S rRNA type-c. It is a small peptide made from 16 amino acids and encoded within mitochondrial DNA.
Researchers first described MOTS-c in 2015 while investigating how mitochondria communicate with the rest of the body. What drew attention was its relationship with metabolic homeostasis: the body’s ability to keep glucose use, energy production and other metabolic processes functioning within a healthy range.
A foundational 2015 study involving researchers from the USC Leonard Davis School of Gerontology, UCLA David Geffen School of Medicine and the National Institute on Aging at the NIH found that MOTS-c influenced glucose metabolism and insulin sensitivity, particularly in skeletal muscle.
Since then, scientists have explored its possible roles in cellular energy metabolism, muscle function, exercise adaptation, metabolic stress, aging and mitochondrial signaling.
MOTS-c appears to act like a metabolic messenger
One of the most distinctive findings around MOTS-c is what happens when cells experience stress.
Under conditions such as glucose restriction or oxidative stress, MOTS-c can move from the mitochondria into the cell nucleus, the compartment where most genetic instructions are stored. Once there, it appears to influence the expression of genes involved in helping cells adapt to changing conditions.
In simple terms, mitochondria may be able to detect a metabolic challenge and use MOTS-c as part of the message telling the cell: conditions have changed; adjust how you operate.
This communication from mitochondria back to the nucleus is known as retrograde signaling.
It matters because metabolism is not fixed. Cells continually adjust how they use nutrients and generate energy depending on whether you are eating, fasting, resting, exercising or recovering.
One important pathway: AMPK
Much of the MOTS-c story leads back to AMP-activated protein kinase, or AMPK.
AMPK functions as one of the cell’s energy sensors. When readily available energy falls, AMPK activity rises and shifts metabolism toward processes that help restore ATP. That can include increasing glucose uptake and changing how cells use fats and other fuels.
Exercise is one of the things that activates AMPK. Research suggests MOTS-c can influence this pathway through changes in cellular metabolism, which is one reason scientists became interested in it as a possible bridge between mitochondrial signaling and some of the adaptations associated with exercise.
What does MOTS-c have to do with exercise?
Exercise deliberately places cells under metabolic stress. Muscles suddenly need more energy, oxygen demand changes, fuel use shifts and reactive oxygen species rise temporarily. The body then adapts so it can meet similar demands more effectively in the future.
MOTS-c appears to participate in this response. Human research has found that mitochondrial-derived peptides can change with exercise, although the results vary depending on the type and duration of activity.
Studies have reported changes in circulating MOTS-c after exercise and associations between MOTS-c levels, endurance capacity and mitochondrial function.
A 2026 systematic review of mitochondrial-derived peptides and exercise examined research published between 2016 and 2025 and found that most included studies reported a tendency for mitochondrial-derived peptide levels to increase following physical activity.
That does not mean administering MOTS-c is equivalent to going for a run. It means MOTS-c appears to sit inside some of the same biological territory activated when the body adapts to exercise.
Why do people call it an “exercise mimetic”?
The phrase comes largely from experimental research. In animal models, externally administered MOTS-c has been associated with improved exercise capacity, better metabolic adaptation and increased physical performance.
A widely cited 2021 study published in Nature Communications, led by researchers at the USC Leonard Davis School of Gerontology with collaborators including the University of Auckland, reported improved physical capacity in young, middle-aged and older mice, alongside changes in skeletal muscle metabolism and genes involved in metabolic adaptation.
A 2026 study extended this work along the same biological pathways, including AMPK and PGC-1α, an important regulator of mitochondrial adaptation. It also found lower markers of oxidative stress in the models studied.
A better interpretation of the “exercise mimetic” label is that researchers are studying whether MOTS-c can influence some of the cellular pathways that also respond to physical activity.
And what about energy?
MOTS-c is not caffeine, an energy drink or a conventional stimulant.
What scientists are studying is more fundamental: how cells handle fuel. MOTS-c has been linked with glucose uptake, insulin sensitivity, mitochondrial function and metabolic adaptation in skeletal muscle.
Those processes matter because physical energy ultimately depends, in part, on whether cells can access, process and use fuel effectively. That is very different from temporarily making someone feel more alert.
Why skeletal muscle matters
Skeletal muscle is central to the MOTS-c story. Muscle consumes large amounts of energy during activity and plays a major role in glucose metabolism throughout the body.
