Root Causes of Chronic Fatigue a Functional Medicine Doctor Looks For

Why Am I So Tired All the Time? Root Causes a Functional Medicine Doctor Looks For

"I'm sleeping eight hours, but I still wake up exhausted."

"By 2 p.m., I feel like I could fall asleep at my desk."

"My doctor says my lab work is normal, but I still don't feel like myself."

If any of these sound familiar, you're not alone.

Fatigue is one of the most common reasons patients seek care at Dr. Lisa Gengo's practice in Stamford, Connecticut. While it's normal to feel tired after a stressful week or a poor night's sleep, persistent fatigue is not something you should simply accept as part of aging.

Your body is designed to produce energy. When it doesn't, it's often trying to tell you something. The key isn't masking the fatigue—it's discovering what's causing it.

Fatigue Is a Symptom, Not a Diagnosis

Many people assume fatigue is simply part of getting older, raising a family, working long hours, or going through menopause.

While these life changes can certainly contribute, fatigue itself isn't a diagnosis.

Think of it like the check engine light in your car. The light isn't the problem. It's a signal that something beneath the surface needs attention.

Rather than simply reaching for another cup of coffee or an energy drink, it's important to ask a different question: Why is my body struggling to make energy?

At Dr. Gengo's practice, the goal isn't simply to cover up symptoms—it's to understand why they're happening in the first place.

What Causes Chronic Fatigue?

There usually isn't one single cause.

For many patients, fatigue develops because several systems in the body are no longer working together as efficiently as they once did.

Let's look at some of the most common contributors:

1. Thyroid Dysfunction

Your thyroid acts as your body's metabolic thermostat. Even subtle thyroid dysfunction can affect how every cell in your body produces energy.

Common symptoms include:

Fatigue
Weight gain
Brain fog
Constipation
Feeling cold
Dry skin
Hair thinning
Depression

Many conventional evaluations measure only TSH, but thyroid health is often more complex.

Depending on your symptoms and medical history, Dr. Gengo may recommend a more comprehensive thyroid evaluation that includes Free T3, Free T4, thyroid antibodies, and other laboratory markers to better understand how your thyroid is functioning.

Hashimoto's thyroiditis—the most common autoimmune thyroid condition—is especially common in women and can contribute to persistent fatigue long before obvious thyroid abnormalities develop.

Key Takeaway

Persistent fatigue should never be ignored simply because a single thyroid test falls within the normal range. A comprehensive evaluation may provide additional insight when symptoms continue.

2. Blood Sugar Imbalances

You don't have to have diabetes to experience blood sugar problems. In fact, insulin resistance often develops years before diabetes is diagnosed.

Signs may include:

Afternoon energy crashes
Brain fog
Sugar cravings
Weight gain
Increased belly fat
Feeling tired after meals

When blood sugar rises and falls throughout the day, your body is constantly trying to restore balance, which can leave you feeling physically and mentally exhausted. Rather than looking only at glucose, Dr. Gengo may evaluate additional metabolic markers to better understand how your body is regulating blood sugar.

3. Nutrient Deficiencies

Your cells require vitamins and minerals to produce energy. Even mild deficiencies can make a noticeable difference in how you feel.

Common deficiencies associated with fatigue include:

Iron
Vitamin B12
Vitamin D
Magnesium
Folate

Women are particularly susceptible due to menstruation, pregnancy, digestive disorders, dietary restrictions, and the hormonal changes that occur with aging.

4. Poor Gut Health

Your digestive system does much more than digest food. It's responsible for absorbing the nutrients your body needs to create energy.

When gut health is compromised, you may experience:

Bloating
Constipation
Diarrhea
Food sensitivities
Nutrient deficiencies
Chronic inflammation

Because the gut and immune system are closely connected, digestive issues can affect far more than your stomach.

5. Chronic Inflammation

Inflammation is a normal part of healing. However, when inflammation becomes chronic, it may contribute to ongoing fatigue and reduced quality of life.

Inflammation may be influenced by:

Autoimmune conditions
Poor metabolic health
Chronic infections
Lifestyle factors
Poor sleep
Stress

Identifying the source of inflammation is often an important step toward restoring energy.

6. Poor Sleep Quality

Sleeping eight hours doesn't always mean you're getting restorative sleep.

Conditions such as:

Sleep apnea
Snoring
Restless sleep
Frequent nighttime awakenings
Menopause-related hot flashes

Menopause-related hot flashes can prevent your body from reaching the deep stages of sleep needed for recovery. Many patients don't realize that poor sleep quality—not simply sleep quantity—is contributing to their fatigue.

7. Chronic Stress

Stress affects nearly every organ system.

Over time, chronic stress can influence:

Hormones
Blood sugar
Digestion
Immune function
Sleep
Mood

The result is often a body that feels constantly depleted. Managing stress isn't simply about relaxation—it's an important part of supporting long-term metabolic and cardiovascular health.

8. Hormonal Changes

Many women notice dramatic changes in their energy during perimenopause and menopause.

