Think you need extra carbs in a 2+ hour workout to keep from bonking? Think again. When your body burns through its carbohydrate storage, fat is used as fuel—which means, because fats burn slower than carbs, that your pace and intensity decreases. If you’re in the middle of an all-out marathon or intense tri, you’ve hit the wall and should have given your body some additional fuel. But races are not training!
You only need additional fuel for long and intense training days. If you’re going on a long aerobic ride, hike, workout, or run, burning fat as fuel is just fine. Your body doesn’t need more than a few dozen calories of carbohydrates (or any, really) to efficiently burn fat and keep you going.
—Ben Greenfield is an Ironman, coach, writer and triathlete who focuses on nutrition and physiology of endurance and multi-sport athletes. He was recognized as Personal Trainer of the Year in 2008 by the National Strength and Conditioning Association and is a member of Team Timex Multisport. Check out his eBook, Endurance Planet’s Guide To Sports Nutrition with Ben Greenfield: 20 Fueling Myths Exposed, and his website, BenGreenfieldFitness.com.