Are Low-Fat Diets Right for Runners?

If you're thinking about or already training to run or race-walk in the Bolder Boulder next month, or perhaps planning to do a longer race event this summer, don't forget diet as part of your pre-event preparations.

And don't be misled into thinking that going low fat is the nutritional pathway to the finish line.

Researchers at the University at Buffalo have showed that trained athletes who eat a very-low-fat diet may be hindering their performance. When 25 long-distance runners were put on a diet of 15 percent fat, they didn't have enough calories to meet the energy needs of their training regimen, and their HDL cholesterol levels went down, indicating implications for cardiovascular risk factors.

But when they went on a diet of 30 percent fat - considered a moderate amount and what is recommended for the average person - their endurance time increased and they had more muscle strength after an exhausting run.

Only half the people in the study were able to raise their dietary fat to the 45-percent level, but their endurance time went up a similar amount. Their levels of lactic acid were even lower than those on the low- or medium-fat diets, indicating an increase in energy reserve and more efficient energy metabolism, said the researchers.

Contrary to what athletes might fear, their measurements of body fat, total cholesterol, blood pressure and heart rate didn't go up when they started consuming more fat; in fact, all levels stayed the same.

"The distance runners in this study didn't have any negative effects on performance, nutrition or health on the high-fat diet," said Peter Horvath, an associate professor of nutrition and a lead researcher.

"If you want the calories necessary to do high-intensity training, you need to liberate yourself from a low-fat diet," he said.

The study applied to men and women ages 18 to 53 who ran an average of 40 miles a week. Before the study, the runners, on average, ate diets consisting of about 20 percent fat.

An additional study at the University at Buffalo showed that competitive distance runners who insist on a very-low-fat diet also may compromise their ability to ward off infection. Those on a 15 percent diet had fewer white blood cells, or leukocytes, the body's infection fighters, than did runners who spent a month on a moderate-fat (30 percent) diet.