High Fat Diets and Exercise Performance

High-fat diets may impact short-term memory, exercise endurance

Adding to a body of research that has associated long-term consumption of a high-fat diet with decline in cognitive function—as well as weight gain and heart disease—a study published in The FASEB Journal finds that eating fatty foods may have an almost immediate detrimental effect on short-term memory and exercise performance.

For the study—which was funded by the British Heart Foundation, and led by a researcher then at the University of Oxford in the United Kingdom—a research team fed 42 rats a low-fat rat-food diet in which just 7.5% of the calories came from fat and trained them for two months to complete a challenging maze and run on a treadmill. The researchers then switched half of the rats to a high-fat diet in which 55% of the calories came from fat. Comparing the cognitive performance and endurance of the rats for five days—after letting the rats eating the high-fat food get acclimated for four days—the researchers found that the rats on the high-fat diet made mistakes sooner in the maze task than the rats on the low-fat diet. Specifically, the rats on the number of correct decisions before making a mistake in the maze dropped from more than six in the low-fat diet cohort to an average of five to 5.5 in the high-fat diet cohort. Additionally, the rats eating the high-fat diet ran 30% less distance on the treadmill than rats on the low-fat diet on day five of the diet and 50% less distance on the ninth day of the high-fat diet. The researchers also found that rats on the high-fat diet had increased levels of a protein that interferes with the process of energy creation in cells—thus reducing the efficiency of the heart and muscles—and that, after nine days, the rats eating high-fat food had significantly bigger hearts than those eating low-fat food.

According to the researchers, the findings of similar studies performed on humans—which are still being reviewed—appear to have similar short-term effects. In addition to helping to inform athletes of the optimal diets for training regimens, the researchers suggest that the findings may help develop ideal diets for patients with metabolic disorders such as diabetes and patients who are obese, among others (Murray et al. The FASEB Journal, 8/10 [subscription required]; Parker-Pope, New York Times Well Blog, 8/13; University of Cambridge release, 8/11).