Eating a high-fat diet can gradually balloon your waistline, but it may also take a faster toll on your physical endurance and memory, according to British researchers.

A team led by Andrew Murray, a lecturer in physiology at Cambridge University in Britain, tested endurance and memory in 32 rats fed either a low-fat diet (7.5 percent of calories from fat) or high-fat rat chow (55 percent calories from fat).

A treadmill test gauged how long the rats could run before reaching fatigue. The rats were also trained to run an 8-armed maze to locate a tasty treat of sweetened condensed milk. To acquire the treats quickly, rats needed to remember which maze arms they had already visited.

The fatty rat chow appeared to act quickly. Within 5 days of being on the diet, rats could run 50 percent less before tiring. It also took them 25 percent longer to complete the maze because they made more mistakes in the process.

The rat study appeared online August 10, 2009, in The FASEB Journal, the journal of the Federation of American Societies for Experimental Biology. Preliminary results of studies on healthy young men also show reduced performance on high-fat diets.

The study may have implications for training of high-performing athletes. Murray and his colleagues have identified a biochemical mechanism that might explain the study findings on exercise performance.

A high-fat diet triggers release of proteins that make the conversion of food into energy less efficient. Athletes needing to go the distance might benefit more from fuel in the form of carbs, not fat. Studies like this one could help nutritionists to design higher-performing diets.

RESOURCES

• “Deterioration of physical performance and cognitive function in rats with short-term high-fat feeding,” by Andrew J. Murray and others. (The FASEB Journal, published online August 10, 2009.) Abstract available via PubMed.