“Start fueling early. You’ll want to start taking in fuel within the first 30 to 45 minutes and possibly even sooner. The goal is to consume 30 to 90 grams of carbs per hour to maximize your energy output. When running for less than 2.5 hours, 30 to 60 grams of carbs per hour is sufficient. If running longer than 2.5 hours, you will benefit from even more carbohydrates,” says Baumann.