Heimdal, J. E., Karwacki-Marugg, C., & Heimdal, J. N. (1998). Effect of 24-hour high fat diet on active subjects' maximal aerobic capacity. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 213.

Active Ss (N = 12) were tested under normal diet (15% fat) and high fat diet (56% fat) conditions. The high-fat diet was ingested the night before and in the morning of the testing. Maximal aerobic capacity, ratings of perceived exertion, and resting exchange ratio were measured after a standard testing protocol under each dietary regimen.

There were no differences between ratings of perceived exertion or resting exchange ratio. However, VO2max decreased by 6% after the fat diet.

Individuals may perceive their work to be the same after both forms of diet but that does not reflect the diminution in capacity caused by the high-fat diet.

Implication. After different diets, it is unsatisfactory to rely on athletes' opinions about how they feel and use those perceptions as indicators of their work capacities. Work capacity is reduced significantly after a pre-exercise high-fat diet.

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