The muscles require an ample supply of blood during training, since a lot of the "pump" you experience is from blood swelling up your muscles. But if the digestive system is also using excess amounts of blood to digest a big meal, there won't be enough to go around and your muscles will suffer for it. When you eat too heavily before training, you are setting up a conflict in the body, a demand for excess in the blood in too many places at once. This is why parents are right when they tell children not to go swimming right after a big meal; lack of adequate blood supply to the muscles used in swimming can lead to problems like severe cramps.

Training with a full stomach can be a very unpleasant experience. You feel bloated, sluggish, and slow, and a really hard set can make you feel nauseated.

The body metabolizes food at different rates. It takes from two to six hours for the stomach to empty its contents. Foods rich in carbohydrates digest first, followed by proteins foods; fatty foods are the last to leave.

When you wake up in the morning and haven't eaten anything for eight to twelve hours, your body is depleted of carbohydrate. Since carbohydrate is needed to produce the glycogen the muscles need for intense contraction, it makes sense to eat a high-carbohydrate for breakfast before going to the gym to train in the morning.

A light meal of fruit, fruit juice, or toast can be eaten before you train and will give you energy without slowing you down. However, a breakfast that includes eggs, meat or cheese-all high in both protein and fats-will take longer to digest, so you would do better not to eat things like this before you train.

It is not a good idea to eat a big meal immediately after a workout either. You put your body under great stress when you train and you need to give your system time to return to normal, for the blood to leave the muscles and the stress reaction to diminish. This way your digestive system will function as it was designed to, turning your food into energy and masses of new muscle tissue. Wait awhile, then eat a well-balanced meal.