“Invisible illnesses” and conditions of chronic pain tend to be characterized by other symptoms too, such as intense fatigue and brain fog. Pain, fatigue and cognitive difficulties can have their roots in inflammation, and diet can be a driver of this, as explained in the basic diet information article. Other drivers of these symptoms include blood sugar dysregulation, gluten and food intolerances and nutrient deficits.
The brain is very sensitive to changes in blood sugar (glucose). Research has shown low glucose can alter the perception of pain . Low glucose can also contribute to fatigue . Dietary strategies that reduce wide blood sugar fluctuations can improve symptoms of pain and fatigue in chronic pain conditions.
What About Gluten?
Gluten is a protein found in grains such as barley, rye, wheat and oats. Gluten sensitivity can result in a wide variety of symptoms, including pain, fatigue and brain fog.
Sensitivity to gluten can range from mild to extreme, with the extreme form being known as celiac disease or sprue. Blood tests and biopsies are usually performed to confirm a celiac disease diagnosis, and blood tests are also available to test for milder forms of sensitivity, such as non-celiac gluten sensitivity (NCGS).
If you are gluten-sensitive, eliminating gluten from your diet may result in symptomatic improvement. If you are not gluten-sensitive, eliminating gluten is unlikely to produce any symptomatic improvement aside from placebo effect.
Food intolerances to substances other than gluten can also contribute to the development of pain, fatigue and brain fog. Talk to your healthcare provider about the risks and benefits of an elimination diet for identifying food sensitivities.
Other Nutritional Considerations
Pain, fatigue and financial limitations may underlie decisions that result in a sub-optimal diet and nutrient inadequacies. Food intolerances and digestive system conditions such as Irritable Bowel Syndrome may also contribute to the development of nutrient deficiencies. Fibromyalgia and CFS, for example, seem to create nutrient deficiencies and/or higher than normal requirements for certain nutrients. If you are concerned you may be low in a specific nutrient, please contact your healthcare practitioner for assessment prior to experimenting with supplements because some can induce toxicity symptoms and/or interact with medications.
Managing Blood Sugar
People who live with chronic pain can be limited in their capacities for activity, including exercise. When dietary intakes are not balanced with physical activity, metabolic changes leading to obesity and type 2 diabetes can occur.
Blood sugar management involves moderating your total caloric intake according to your level of physical activity, as well as the frequency of meals and their content. Dietary approaches, such as the Dysglycemia Diet, that focus on whole foods, lots of fiber, and food sources of probiotics promote better blood sugar stability.
How To Make Dietary Changes
With the exception of food avoidance due to intolerance or allergy, most people get better results when they make incremental dietary change over time than when they implement drastic change suddenly. Human bodies like consistency and have many regulatory processes (homeostatic mechanisms) that promote it. Abrupt change interferes with this preferred state.
When you implement The Dysglycemia Diet, you may begin to eat more pulses (beans and lentils) and other sources of fiber than you are used to. Increasing your fiber intake or introducing foods you don’t consume regularly can result in digestive upset.
The key to avoiding this is to start low and go slow. Start with small amounts, eaten once per day. As you adapt to the change, try increasing the amount or frequency but not both at the same time.
Remember the basics too: choose whole (unprocessed) foods, avoid CRAP, spread your calories through the day, and maintain your hydration level.
 Gibbons, Christopher H., et al. “Experimental hypoglycemia is a human model of stress-induced hyperalgesia.” PAIN® 153.11 (2012): 2204-2209. http://pfizerpro.com.co/sites/g/files/g10012911/f/publicaciones/2012_153_11_Experimental-hypoglycemia-is-a-human-model-of-stress-induced-hyperalgesia_2204_2209.pdf
 Cryer, Philip E. “Symptoms of hypoglycemia, thresholds for their occurrence, and hypoglycemia unawareness.” Endocrinology and metabolism clinics of North America 28.3 (1999): 495-500. http://www.ncbi.nlm.nih.gov/pubmed/10500927