Functional Medicine: A Root-Cause Approach to Chronic Fatigue

Author: Rohan Smith | Functional Medicine Practitioner | Adelaide, SA

Quick Answer

If you feel persistently exhausted despite adequate sleep and “normal” blood tests, a functional medicine approach to chronic fatigue offers a framework for investigating why. Chronic fatigue is rarely caused by a single issue. Instead, it may be associated with subtle disruptions across multiple systems, including thyroid regulation, gut function, stress physiology, nutrient status, and post-viral immune responses. Functional medicine focuses on identifying these patterns rather than treating fatigue as an isolated symptom.

The Core Concept: Why Fatigue Persists When Tests Look Normal

Fatigue is not a diagnosis; it is a signal. In conventional care, testing is often designed to identify overt disease. Functional medicine examines how systems interact and whether they are operating optimally, even when results fall within reference ranges.

Chronic fatigue may be associated with impaired energy production, immune activation, hormonal signalling changes, or nervous system dysregulation. These processes can exist long before laboratory markers become clearly abnormal.

Common Root Causes Explored in Functional Medicine

Thyroid Regulation Beyond TSH

Thyroid hormones play a central role in cellular energy production. While thyroid stimulating hormone (TSH) is commonly used as a screening marker, it does not fully reflect thyroid hormone conversion, transport, or cellular responsiveness. Thyroid dysfunction beyond standard TSH testing may contribute to fatigue even when TSH appears normal.

Gut Health and Microbiome Imbalance

The gut influences nutrient absorption, immune regulation, inflammation, and neurotransmitter balance. Conditions such as dysbiosis or small intestinal bacterial overgrowth (SIBO) may be associated with fatigue through impaired digestion, inflammatory signalling, and altered metabolic by-products. These patterns are commonly explored when assessing gut microbiome imbalances and fatigue.

Stress Physiology and Nervous System Load

Chronic psychological or physiological stress can alter hypothalamic–pituitary–adrenal (HPA) axis signalling and autonomic nervous system balance. Over time, this may disrupt sleep quality, blood sugar regulation, immune resilience, and perceived energy levels. A deeper understanding of stress, nervous system health, and fatigue is often central to recovery.

Post-Viral and Immune-Mediated Fatigue

Following viral infections, some individuals experience prolonged fatigue that may be associated with immune activation, mitochondrial stress, or autonomic dysfunction. These post-viral fatigue patterns have gained increasing clinical attention in recent years.

How Functional Medicine Testing Differs

Functional medicine uses targeted testing to explore physiological patterns rather than isolated disease states. Depending on the individual, this may include expanded thyroid markers, gut microbiome analysis, nutrient assessments, hormone profiles, or metabolic testing. Results are always interpreted within clinical context rather than in isolation.

When to Consider a Functional Medicine Approach

• You experience persistent fatigue despite adequate sleep
• Standard blood tests are reported as normal
• Your fatigue worsened after illness, stress, or hormonal changes
• You have coexisting symptoms such as brain fog, digestive issues, or poor stress tolerance

Next Steps in Care

A functional medicine approach focuses on understanding your individual physiology. Interventions may include personalised nutrition, targeted supplementation, stress regulation strategies, sleep optimisation, and gut or hormone support. Plans are adjusted over time based on clinical response and objective data.

Key Insights

• Chronic fatigue is often multi-factorial rather than a single diagnosis
• “Normal” tests do not always reflect optimal function
• Functional medicine focuses on patterns, systems, and root causes
• Individualised care is central to long-term improvement

Working With Elemental Health and Nutrition

At Elemental Health and Nutrition in Adelaide, care is focused on uncovering why symptoms persist rather than simply managing them. If you are struggling with ongoing fatigue and feel you have exhausted conventional options, a functional medicine assessment may help clarify the next steps.

If you would like to explore whether this approach is appropriate for you, you can learn more about available services or book an initial consultation.

References

1. Institute of Medicine. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. National Academies Press; 2015.
2. Morris G, Maes M. Mitochondrial dysfunctions in chronic fatigue syndrome. Neuro Endocrinol Lett. 2014.
3. Jason LA, et al. Energy metabolism and fatigue. Fatigue. 2019.
4. Wirth K, Scheibenbogen C. A unifying hypothesis of ME/CFS pathophysiology. Front Immunol. 2020.
5. Chaker L, et al. Hypothyroidism. Lancet. 2017.
6. Taylor PN, et al. Thyroid hormone replacement therapy. BMJ. 2018.
7. Biesiekierski JR. What is gluten? J Gastroenterol Hepatol. 2017.
8. Quigley EMM. Gut microbiota and fatigue. Curr Opin Gastroenterol. 2019.
9. Pimentel M, et al. SIBO and systemic symptoms. Am J Gastroenterol. 2020.
10. Rao SSC, et al. Gut–brain axis. Gastroenterology. 2021.
11. McEwen BS. Stress and allostatic load. Ann N Y Acad Sci. 2017.
12. Charmandari E, et al. Stress response systems. Endocr Rev. 2018.
13. Hornsby WE, et al. Sleep, stress, and fatigue. Sleep Med Clin. 2020.
14. Proal AD, VanElzakker MB. Long COVID and post-viral syndromes. Front Microbiol. 2021.
15. Natelson BH, et al. Immune dysfunction in chronic fatigue. Clin Ther. 2021.
16. Jones JF, et al. Chronic fatigue mechanisms. Clin Infect Dis. 2019.
17. Rasa S, et al. Chronic immune activation and fatigue. J Transl Med. 2018.
18. Galland L. Functional medicine and systems biology. Altern Ther Health Med. 2014.