5 Leading Causes of Fatigue

I am an avid listener of health podcasts. One of my favourites that I listen to while commuting from our home in North Gower to our clinic in downtown Ottawa is the Dr Michael Ruscio Radio show.  On his weekly show, he interviews different functional medicine experts. This week’s show featured my friend and local Functional medicine practitioner, Dr Carri Dryzka talking about the causes of fatigue.

Since I thought they did such a great job and so many of my clients complain of tiredness, I thought I would summarise what said in this blog.

5 Leading Causes of Fatigue

When looking for the root cause of fatigue or any other symptom, for that matter, it is best to start with the simplest explanation.

1. Vitamin-R Deficiency

There is not a vitamin R. Vitamin-R is a term coined by Dr Carri to mean Rest, Relaxation and Recreation. If you have a Vitamin-R deficiency, you are not getting enough rest, relaxation or recreational time in your life. Rest time means are you getting enough healthy sleep. Relaxation time means spending time doing restful activities or hobbies that allow your body to recuperate. Recreation time means doing exercise that is fun, gets you moving and allows you to stop thinking about life stresses. Dr Carri’s fun recreation is boxing. So if you are feeling weary, all the time check first that you are getting enough vitamin R.

2. Blood Sugar Imbalances

One of the most common but frequently overlooked causes of fatigue is blood sugar imbalances. You can experience fatigue both when your blood sugar is too low or too high. The medical term for low blood sugar is hypoglycemia. As well as fatigue a common symptom of hypoglycemia is “Hangry”, which means that you get irritable when you leave if too long before eating. A simple solution is to ensure that you don’t skip meals and eat small and frequently. When you have too much sugar in your blood, this can be a sign you are on the way to or have pre-diabetes or diabetes. An early symptom of high blood sugar is feeling tired after eating. A simple solution is to eat fewer carbohydrates, such as bread and pasta and more protein and healthy fats.

3. Food Sensitivities and more

In the words of Anne Wigmore, “The food you eat can be either the safest and most powerful form of medicine or the slowest form of poison.”  Regarding fatigue, there are some different ways food can negatively affect us:

Food sensitivities

Food sensitivities occur where undigested food proteins react with your immune system to create inflammation in the gut and elsewhere in the body. This inflammation can lead to fatigue. The two most common food proteins that humans react to are gluten and casein. If you suspect that your fatigue is caused by a food sensitivity, then the two most scientifically validated ways to identify the culprits are an elimination diet or an IgG Blood Food Allergy Test. In my practice, I also use applied kinesiology muscle testing which has helped me diagnose food sensitivities in thousands of clients.

Histamine Intolerance

Histamine is a chemical that your immune system produces when it encounters an allergen. Some people can develop an excess of this chemical in their body. Symptoms of excess histamine or histamine intolerance include fatigue, headaches, hives and heartburn. Histamine intolerance can because by:

  • Where your body does not break down histamine very well.
  • Bacterial overgrowth in the small intestine.
  • Parasites
  • If you eat foods high in histamine.

If you suspect that your fatigue is caused by histamine intolerance, you can try following a low histamine elimination diet.

Food Intolerances

A food intolerance occurs when your digestion is unable to break down a particular part of a food. The most traditional food intolerance is to lactose. Lactose is the sugar component found in dairy. For some people, as they get older their digestive system stops producing the enzyme lactase that assimilates lactose. If you have a lactose intolerance and consume dairy products, it may cause you to experience fatigue.

4. Gut infections, anaemia and inflammation

Gut infections may cause you to experience fatigue directly by stimulating inflammation in the body or indirectly by inducing nutritional deficiencies or anaemias. The two most common gut infections are small intestinal bacterial overgrowth (SIBO) or parasites. Both these infections can lead to iron and Vitamin B12 deficiency or anaemia, which both cause fatigue. You can test for SIBO using a breath test and for parasites using a stool test. Testing for iron and B12 can be done through you family physician although it is important to get a second opinion on your results from a Functional Medicine practitioner or Naturopathic Doctor.

5. Low Thyroid Function

Symptoms of low thyroid or hypothyroidism include fatigue, weight gain, hair loss, constipation, and depression. The most common form of hypothyroidism is Hashimoto’s disease which is caused by your bodies immune system attacking your thyroid i.e., autoimmunity. The most frequent trigger for Hashimoto’s is gluten. You can test for Hashimoto’s through a blood test looking for Thyroperoxidase and Thyroglobulin antibodies.


This article in not intended to provide medical advice, diagnosis or treatment.

Now I’d like to hear from you. Do you suffer from IBS? Have you been confused about what diet to try? Do you have any other suggestions that have worked well for you? Let us know in the comments below.


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