Fatigue is a very general term and can be related to many chronic diseases.  

The body has such an innate ability to initiate processes to help protect the body. Every cell or organ of the body has a physiological resilience, which is the immediate ability to handle stressors, and then there is the long-term capacity of the body to handle stressors.  An example of an immediate response is how well the pancreas can handle an influx of food (glucose). The glucose level should fall back to a normal level in 2 hours.  Poor nutrition, genetics, toxins, and stress can all contribute to overburden on the pancreas and the inability of the body to control glucose long term.

Your body sends signals when there is imbalance, such as fatigue and mood changes, and it is important to recognize when these signals become chronic. All body systems are connected so it is important to consider how all the body systems are communicating in understanding issues with fatigue or mood changes.  Imbalances within the body that can affect fatigue and mood (chemical imbalances) are poor nutrition, hormone dysfunction, immune imbalances, poor digestion, imbalanced detoxification, poor energy production (mitochondria), and poor communication between the gut and the brain.

Your body simply is not able to function in an optimal manner without good nutrition.  Most people are deficient in the micronutrients needed to fuel our brains.  Nutritional deficiencies are due to processed food, poor soil, pesticides or herbicides, or the inability to absorb the nutrients we do consume. You are what you eat but also what you can absorb.  Nutritional deficiencies can influence some genetic variants, causing some mood changes.  In addition, the recommended daily allowance of vitamins and minerals may not be sufficient for most people who are immune compromised or have genetic variations.

Example:  There are several genetic variants that can affect how you turn folate from food into an active form the body can use.  A diet low in folate, can make it more difficult for the body to get the active form. Also, a diet high in processed food, which typically has folic acid, is more difficult to convert to an active form of folate and creates more a burden with an added folate variant.  Folate is important in supporting the neurotransmitters that handle stress and can affect your mood.

Hormones (from the reproductive organs, thyroid, pancreas, and adrenal glands) are the main communication signals of the body that communicate with your brain. Poor nutrition and excess fat mass can cause all hormones not to function as well.  In the example on the pancreas above, this can lead to fluctuations in mood when the glucose is not stable.  Hormone dysfunction affects our sleep, hunger, mood, and our metabolism. Vitamin D is typically thought to only affect your bones.  Vitamin D supports the immune system, reduces inflammation, and supports energy.  You might feel more sluggish with a low vitamin D.  Chronic stress can cause adrenal dysfunction, thus abnormal cortisol from stress during the day can affect how you sleep at night.  If stress is chronic, then depression, anxiety, insomnia become worse.

The immune system is a complex set of cells throughout the body but greater than 75% of immune related tissue is found in the gut. Your gut is confronted with different bacteria, viruses, and toxins daily. A diet high in sugar, low in fiber, acid blocking medications, antibiotics, and stress can cause significant inflammation in the gut wall.  The body does a good job of recognizing what is a foreign invader, but genetics can disrupt this process, and then toxins can exit the gut wall and invade the body.  Toxins invading the body can cause an array of mood changes and fatigue.  Many of the neurotransmitters (like serotonin) that affect mood have receptors in the gut and inflammation in the gut can affect the level of serotonin that makes us all calm.  The gut is considered the “second brain” as most signals to the brain come from neurotransmitters in the gut. 

Example: Neurogenerative changes in the brain can present with mood changes, memory loss, anxiety, and depression. Inflammation throughout the body, mostly in the gut wall, allows toxins to attack the brain. Genetics may be involved in the process also, if the genes that break down toxic neurotransmitters is affected.

Your body is confronted by toxins and pollution daily, in addition to the pollutions your body makes just to function. There are processes to rid the body of these toxins and when these processes are blocked, you can feel fatigued and experience mood changes.  Earlier, I mentioned how your body can handle immediate stressors but overtime, your body might reach a tipping point.

Example:   Your body is exposed to a certain degree of heavy metals (mercury, arsenic, lead), some in food from soil or water.  If you have some genetic variants that support the detoxification pathway and you are exposed to lead paint, or live near a coal plant, then this can build up in your system.  Environmental toxins, gut inflammation, and nutritional deficiencies, combined with some genetic variants, can be contributing factors in memory changes, anxiety, fatigue, and depression.

As mentioned, chronic fatigue and mood changes are signals that there is likely underlying dysfunction in the body.  The body may be trying to initiate processes to fight inflammation, infection, or the burden of poor nutrition.