“I’m tired all the time.”
I hear some version of this constantly in my practice. Sometimes it’s waking up tired despite getting eight hours of sleep. Sometimes it’s the 3 p.m. crash, brain fog, poor exercise tolerance, or feeling like you simply don’t have the energy you used to have.
When someone tells me they’re tired, I don’t immediately assume they have a “mitochondrial problem.” Fatigue has many possible causes, and we need to think about the basics first: sleep, iron deficiency or anemia, thyroid function, medications, hormonal changes, metabolic health, mood, nutrition, sleep apnea, and other medical conditions.
But I do think about a bigger question:
How well is your body actually making and using energy?
And that’s where mitochondria become really interesting.
Your Body Has to Make Energy All Day, Every Day
You probably remember mitochondria from high school biology as the “powerhouses of the cell.” It’s an overused phrase, but it’s actually a pretty good description.
Mitochondria are tiny structures inside most of our cells. One of their primary jobs is to take the energy contained in the food we eat and convert it into ATP, the form of energy our cells can actually use.
I think of ATP as cellular currency. You can eat carbohydrates, fats, and protein, but your cells still need to convert those nutrients into something they can spend.
Your heart needs ATP to beat. Your muscles need it to contract. Your liver needs it to perform countless metabolic reactions. Your brain requires an enormous amount of energy to think, communicate, regulate, and repair.
This is one reason I think cellular energy deserves more attention when we talk about fatigue.
The tissues with particularly high energy demands—including the brain, heart, skeletal muscle, kidneys, and liver—depend heavily on healthy mitochondrial function.
That doesn’t mean brain fog or muscle fatigue proves that your mitochondria are dysfunctional. It means energy production is one piece of a much larger clinical picture.
Your Mitochondria Respond to How You Live
One of the things I find most fascinating about mitochondria is that they aren’t static.
They respond to their environment.
Sleep, exercise, nutrition, metabolic health, inflammation, medications, smoking, alcohol, and certain environmental exposures can all influence mitochondrial biology directly or indirectly.
Exercise is a great example.
When we repeatedly ask our muscles to produce more energy, the body adapts. Aerobic exercise stimulates signaling involved in mitochondrial biogenesis—essentially improving our capacity to produce energy. This is one of the many reasons I care about cardiovascular fitness and why we measure things like VO₂ max at Nova.
Strength training matters too. Muscle is metabolically active tissue, and maintaining it becomes increasingly important as we age.
But more isn’t always better. Training without adequate recovery, chronically under-fueling, and consistently sacrificing sleep in order to fit in another workout are not necessarily helping your health.
I care much more about what you can do consistently.
Nutrition Matters
Mitochondria need raw materials to perform the biochemical reactions involved in producing energy.
B vitamins, magnesium, iron, amino acids, fatty acids, and other nutrients all participate directly or indirectly in cellular energy metabolism.
This is where the wellness world can take a reasonable concept and run too far with it.
If certain nutrients are required for mitochondrial function, it does not automatically follow that taking large amounts of those nutrients will give you more energy.
More is not always better.
If someone is iron deficient, correcting that matters. If someone has a meaningful nutritional deficiency or inadequate intake, we address it. But I would much rather identify what someone actually needs than hand everyone the same bag of “mitochondrial” supplements.
Food comes first.
A dietary pattern built around adequate protein, plants, fiber, healthy fats, and minimally processed foods supplies an enormous range of nutrients involved in cellular metabolism.
And metabolic health matters here too. Insulin resistance, chronically elevated glucose, and excess visceral fat are associated with oxidative stress and alterations in mitochondrial function.
Again, everything is connected.
Oxidative Stress Isn’t Quite What Social Media Makes It Sound Like
Another term that comes up constantly in discussions about mitochondria is oxidative stress.
As mitochondria produce energy, reactive oxygen species—or ROS—are generated. You’ll often hear these described simply as “bad” molecules that we need antioxidants to eliminate.
The biology is much more interesting than that.
We actually need some reactive oxygen species. They act as signaling molecules and are involved in normal physiological adaptation. Exercise itself temporarily increases oxidative stress, and some of that signaling helps drive the beneficial adaptations we get from exercise.
The issue is balance.
When the production of reactive molecules chronically exceeds our antioxidant and repair capacity, oxidative stress can contribute to cellular damage.
Smoking, excessive alcohol intake, metabolic dysfunction, chronic inflammation, poor nutrition, and certain environmental exposures can contribute to oxidative burden.
So my goal isn’t to help patients “eliminate free radicals.” That isn’t possible—or desirable.
I want to create an environment in which the body can maintain a healthier balance.
If You’re Exhausted, Start With the Right Question
This is the part I think matters most.
If you’re tired, I don’t want you leaving this article thinking you need a mitochondrial supplement.
I want you asking why.
Are you actually sleeping well—or simply spending eight hours in bed?
Are you getting enough iron, protein, and other essential nutrients?
How is your thyroid function? Are you in perimenopause or menopause? Are you insulin resistant? Could you have sleep apnea? Are you exercising enough to build cardiovascular capacity and muscle—or exercising so much that you never recover?
What medications are you taking? How much alcohol are you drinking? How much stress is your body carrying?
Sometimes there is one clear answer. Often, there are several smaller factors interacting with one another.
That’s one of the reasons I practice integrative medicine. I still want to identify or rule out conventional medical causes of fatigue. But I also want to understand the physiology around them: sleep, nutrition, hormones, metabolic health, movement, stress, inflammation, environmental exposures, and cellular energy.
We don’t need to blame every unexplained symptom on the mitochondria.
But understanding how our cells make energy gives us another lens through which to understand why someone may not feel as well as they should.
And importantly, many of the things that support healthy cellular energy aren’t exotic at all.
Sleep. Movement. Muscle. Cardiovascular fitness. Nutrient-dense food. Metabolic health. Recovery. Avoiding smoking. Being thoughtful about alcohol. Correcting actual deficiencies when they exist.
The fundamentals still matter.
If persistent fatigue is affecting how you feel, function, or live your life, we can take a more comprehensive look at what may be contributing. At Nova Wellness, our goal is to understand the whole picture and build a plan around you—not simply chase a symptom or a lab value. You can schedule a consultation with our team if you’d like to explore that approach.
This article is for educational purposes and is not a substitute for personalized medical advice.