ABSTRACT
Dietary fat is a dense fuel source that is essential for normal cellular physiology and daily activity (Table 4.1). Internal fat depots throughout the human body comprise more than 50 times the amount of stored energy compared to stored carbohydrate, and for this reason alone fat becomes a critical fuel source for many types of athletic activities, particularly those of prolonged duration. In fact, typical body fat stores could allow a runner to run at least 800 miles (or more than 130 hours if running at a pace of six miles per hour) before depletion of fat depots will occur-although this concept is only accepted in theory when considering the rate-limiting steps of fat metabolism to be discussed further in this chapter. Fat has somewhat of a paradoxical role for competing athletes. On one end, its role in providing invaluable constituents to allow for hormone production, nutrient transport, and so on necessitates its intake, while its relatively high energy density often leads to concern over excessive energy intake, which can lead to undesired changes in body mass and body composition. In specic regard to nutrient timing, fat ingestion is a carefully approached topic as studies that have explored some aspect of fat loading or supplementation consistently report unfavorable gastrointestinal responses. Dietary fat intake throughout the day is essential, but from the standpoint of trying to promote ideal adaptations by manipulating food choices, fat intake can inhibit these adaptations under certain conditions. This chapter rst discusses lipids from a basic nutrition perspective and then outlines their role in metabolism during various exercise scenarios.
