Performing an endurance activity requires fats and carbohydrates. Both of these fuels are significant in the endurance exercise but are required in different ratios depending on the individual fitness level, duration, and intensity of the activity. For enduring athletes, carbohydrates and fats are important as they strive to maintain their intensity for several hours. The major cause of exhaustion is depletion of carbohydrates in the muscle, liver, and blood. However, fat oxidation delays the onset of carbohydrates depletion. The sole purpose of fats in the endurance process is to achieve a maximum glycogen store in the muscles (Williams, 2012). During an endurance exercise, the body burns glycogen to provide the body with sugar, which fuels the exercise. Burning glycogen requires no intermediate metabolic steps as opposed to burning fats. Before fats can be used by the muscle, there is an intermediary metabolic process, which reduces the immediate availability of the fats. This means that fat is very efficient as a fuel in endurance exercises.
However, there is the argument of fats increasing weight. An athlete is more concerned with oxygen cost than the energy available. With the availability of oxygen, more energy is produced from carbohydrates as compared to fats. Arguing at an oxygen point of view, depending on fats for energy during an endurance exercise is not helpful. The oxygen levels at an endurance exercise are limited; in which case, the amount of energy required is better acquired from burning carbohydrates as opposed to fats (Volek, Noakes & Phinney, 2015). In addition, consumption of high-fat diets adds weight to the body requiring more energy for an athlete. The fact that burning of fats requires a metabolic step shows that it might be inefficient in the production of energy.