Research Library
The Effects of Varying Dietary Fat on Performance and Metabolism in Trained Male and Female Runners
Horvath, P.J., Eagen, C.K., Fisher, N.M., et al., "The Effects of Varying Dietary Fat on Performance and Metabolism in Trained Male and Female Runners," Journal of the American College of Nutrition, 19(1), 2000, pages 52-60.
The following information is available at Pub Med and was not written by Atkins professionals.
The purpose of this study was to examine the effects of low-, medium- and high-fat diets on performance and metabolism in trained runners. Twelve men and 13 women, all of whom ran an average of 42 miles a week, ate a low-fat diet consisting of 16% fat for four weeks. All then switched to a medium-fat diet (31% fat) for another four weeks. A subset of six men and six women followed a high-fat diet consisting of 44% calories from fat for another four weeks. At the end of each diet, participants were tested for endurance and maximal oxygen consumption (the greatest amount of oxygen breathed per minute). Blood levels of lactate, pyruvate, glucose, glycerol, triglycerides and free fatty acids were measured before and after these tests. Runners on the low-fat diet ate 19% fewer calories than did those on the medium- or high-fat diets despite the study’s design to have all groups eat the same number of calories. Body weight, percent of body fat, maximal oxygen consumption and anaerobic power were not affected by dietary fat intake. Runners who increased dietary fat intake from 16% to 31% increased endurance time by 14%. No differences were seen in blood lactate, glucose, glycerol, triglycerides and fatty acids when comparing runners on the low- versus the medium-fat diet. Those who increased dietary fat to 44% had higher blood pyruvate and lower lactate levels after the endurance run. Researchers concluded that a high-fat diet that provides sufficient total calories does not compromise anaerobic power.
The following information was written by Atkins professionals
Findings from this research can be applied to the Atkins Principle of Good Health. Controlled carbohydrate nutrition may improve athletic performance. Many athletes hesitate to consume a low-carbohydrate/high-fat diet for fear of detrimental effects on performance. They may be concerned with gaining weight and/or body fat or fear that burning fat rather than carbohydrate, would impair performance. This study refutes these ideas. Trained endurance runners eating more fat did not gain weight or body fat. Their oxygen consumption and anaerobic power were also not hampered in any way. Runners who ate more fat in this study actually increased endurance time.
