Why Am I Always Tired? A Functional Medicine Approach to Chronic Fatigue

‘I am just tired all the time.’ In the years I have spent in functional medicine practice, this might be the single most common thing I hear. And the response many of these patients got before finding their way to my office was equally predictable: ‘Your labs look normal. Maybe try getting more sleep. It is probably stress.’

That is not a diagnosis. That is a dismissal. Chronic fatigue is always a symptom of something — and it is almost always findable and fixable with the right evaluation.

The Most Common Root Causes of Chronic Fatigue

Fatigue has dozens of potential drivers. In my experience, the most common — and most commonly missed — include:

• Thyroid dysfunction — subclinical hypothyroidism and Hashimoto is thyroiditis are epidemic and frequently missed with standard TSH-only testing
• Iron deficiency or anemia — particularly ferritin below 50 ng/mL, even when technically ‘in range’
• Vitamin D deficiency — profoundly impacts energy, mood, immune function, and mitochondrial efficiency
• B12 deficiency — especially in those taking metformin, proton pump inhibitors, or following a plant-based diet
• Adrenal dysfunction / HPA axis dysregulation — disrupted cortisol rhythm leaves you unable to generate morning energy or recover from stress
• Blood sugar dysregulation — roller-coaster glucose crashes throughout the day produce energy swings and afternoon crashes
• Sleep apnea — surprisingly common, often undiagnosed, and a major cause of unrestorative sleep
• Mitochondrial dysfunction — the energy-producing machinery in your cells can be impaired by nutrient deficiencies, toxin exposure, and chronic inflammation
• Chronic low-grade infections — Epstein-Barr virus reactivation, Lyme disease, and other stealth infections

Why ‘Normal’ Labs Might Still Be Missing the Problem

A standard annual physical typically checks CBC, basic metabolic panel, and TSH. This panel will miss: subclinical thyroid dysfunction, early insulin resistance, nutrient deficiencies, adrenal pattern disruption, and most infectious drivers. ‘Normal’ on these labs means you do not have an obvious acute disease — it does not mean nothing is wrong.

What a Fatigue Workup Actually Looks Like

At Fundamental Wellness of Nebraska, a comprehensive fatigue evaluation includes: a full thyroid panel, iron studies including ferritin, vitamin D and B12 levels, fasting insulin and glucose, four-point cortisol assessment, comprehensive nutrient panel, and a thorough sleep history. For persistent cases, we may also look at mitochondrial markers and infectious triggers.

The Fastest Wins

For most patients, fatigue has 2-3 primary drivers that, when addressed together, produce dramatic improvement. The most common ‘fast wins’ I see: correcting iron/ferritin, optimizing vitamin D, stabilizing blood sugar, and improving sleep quality. Many patients feel meaningfully better within 4-8 weeks of targeted intervention.