Glucose, or blood sugar, is a vital source of energy for your body. Lack of this sugar causes symptoms ranging from mild fatigue to coma and even death. Although your body requires a regular supply of glucose from carbohydrate-rich foods, some types of carbohydrate foods can cause changes in blood sugar that lead to tiredness. Eating regular, balanced meals helps you avoid blood sugar swings that cause fatigue. Ask your doctor to check your blood sugar if you are regularly fatigued.
Glucose as Energy
A moderate and consistent supply of glucose gives you energy rather than making you tired. Carbohydrate-rich foods are your body's main source of glucose. Sources of carbohydrates include grain products, beans, vegetables, fruits and dairy products. When necessary, your body can convert fat and protein into glucose, but this process is less efficient. The hormone insulin allows your cells to take in glucose and use it as energy. In this way, insulin helps regulate the level of glucose in your bloodstream.
Hypoglycemia
Hypoglycemia occurs when your blood glucose levels fall below the normal range, meaning below 70 mg/dL. Because your body needs glucose for energy, too little glucose in your bloodstream may leave you feeling tired, weak or sleepy. Other symptoms include trembling, sweating and lightheadedness. Missing meals, eating too little and exercising strenuously can all lead to this condition. An excess of diabetes medication such as injected insulin can also cause hypoglycemia. To treat hypogylcemia, you should eat or drink something that provides at least 15 grams of quickly absorbed carbohydrates, such as five or six pieces of hard candy, and follow this with a balanced meal or snack within an hour.
Reactive Hypoglycemia
A type of hypoglycemia known as reactive hypoglycemia occurs when blood sugar falls too low after you eat, usually one to three hours after a meal, according to Dr. Maria Collazo-Clavell with the Mayo Clinic. Eating foods that rapidly raise blood sugar, such as foods high in simple sugars, is one cause of reactive hypoglycemia. The quick increase in blood sugar causes your pancreas to produce a large amount of insulin; this causes a rapid fall in blood sugar, resulting in hypoglycemia and related tiredness.
Stabilizing Your Blood Glucose Levels
To reduce your risk of reactive hypoglycemia, limit food and drinks high in simple sugars such as candy, cake and fruit juice, and avoid eating or drinking them on an empty stomach. Eating a nutritionally balanced meal or snack every two or three hours also reduces your risk of low blood glucose. Fiber-rich carbohydrate sources such as whole grains, beans and fresh vegetables help keep your blood sugar stable. Eating a protein or fat source along with carbohydrate-rich foods also stabilizes your blood sugar.
References
- National Digestive Diseases Information Clearinghouse; Your Digestive System and How It Works; April 2008
- National Diabetes Information Clearinghouse; Hypoglycemia; October 2008
- University of Illinois McKinley Health Center: Nutrition for Reactive Hypoglycemia
- University of California Los Angeles: Student Nutrition and Body Awareness Campaign; Glycemic Index; April 2001
- Mayo Clinic; Reactive Hypoglycemia: What Can I do?; Maria Collazo-Clavell; October 2010