Human research has found associations between muscle MOTS-c expression and measures of muscle quality during aging. Mechanistic research has also identified signaling pathways through which MOTS-c may influence muscle glucose uptake and muscle function.
Experimental work continues to investigate whether MOTS-c can help support muscle when metabolic or physiological stress threatens normal function. Together, these findings make skeletal muscle one of the most important areas of current MOTS-c research.
What happens to MOTS-c as we age?
Energy and physical capacity often change with age, and mitochondrial function changes too. MOTS-c may be connected to that process.
Human studies have reported age-related differences in circulating and skeletal muscle MOTS-c levels. Research suggests that the way MOTS-c is regulated may change across tissues as we get older.
This has contributed to wider interest in MOTS-c, healthy aging, metabolic resilience and the maintenance of physical function.
Mitochondrial signaling appears to be one part of the much larger biological story of how the body adapts as we age.
So, can MOTS-c give you more energy?
Many people who routinely inject MOTS-c do report a subjective energy boost. But unlike caffeine or other stimulants, MOTS-c doesn’t provide a nervous or jittery form of energy. Rather, those who benefit from MOTS-c describe the energetic boost as something more stable, smooth, and organic.
That experience is consistent with why MOTS-c is scientifically interesting in the first place: researchers are not primarily studying it as a stimulant. They are studying its role in metabolic stress sensing, skeletal muscle glucose use, communication between mitochondria and the nucleus, exercise adaptation and age-related changes in muscle and metabolic function.
So if you are considering MOTS-c because you feel tired or want better physical performance, the first question should not simply be, “Will MOTS-c boost my energy?” A more useful question is: “Why is my energy or physical capacity lower than I want it to be, and is mitochondrial or metabolic function actually part of that problem?”
Fatigue can have many causes, including sleep, nutrition, training load, iron status, thyroid function, medications, stress and underlying health conditions. A mitochondrial peptide only becomes meaningful when it makes sense within that wider picture.
Where Fitstar comes in
Peptide therapy is about more than choosing a compound.
Fitstar uses your health profile, goals and medical history to build a preliminary peptide protocol that can then be reviewed with a licensed clinician.
When peptide therapy is appropriate and available, Fitstar can help you manage your protocol, track your experience and stay connected with your care team over time.
Because when the goal is better energy, performance or metabolic health, understanding what is driving that goal matters just as much as choosing the peptide.
Sources & Further Reading
Lee C, et al. (2015). The Mitochondrial-Derived Peptide MOTS-c Promotes Metabolic Homeostasis and Reduces Obesity and Insulin Resistance. Cell Metabolism. Foundational research involving USC Leonard Davis School of Gerontology, UCLA David Geffen School of Medicine and the National Institute on Aging at the NIH, identifying MOTS-c and examining its role in skeletal muscle metabolism and metabolic homeostasis. Full text | Journal article
Wan W, et al. (2023). Mitochondria-derived peptide MOTS-c: effects and mechanisms related to stress, metabolism and aging. Journal of Translational Medicine. Review of MOTS-c signaling, AMPK, metabolic stress, exercise and aging. PubMed
Reynolds JC, et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications. Research led by USC Leonard Davis School of Gerontology with international collaborators examining physical capacity, exercise response and skeletal muscle metabolism. Full text - Nature Communications | PMC
von Walden F, et al. (2021). Acute endurance exercise stimulates circulating levels of mitochondrial-derived peptides in humans. Journal of Applied Physiology. Human research examining MOTS-c and other mitochondrial-derived peptides following endurance and resistance exercise. PubMed
Endurance training enhances skeletal muscle mitochondrial respiration by promoting MOTS-c secretion. (2024/2025). Research examining circulating MOTS-c, endurance capacity and mitochondrial respiration in human athletes and experimental models. PubMed
Ayubi N, et al. (2026). Mitochondrial-derived peptides activated by physical exercise as therapeutic targets for metabolic disorders: A systematic review. Physiology International. Systematic review of research published between 2016 and 2025 examining exercise and mitochondrial-derived peptides, including MOTS-c. PubMed | DOI
MOTS-c improves intrinsic muscle mitochondrial bioenergetic health and efficiency in a PGC-1α/AMPK-dependent manner. (2026). Recent mechanistic research into MOTS-c, mitochondrial efficiency, skeletal muscle and oxidative stress. PubMed