EFFECT OF A HIGH OR A LOW-FAT DIET ON CARDIOVASCULAR RISK-FACTORS IN MALE AND FEMALE RUNNERS

Dietary fat may be associated with coronary heart disease (CHD). Studi es suggest that restricting fat intake may compromise endurance perfor mance and that increasing fat intake may improve endurance performance . We studied the effects of varying dietary fat intake on CHD risk fac tors in runners. Twelve male and 13 female runners increased fat from 16% to 30% of daily calories (4 wk each). Of this group, six males and six females increased fat to 42% of daily calories (4 wk). Physiologi cal and lipoprotein risk factors were measured after each diet. Result s were analyzed by repeated measures ANOVA. Increasing dietary fat fro m 16% to 42% of daily calories did not change adiposity, weight, heart rate, blood pressure, serum triglycerides, total cholesterol, LDL cho lesterol, Apolipoprotein B, or the Apo Al/Apo B ratio. Compared with t hose eating higher fat, subjects eating 16% fat had lower HDL choleste rol (50 +/- 3 vs 62 +/- 3 mg . dl(-1), P < 0.0001) and Apolipoprotein Al (111 +/- 6 v. 134 +/- 6 mg/dl, P < 0.0005) and a higher TC/HDL-C ra tio (4.05 +/- 0.27 vs 3.42 +/- 0.24, P < 0.0005). Runners who increase d fat intake to 42% further raised HDL cholesterol (61 +/- 6 to 69 +/- 5 mg . dl(-1), P < 0.04) without adversely affecting other lipoprotei ns. In conclusion, a 42% fat diet maintained favorable CHD risk factor s in female and male runners whereas a 16% fat diet lowered Apo Al and HDL-C and raised the TC/HDL-C ratio.