Fatigue Explained: What Is It and Why It Happens

Fatigue is one of the most common reasons people seek medical care—yet it’s often misunderstood, brushed off, or treated as something you just need to “push through.” In reality, fatigue is more than just being tired. It’s a signal from the body that something deeper is out of balance. Understanding why fatigue happens is the first step to finding lasting relief.  

Fatigue, What Is It Really?

Fatigue is not just low energy. It’s a persistent lack of physical, mental, or emotional stamina that doesn’t improve with sleep. It can affect concentration, motivation, mood, immune function, and quality of life. While everyone experiences temporary tiredness from time to time, chronic fatigue indicates an ongoing problem that deserves attention.

Unfortunately, many conventional approaches focus on treating fatigue with quick fixes—caffeine, stimulants, or antidepressants—rather than addressing the root causes. In our office we utilize naturopathic medicine principles and testing that aim to uncover what’s underneath.

What Causes Fatigue?

There are many possible contributors to fatigue, often overlapping and compounding over time. Here are some of the most common:

1. Iron Deficiency

Iron is critical for oxygen transport in the body. Without it, cells can’t generate the energy they need. Women, especially those with heavy menstrual cycles or during pregnancy, are particularly susceptible to low iron or ferritin levels. Even if your lab results are in the “normal” range, they may not be optimal.

2. Chronic Infections

Ongoing infections—like SARS-CoV-2 (Long COVID) or reactivated Epstein-Barr virus (Mono)—can leave a lingering impact on the immune system and energy production. These infections may not cause obvious symptoms, but they create an inflammatory burden that leads to deep, systemic fatigue.

3. Toxin Accumulation

We are exposed daily to environmental toxins—heavy metals, pesticides, mold, plastics—that can burden the liver, disrupt hormones, and impair mitochondrial function. When detox pathways are sluggish or overwhelmed, fatigue is often one of the first signs.

4. Nutrient Deficiencies and Malabsorption

Even if you eat a nutrient-rich diet, poor digestion or malabsorption can prevent your body from using what you take in. Low stomach acid, pancreatic insufficiency, or an unhealthy gut microbiome can all lead to deficiencies in key fatigue-fighting nutrients like B12, magnesium, iron, folate, and vitamin D.

5. Mitochondrial Dysfunction

Your mitochondria are the powerhouses of your cells—responsible for generating ATP, your body’s energy currency. Mitochondrial dysfunction, often triggered by infections, toxins, or nutrient deficiencies, can lead to widespread fatigue that feels like your energy system is simply offline.

6. Adrenal Fatigue and Chronic Stress

When stress is prolonged, your adrenal glands may not be able to keep up with the constant demand for cortisol and other stress hormones. This “burnout” can manifest as poor resilience, low morning energy, afternoon crashes, or feeling wired but tired.

7. Suboptimal Thyroid Function

Even if your TSH levels are within the standard lab range, your thyroid may not be functioning optimally. Low free T3, high reverse T3, or autoimmune thyroiditis (Hashimoto’s) can all contribute to fatigue, cold intolerance, brain fog, and weight changes.

8. Hormonal Imbalances

Low estrogen, progesterone, or testosterone can lead to fatigue, especially during perimenopause, menopause, or andropause. These hormones influence neurotransmitters, metabolism, sleep, and motivation.

9. Gut Microbiome Imbalance and Parasites

Your gut microbiome plays a central role in energy, immunity, and nutrient synthesis. A lack of microbial diversity, overgrowth of harmful bacteria, yeast (like Candida), or parasites can drain your system. Parasites are often overlooked as a cause of fatigue, yet they can create chronic inflammation, disrupt nutrient absorption, and provoke immune stress that leaves you feeling depleted.  To check for this we do a stool test.  The gut-brain-axis is closely related to the energy one has because these micro-organisms make the amino acid precursors to serotonin, dopamine and adrenaline. 

Why Are My Labs Normal?

One of the most frustrating things patients hear is: “Your labs are normal.” Yet they know something isn’t right. That’s because traditional lab work is often limited in scope and designed to catch disease—not imbalance.

Fatigue is often the result of functional problems—issues that don’t yet meet the threshold for disease but are still profoundly affecting your health. This is where deeper testing comes in.

In my practice, we often run:

• Organic Acids Testing – to assess mitochondrial function, nutrient status, neurotransmitter metabolism, and more
• Toxin Testing and Heavy Metal Testing – for hidden burdens like lead, mercury, glyphosate, or mold mycotoxins
• Comprehensive Stool Testing – to evaluate digestion, inflammation, gut bacteria, yeast, and parasites
• Advanced hormone panels – including adrenal, thyroid, and sex hormones

These deeper dives often uncover what routine bloodwork misses—and open the door to targeted, personalized treatment.

You Deserve Real Energy

Fatigue is not just in your head—and it’s not something you have to accept as your new normal. It’s your body’s way of asking for change. With the right information and a whole-person approach, you can uncover the real reasons behind your fatigue and reclaim your energy.