Running a Marathon? Load Up on Fat

New research suggests carb-loading before a race isn’t the best way to energize.

New research suggests that carb-loading before a race isn't the bets way to energize. Photograph courtesy of Shutterstock.

We’ve all heard this before: Before a race, load up on carbohydrates. It makes sense, since carbs are packed with energy, and we all know how much of that we need to run a marathon.

But results from a small study suggest that if you want to keep energy flowing, a carb-heavy meal isn’t necessarily the best thing to eat right before competition. In fact, the most beneficial meal is high in fat, not carbs.

For the study, eight male collegiate runners consumed high-carbohydrate meals (71 percent carbs, 19 percent fat, 10 percent protein) for three days leading up to their endurance test. Before the test, training was limited and performed at low intensity.

Four hours before the treadmill endurance test, the runners ate either a high-fat meal (55 percent fat) or a high-carb meal (70 percent carbs). In addition, three minutes before the test they either ingested a placebo jelly or a carbohydrate jelly, which has a higher rate of absorption than glucose and is typically found in sports drinks.

Each runner ran for 80 minutes on a treadmill at his marathon race pace. Then each ran until exhaustion at a speed that would deplete his glycogen levels. Runners were able to drink water during the test; the lab temperature was set at 68 degrees.

It turned out that when runners consumed a high-fat meal and carb jelly, their time to exhaustion increased significantly. Eating a high-fat meal and the placebo jelly also resulted in an improved running time over the high-carb meal, though not as long as the high-fat and carb jelly combination. These results occurred for seven of the eight runners.

Researchers determined that eating a high-fat meal before a race boosts one’s fat metabolism during exercise, allowing the body’s carbohydrate storage to be used later during a race. “Following three days of glycogen loading, a high-fat meal and subsequent ingestion of a small portion of carbohydrate jelly prior to exercise enhances the performance of athlete endurance training,” they said in the study.

The fully study is available in the journal Nutrients.