A perspective on fat intake in athletes

Performance in endurance events is dependent upon the maximal aerobic power , the percentage of that power that can be sustained and the availability o f substrates (carbohydrates [CHO] and fats). The purpose of this paper is t o present a perspective of recent studies that demonstrate the role of fat intake and oxidation on endurance performance. Studies have shown that fati gue is associated with reduced muscle glycogen and that increasing muscle g lycogen or blood glucose prolongs performance while increasing fat and decr easing CHO decreases performance. This has led to an emphasis on CHO intake in athletes in endurance sports, which quite often leads to low caloric in take. It is well known that trained subjects have higher levels of fat oxid ative capacity, which spares glycogen during endurance sports. Data from re cent studies in trained athletes, who were fed iso-caloric high-fat diets ( 42% to 55%) that maintained adequate CHO levels, have shown an increase in endurance in both men and women when compared to diets composed of low fat intake (10% to 15%). The magnitude of the effect on endurance was significa nt at high percentages of maximal aerobic power and increased as the percen tage of maximal aerobic power decreased. Based on this review, a baseline d iet comprising 20% protein, 30% CHO and 30% fat, with the remaining 20% of the calories distributed between CHO and fat based on the intensity and dur ation of the sport, is recommended for discussion and future research.