How do nutrition and exercise scientists know that carbohydrates work best for supplying energy to an endurance athlete?

Answer 1

A study was done in which athletes ate either a high-carbohydrate, a high-fat, or a normal mixed diet and were tested for how long they could continue an activity at the initial intensity (endurance time). The athletes who ate the high-carbohydrate diets could sustain the activity almost 3 times longer than the athletes who ate a high-fat diet. This may seem odd since fat supplies 9 calories per gram. It turns out that the muscles require a steady supply of glucose to make ATP (energy). The stored glycogen is most easily broken down but is not all used up at the same time. The muscles also break down fatty acids in conjunction with glucose to provide energy to the muscle cells for a long time. People who ate more carbohydrates in their pre-event meal stored more glycogen that their muscles could use as fuel, along with fatty acids, for sustained aerobic activity.