How Glycemic Index Affects What You Should Eat Before and During a Race

As the low-carb craze blurred into the no-processed-foods Paleo trend that only permits low-glycemic carbohydrates, many endurance athletes have had success dropping pounds on these types of diets, but are they ideal for optimal long-term training and racing?

Many recent diet trends demonize high-glycemic carbohydrates, such as refined sugars and processed carbs like white bread, but if you're an athlete who is currently training and racing, you need low-, medium- and high-glycemic carbs to power your efforts. The key is learning what you need when.

"There's evidence to show that out-of-shape, overweight people who eat a lot of high glycemic-index foods may be doing detrimental harm to their health, but athletes who don't have these health risks are well equipped to deal with a rapid rise in insulin," says Liz Applegate, Ph.D., director of sports nutrition at the University of California, Davis. "We're always consuming glucose [sugar, which is what the body converts carbs into], and that's what we need as fuel."

More: The New Rules of Marathon Nutrition: How Many Carbs?

Fuel Pre-Race or Workout With Low-Glycemic Foods

Applegate recommends that athletes eat a low-glycemic meal a few hours before their race or long training session so they'll start the hard effort with a steady stream of energy. She suggests oatmeal with an apple or pear. Your pre-race breakfast won't carry you all the way through a long effort like the marathon, but it will get you off to the right start. An hour to 30 minutes before the start, you can always top off your glycogen stores with a quick source of carbs such as a sports drink.

More: What to Eat Before a Run