What you eat before, during, and after a workout is called “fuel” for a reason. Just like gas for a car, it gives your body the energy it needs to get through a tough sweat sesh or endurance event. And you’ll want to stick to the premium stuff when it comes to long workouts: Fueling your body properly (with easy-to-digest fats, carbs, and proteins) makes a huge difference in your performance, says Ben Greenfield, C.S.C.S, sports nutritionist, and author of BeyondTraining: Mastering Endurance, Health & Life, (Greenfield is also an accomplished athlete: he competed in the IRONMAN World Championships in Kailua-Kona, Hawaii, this past last weekend.)
But fueling isn’t as simple as sticking to healthy foods and eating when you’re hungry, and so many athletes unwittingly make big nutritional mistakes that can ruin their workout—or even cost them a personal record during a race. Here, Greenfield outlines five of the most common fueling errors he sees endurance athletes make—and how to fix ‘em.
Mistake #1: You eat something new the day of a race or important workout
It’s smart to experiment with different foods to see how well you perform with various fuel sources. Just don’t do it the morning of (or even the day before) your event or an important workout—like that 20-miler on yourmarathon training plan.
Fix It: Decide what you’ll eat the morning of your big workout or race—and practice by eating it before shorter workouts at least four to six times. “That's how long it takes to train your gut to get used to the fuels you plan on using,” says Greenfield.
Mistake #2: You suck down too much caffeine beforehand
A cup of Joe can indeed enhance your performance: “Caffeine has been shown to improve endurance in cyclists and runners, and improve performance times and boost power in rowers,” says Greenfield. Plus, it can reduce your perceived exertion, which means you feel like you aren’t working as hard, he says. But overdo it and you increase the chances of negative side effects, like nervousness, insomnia, headaches, and digestive woes—all of which can impair your athletic performance or cause long-term adrenal issues, says Greenfield.
Fix It: Greenfield says sports nutrition guidelines recommend 0.5-1.5 mg of caffeine per pound of body weight (that’s 75-225 mg for a 150-pound woman). But he suggests sticking to the lower end of that range (70mg is about one cup of coffee).
Mistake #3: You eat a kale salad before an evening workout
We love kale, too, but since it’s packed with tough-to-digest fiber, it’s not a good choice right before your workout. “Fiber significantly slows gastric emptying, so consuming too much of the stuff before a workout results in a lot of undigested food in your stomach and intestine, which lead to bloating and gas during your workout,” says Greenfield. Not pleasant.
Fix It: Stick to easily digestible carbs like almond butter and honey or asweet potato with some sea salt. And if you must have fruits and veggies, try blending or juicing them, which helps to “pre-digest” the food so your stomach doesn’t have to work as hard, says Greenfield. “This frees up precious energy for your body to devote to breathing, moving, and contracting muscles,” says Greenfield. Just make sure to slurp it down two to three hours before start time so you can fully digest.
Mistake #4: You drink when you’re “supposed to” during your workout
If you ask three different experts how much you should drink during a workout lasting longer than an hour, you’ll probably get three different answers. But since everyone has different fueling needs, and there are variables like temperature and humidity, you may actually need more or less fluid than a boilerplate recommendation.
Fix It: Greenfield’s answer makes a lot of sense to us: Drink water when you’re thirsty, so long as you’re getting somewhere between 10 to 20 ounces per hour of your workout. “As long as you listen to your body, you will vastly reduce your risk of both over hydration (hyponatremia) and dehydration. The human body is an amazing machine, and your brain will let you know when to drink,” says Greenfield.
Mistake #5: You skip a post-workout snack
After you've finished exercising, one of your primary goals should be to restore your energy reserves with a good mix of protein and carbs as quickly as possible, says Greenfield.
Fix It: Try an easy-to-digest meal with a 3:1 ratio of carbs to protein, which research suggests is the ideal balance. Try fresh fruit and a handful of nuts, Greek yogurt with blueberries, or a whole-wheat wrap with almond butter and honey. If you tend not to be hungry right after a workout, try a protein shake or an energy supplement with recovery fuels such as X2Performance—for which Greenfield is a spokesperson—until you get your appetite back.