Your body does not digest fiber into nutrients to fuel your body. Instead, fiber is necessary to remove solid wastes from your body. If high levels of waste and metabolic byproducts build up in your body, they may contribute to fatigue, a feeling of low energy without sleepiness. Eating a high-fiber diet can help remove sources of fatigue, but they will not directly give you an energy boost.
Before your body can absorb food, enzymes must break foods down into individual nutrients, such as amino acids, simple sugars and fatty acids. Your body lacks the enzymes necessary to break fiber into pieces your body can absorb. Thus, fiber passes through your intestines unabsorbed, bringing unabsorbed nutrients, waste and excess water with it. By analogy, fiber is like a trash bag that allows you to remove large amounts of waste from your body. Without it, pieces would be left behind.
Fatigue can have many causes. Medical conditions, such as high blood sugar or cholesterol, can contribute to fatigue. When you are fatigued, you feel like you have no energy, and you avoid stressful or challenging tasks. You may not necessarily feel tired or sleepy. If fatigue persists or creates a significant disruption to your daily life, see your doctor.
Some waste, such as excess blood sugar or cholesterol, is excreted with bile into the intestines. Without fiber, these wastes would be reabsorbed by your body. A high-fiber diet can be a significant aid to reducing high blood sugar and cholesterol once the underlying medical cause is treated. Fiber also makes your bowel movements more regular, decreasing the bulk of stool you carry in your body.
You probably aren’t eating enough fiber. According to MayoClinic.com, men should eat 38 grams of fiber daily; women should get 25. Elderly men and women, respectively, should eat 30 and 21 g daily. High-fiber foods include fruits, vegetables, nuts, seeds and whole grains. Although a fiber supplement -- such as psyllium husk -- may be used to boost your fiber intake, it should only make up a minority of your daily fiber consumption.