As a registered dietitian, I know how important healthful eating is to staying energized and avoiding a midday slump. Adding any kind of physical activity to the mix, whether it’s an endurance event like a half-marathon, or a Zumba class, makes healthful eating even more important. To gain some perspective on how to eat to optimize exercise performance without sacrificing nutrient intake and health, I spoke with renowned sports dietitian Nancy Clark, RD, author of Nancy Clark’s Food Guide for New Runners: Tips for Everyday Champions.

EZ: What’s the biggest nutrition mistake active people make?

NC: Skipping breakfast! When you don’t consume a morning meal, you hinder your workouts. You won’t be able to concentrate or be very efficient while you work and you may very well feel drained midday and beyond. When you do fuel up and have a high-energy breakfast, you’ll set yourself up for a better workout and a higher energy day.

EZ: So many people routinely skip breakfast. Why do you think that is, and what are some tips you can suggest to help overcome breakfast barriers?

NC: I’ve heard so many excuses from clients over the years about why they skip breakfast—they’re not hungry or they don’t have time to eat. I say if you’re not hungry for breakfast, it’s probably because you ate too much too late the night before. I like to tell clients to ‘eat by day and diet by night’—that is, consume more calories during the active part of their day, and taper intake when they move less. In these situations, I recommend having a smaller dinner or shrinking (or altogether skipping) those late-night snacks. Those who feel they have no time need to realize that breakfast does not have to mean a sit-down, cooked meal. Planning a breakfast-to-go the night before can save you time and provide you with energy and key nutrients you need to get through the day.

EZ: Can you recommend a few easy-to-prepare, high-energy breakfasts that one could eat before a morning workout?

NC: For morning exercisers, I recommend foods that provide carbohydrate and a little bit of protein both before exercise and afterward. These nutrients promptly provide fuel for the workout and, because recovery can start with the pre-exercise snack, the pre-exercise fuel puts in place the nutritional tools the muscles need afterwards: carbohydrates to replace diminished glycogen stores and protein to help heal muscles so they’ll be refreshed for the next training session. Here are a few examples: A bowl of whole grain, high-fiber cereal with nonfat milk; a bowl of oatmeal topped with raisins and chased with some nonfat milk; a whole wheat bagel or some whole grain toast topped with peanut butter and honey; a whole wheat pita stuffed with hummus, cottage cheese or sliced turkey; or even a baked potato with cottage cheese or nonfat yogurt topped with sliced fruit or berries and some sunflower seeds.

EZ: What’s your advice for those who skip breakfast to save calories and lose weight?

NC: Many people think that food is “fattening” and don’t want to eat very much so they can avoid calories and lose weight. But it’s crucial to be as nice to your body as you are to your car. That means, fueling up—especially in the morning—even if you want to lose weight. Food helps you get through your workout, and especially during endurance events, eating can add some enjoyment.

EZ: Any final advice for active women?