As estrogen and progesterone fluctuate, you may experience:

Brain fog
Poor sleep
Mood changes
Hot flashes
Weight gain
Fatigue

Hormones don't work independently. They influence thyroid function, metabolism, cardiovascular health, and blood sugar regulation, making a comprehensive evaluation especially important during this stage of life.

9. Could Your Heart Be Contributing?

Many people don't associate fatigue with heart health. However, women often experience cardiovascular disease differently than men.

Instead of chest pain, early symptoms may include:

Fatigue
Shortness of breath
Reduced exercise tolerance
General lack of energy

Because Dr. Gengo spent years as a Physician Assistant in cardiac surgery before becoming a naturopathic physician, she understands the importance of looking at fatigue through both a conventional and functional medicine lens. Protecting your energy also means protecting your heart.

What Does the Latest Research Say?

Current research suggests that chronic fatigue is often multifactorial, meaning several factors contribute simultaneously rather than a single diagnosis.

Studies have linked persistent fatigue with thyroid dysfunction, insulin resistance, sleep disorders, chronic inflammation, nutrient deficiencies, hormonal changes, and alterations in the gut microbiome.

Rather than evaluating each system independently, emerging research supports a more comprehensive approach that considers how these systems influence one another.

This systems-based perspective is a core principle of functional medicine and helps guide individualized care.

How Dr. Gengo Evaluates Fatigue

One of the most common frustrations patients share is hearing:

"Your labs look normal."

Routine laboratory testing can rule out many serious illnesses, but it doesn't always explain why someone continues to feel exhausted.

Depending on your symptoms and medical history, your evaluation may include:

Comprehensive thyroid testing
Iron studies and nutrient assessment
Blood sugar and insulin markers
Inflammatory markers
Hormone evaluation
Gut health assessment
Cardiovascular risk markers
Lifestyle, nutrition, and sleep review

Every patient is different, which is why testing should be personalized—not one-size-fits-all.

What Actually Helps?

Treatment depends on identifying the underlying contributors.

Your personalized plan may include:

Nutrition designed to support stable blood sugar
Strength training to preserve muscle and metabolism
Restoring healthy sleep habits
Correcting nutrient deficiencies
Optimizing thyroid health
Supporting gut health
Stress management strategies
Addressing cardiovascular risk factors when appropriate

The goal isn't another temporary solution. It's helping your body function the way it was designed to.

Frequently Asked Questions

Can my blood work be normal and I still feel exhausted?

Yes. Routine lab work may not identify every cause of fatigue. Nutrient deficiencies, thyroid disorders, blood sugar imbalance, sleep disorders, and other conditions sometimes require a more comprehensive evaluation.

Can Hashimoto's make me tired even if I'm taking thyroid medication?

Yes. Some people continue to experience fatigue despite treatment. Additional evaluation may help determine whether thyroid function is optimized or whether another condition is contributing to symptoms.

Can menopause cause fatigue?

Yes. Hormonal fluctuations during perimenopause and menopause commonly affect sleep, mood, metabolism, and energy levels.

Can poor gut health make me feel tired?

It can. Digestive issues may affect nutrient absorption and contribute to inflammation, both of which can influence energy production.

When should I see a healthcare provider?

If fatigue lasts more than several weeks, interferes with daily activities, or is accompanied by symptoms such as chest pain, shortness of breath, fainting, unexplained weight loss, or persistent fever, you should seek prompt medical evaluation.

Why Choose Dr. Lisa Gengo?

Dr. Lisa Gengo combines decades of experience in conventional medicine, cardiac surgery, naturopathic medicine, and functional medicine to help patients uncover the factors contributing to fatigue.

Rather than focusing on a single symptom, she evaluates how your thyroid, hormones, metabolism, cardiovascular health, gut health, nutrition, sleep, and lifestyle work together to influence your overall well-being.

If you're tired of feeling tired, you don't have to settle for "everything looks normal."

Ready to Get Your Energy Back?

If you're experiencing persistent fatigue and live in Stamford, Greenwich, Darien, New Canaan, Norwalk, Westport, or anywhere in Fairfield County, Dr. Lisa Gengo can help you take a deeper look at what may be contributing to your symptoms. Schedule your complimentary 15-minute Discovery Call to learn how a personalized, root-cause approach can help you restore your energy and improve your long-term health. Ready to get started? Give us a call to schedule your appointment! (203) 434-9143.

Medical Disclaimer

This article is intended for educational purposes only and should not be considered medical advice. Always consult your healthcare provider regarding your individual health concerns, diagnosis, and treatment options.

Dr. Lisa Gengo, a "health detective," excels in unraveling the underlying triggers of heart health challenges such as hypertension (cardiovascular health), gut disorders, thyroid disorders, and weight resistance. Her expert nutritional guidance is instrumental in addressing these concerns, which often play critical roles in conditions like weight gain, sleep disorders, and a spectrum of intricate medical issues. Click here to learn more about Dr. Gengo's holistic approach and specialized expertise. —Dr. Lisa Gengo's Functional Medicine Practice.