When you tell yourself that exhaustion is just part of getting older, you aren’t accepting reality, you’re abandoning the investigation before it begins.
I was a teenager when I first noticed that my body and my mind were in constant conversation. Not in a philosophical way, in a practical, daily, unavoidable way. When I ate dairy, I felt sick. When I felt sick, I didn’t want to go to practice. When I missed practice, my mood dropped. When my mood dropped, I made worse choices about food and sleep. The spiral was obvious to me even then, and I hadn’t yet taken a single university course in chemistry or psychology.
I went on to study both, because I already knew the mind influences the body and the body influences the mind, and I wanted to understand the mechanism. I wanted to know why sugar gave me a headache and made me crave more sugar. I wanted to know why certain foods made me unwilling to show up. These weren’t mysteries to solve academically. They were questions with real consequences in my life, in my sport, in my relationships.
That early education, part formal, part lived, is why I cannot accept a particular story people tell themselves about fatigue: I’m just getting older. This is normal. This is what aging feels like.
That story is not a diagnosis. It is not acceptance. In the wrong moment, it is the beginning of a slow catastrophe.
Here is what happens next. The person who has decided their exhaustion is an unavoidable feature of aging reduces their activity. They sleep more but wake unrefreshed. They reach for convenient food because they don’t have the energy to cook. They cancel plans. They stop going to the gym, not because they chose to, but because the cost now exceeds the perceived return. Deconditioning sets in quietly. Weight accumulates. Social withdrawal follows. Depression, which is, among other things, a profoundly fatiguing condition, begins to take hold.
Now there are four problems where there was once one. And here is the detail that makes this genuinely dangerous: deconditioning causes fatigue. Excess adipose tissue, particularly visceral fat, drives systemic inflammation and insulin resistance, both of which cause fatigue. Depression causes fatigue. The spiral does not just run downward, it loops. Each consequence becomes a new generator of the original symptom. The person is now running a metabolic deficit on multiple fronts simultaneously, and the intervention that could have interrupted it at step one, refusing to accept the premise, never came.
Consider three cases that should permanently retire the “aging” explanation for fatigue.
A person with hypothyroidism — any age — has their dose optimized. Their energy improves, often dramatically, within weeks.
A perimenopausal woman begins estrogen therapy. The fatigue she had normalized as her new baseline begins to lift.
A patient with low B12 — again, any age — receives repletion. The fog clears.
In none of these cases did aging reverse. What reversed was a correctable deficit. Thyroid hormone is required for mitochondrial function. Estrogen modulates sleep architecture, neurotransmitter activity, and cellular energy metabolism. B12 is essential for myelin integrity and red blood cell production. When any of these fall below the threshold the body requires to run efficiently, the system slows. It has to. Energy output is a downstream consequence of upstream biochemistry and that biochemistry is measurable, addressable, and improvable at any age.
The age is not the variable. The deficit is.
I have been measuring resting metabolism for over a decade, the actual rate at which a patient’s body converts fuel to energy at rest, and the ratio of fat to carbohydrate it is burning to do so. When someone tells me they are exhausted, I do not start with the assumption that their age explains it. I start with data. What is their resting metabolic rate compared to what their body should produce? What substrate are they burning? Is their thyroid, adrenal, or sex hormone axis under strain? Are their cells getting what they need?
When we find the answer and correct it, through targeted nutrition, hormone optimization, nutrient repletion, structured movement, or all of the above, I watch the numbers change. The metabolic signature of fatigue is not a permanent feature. It shifts. That is not wishful thinking. I have the measurements to prove it.
Aging does create conditions that make fatigue more likely. Hormone levels shift. Nutrient absorption declines. Sleep architecture changes. Schedules that once accommodated recovery no longer do. Chronic stress accumulates. The window between stimulus and adequate rest narrows. These are real physiological changes, and pretending they do not happen serves no one.
But there is a difference between conditions that predispose and causes that are fixed. Aging predisposes. It does not sentence. A 68-year-old can build muscle. A 55-year-old can optimize her hormones. A 45-year-old depleted in magnesium, iron, or B12 can be repleted. The physiology that governs energy production responds to intervention at every decade of life. What it cannot respond to is the belief that nothing can be done.
That belief is where the real damage starts. When we internalize it, it removes agency. It extinguishes curiosity. It normalizes a trajectory that was, at that moment, still changeable.
The mind and body are not separate systems debating each other. They are one system, narrating itself. What we believe about our bodies shapes what we do with them and what we do with them changes the biology.
I learned that as a teenager reaching for a second sugary drink that I already knew would make me feel worse. The knowledge was not enough on its own. But it was the beginning. Once I understood the mechanism, I could intervene in it. I could make a different choice not because I had more willpower, but because I had more information and the information changed the meaning of the choice.
Do not accept fatigue as a verdict. Accept it as a signal, one worth investigating with the same seriousness you would give to any symptom that limits your life.
The investigation does not have to be complex. A hormone panel. A nutrient screen. A grip strength assessment, which tells us more about biological age and metabolic resilience than most people realize. Find something to measure. Something to work on. Make a plan around it and track what changes.
Objective data is not the enemy of hope, it is the foundation of it. When you can see where the deficit lives, you can address it. When you address it, the system responds. Energy is not a luxury of youth. It is a product of physiology, and physiology, in every decade of life, is something we can work with.
Dr. David Duizer ND
PS. Our naturopathic doctors are trained to investigate fatigue at the root through objective testing, metabolic assessment, and individualized treatment plans that address the underlying deficit rather than the surface symptom. Whether your starting point is a hormone panel, a resting metabolism test, or a conversation about where your energy went, we can help you find it.
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