A steaming bowl of oatmeal sounds like the perfect stick-to-your-ribs breakfast, designed to give you energy and keep you feeling full all morning. But if eating a bowl of oatmeal has you feeling more like you need a nap, something in your breakfast bowl may not be good for you. It could be the oats, the additives or the sugar you add.
When you eat, more blood than normal rushes to your intestinal tract to aid in digestion. This diverts blood away from your brain and could cause a feeling of tiredness. Carbohydrates, especially refined carbohydrates such as sugar, also can cause fatigue after eating by raising your seratonin levels. Seratonin, a neurotransmitter, helps you fall asleep. Sugar raises your insulin levels, which releases tryptophan, which converts to seratonin.
If you suffer from reactive hypoglycemia, your body doesn't process carbohydrates well. Since oatmeal, a grain, contains carbohydrates, eating a bowl may raise your blood glucose levels quickly. Your body release large amounts of insulin to help cells absorb the glucose. Your blood sugar then falls rapidly, causing fatigue, shakiness, headache, difficulty thinking and tremors. If you add sugar to your oatmeal or eat processed oatmeal with sugar added, especially on an empty stomach, you have a higher risk of experiencing a hypoglycemic reaction. Adding protein to your meal and reducing the amount of sugar you add to oatmeal may decrease hypoglycemic reactions.
As many as one in 133 Americans suffer from gluten sensitivity, also known as gluten intolerance or celiac disease, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Oats do not contain the gluten protein that causes problems for people with celiac disease, but they're often processed in the same manufacturing plants that process wheat, which does contain gluten. Cross-contamination can occur during processing or in fields where oats grow, if wheat grows nearby. Celiac disease can cause fatigue in addition to gastrointestinal symptoms.
If you're eating commercially flavored oatmeal, you may have a reaction to additives such as food coloring, preservatives or other added chemicals. Processed flavored oatmeal may also contain a larger amount of sugar. Try substituting plain oats rather than packaged processed oatmeal to see whether this decreases your fatigue after eating oatmeal.