Fats are usually reduced in the diet

Fats

Fats are usually reduced in the diet of athletes in training. One reason for reducing the proportion of fat in the training diet is that fat is not directly used as a fuel for supporting muscular exercise. Even after fasting, the stimulated gastrocnemii of rats show no appreciable change in fat content whereas carbohydrate stores are much reduced. It is not until men undergo severe and protracted work leading to hypoglycemia that there is an increased utilization of fat. Subjects maintained on a fat-rich diet showed a smaller net muscular efficiency than when they were on a carbohydrate-rich diet.

By plotting R.Q. against net efficiency, extrapolation to pure fat metabolism (R.Q. of 0.70) indicated 11 per cent greater energy expenditure per unit of work than for pure carbohydrate metabolism (R.Q. of 1.0).

Even though fat-rich diets are associated with reduced endurance and muscular efficiency, the exclusion of all fat from the diet is not recommended. Aside from the important vitamins and minerals and certain essential fatty acids in fats, there appears to be a fatcontained factor that is necessary for the normal metabolism of carbohydrate. A disturbed carbohydrate metabolism has been observed in rats maintained more than a year on a fat-deficient diet. In the light of the above considerations it would seem that the amount of fat in the diet which will maintain a good nutritional condition and yet not materially reduce endurance or muscular efficiency is about 100 grams daily. Normal intake of fat should not supply more than 45 per cent of the total calories. The fat content of the diet during training for an athletic event in which particularly high levels of performance are desired may be reduced to 75 grams or 25 per cent of the total calories per day. The proteins and carbohydrates in this training diet would be approximately 15 per cent and 60 per cent, respectively, of the total calories per day.