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Once in the body both simple and complex carbohydrates are converted to glucose (blood sugar). Blood sugar is used to fuel our immediate needs for glucose. The body also stores glucose in the muscle cells as well as the liver as glycogen which can then be converted back to glucose for energy. As you probably know, the supply of muscle glycogen is limited.

When this supply begins to run out and/or when the blood glucose level drops, the liver, which also stores glycogen, releases glucose into the bloodstream where it can be carried to and used by the working muscles. This supply, like the muscle glycogen, is limited and can also become depleted after fast running or one to two hours of moderate running. A key adaptation to training is that your muscle cells begin to store more glycogen as a result of being depleted and replenished through training.

The second primary nutrient is fat. Like carbohydrates, fats provide energy (nine calories per gram). However, fats also serve a variety of other functions in the body. These functions include (1) offering protection for the other tissues (i.e. the major organs of the body), (2) allowing insulation from the cold, (3) storing the fat-soluble vitamins, and (4) comprising the major structural component of cell walls.

Fats can be classified as (1) saturated, (2) poly-unsaturated or (3) mono-unsaturated. The saturation of each type of fat is based on the number of hydrogen ions attached to the fat molecule. Saturated fats have the most hydrogen ions attached, the poly-unsaturated fats have less, and the mono-unsaturated fats have the least hydrogen ions.

Saturated fats are the least healthy of the three types of fats and are characterized by remaining solid at room temperature. Common examples include lard and butter. Even though this type of fat is the least healthy, it is still required by the body in small amounts and therefore should not be totally eliminated from the diet.

Poly-unsaturated fat is healthier than saturated fat and is characterized by being semi-solid at room temperature. Many of today’s margarines and butter alternatives are made with poly-unsaturated fats and thus require refrigeration.

Mono-unsaturated fat is the healthiest of the fats and remains liquid at room temperature. Examples of mono-unsaturated fats include most natural oils, such as olive oil.

Food items that contain mono-unsaturated fats but have been hydrogenated (meaning that hydrogen ions have been added) are less healthy than non-hydrogenated fats. One must be careful to read the ingredients of each food eaten to watch for mono-unsaturated fats that have been hydrogenated called partially hydrogenated oils.

Shortly, food labels in the US will also list these “transfats” in the food item which will help us avoid this potentially unhealthy type of “hydrogenated” fat.

Experts recommend that distance runners obtain 20 to 30 percent of their daily calories from fats. In addition, approximately one-third of one’s fat calories should come from each type of fat (saturated, poly-unsaturated and mono-unsaturated).

All excess fat in the diet will be stored as adipose (fat) tissue, which increases “dead” body weight and decreases performance. Examples of foods containing significant amounts of fats are lard, butter, meats, some dairy products and most varieties of oils.

Fats should be avoided prior to a race or hard workout. Fats are slow to empty from the stomach and may cause cramps, due to the decreased blood flow to the stomach which occurs during running.

The third primary nutrient is protein. Experts can’t agree but the ranges recommended are from 10 to 30 percent of their daily calories from protein for runners. The average American eats two to three times the protein requirement each day but finicky runners (and those who break down easy from hard training) may need to focus on their protein intake.

Proteins are composed of small substances called amino acids. They function as the major component of every structure in the body and also provide four calories of energy per gram, though you hope that you don’t regularly have to ‘burn’ protein for energy.

As a result of training and racing, our muscles and tendons experience small tears or micro-traumas which are repaired by the protein in our diet. This fact is why we even see a renewed focus on adding some protein to the traditionally carbohydrate-loaded recovery drinks. Some athletes even find that supplementing with protein powder aids their recovery. Excessive protein in the diet places great strain on the kidneys so there’s no need to eat like a body builder. Meats, beans and nuts are common examples of foods which contain significant amounts of protein.

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