What to Eat for Exercise

In order to plan your pre-workout meals to attain a specific fitness goal, it is important to understand how the body utilizes different sources of energy during exercise:

Carbohydrates

This is the first energy source that the body utilizes during exercise. The body utilizes glucose (sugar molecules) from carbohydrates and stores excess sugar molecules as glycogen for future use. Simple carbohydrates, such as candy, enter the bloodstream very quickly and result in an immediate energy high and then crash. Complex carbohydrates, such as whole grains, are slowly metabolized so you have a longer sustained energy boost.

Fat

After the carbs (or sugar) have been used up, fat is the next energy source that the body utilizes in exercise. In order to start burning body fat, you must first burn off all of the available carbohydrates it has stored.

Therefore, if your goal is to burn fat during exercise, you either have to exercise for a longer period of time, in order use up all of the carbs and tap into fat stores, or you should eat less before a workout. For most people, there is no need to “carb-up” before a workout or race unless you are working out for an extended period of time and need the sustained energy. For me, I typically don’t need to eat anything before a long run as long as it is 10 miles or less. For my half-marathons, I would eat a banana and half a Clif bar an hour or two before the race and that would be enough for me. Then I would eat a larger meal about an hour after the race to replenish lost calories.

Protein

The last energy source the body utilizes after carbs and fat is protein. As a result, the body rarely burns protein unless the body is in conditions of starvation.

People tend to think that protein is the main source of energy needed for exercise, which is why they eat a lot of meat or take protein powders before a workout. I constantly get questioned about being a vegan and how I have the energy to work out, but I am the only person I know that works out 6-7 times a week doing strenuous interval training, cardio, and weight training. As you can see, carbohydrates, not protein, are the main energy source utilized by the body for energy so it is important to eat more complex carbohydrates, such as fruits and vegetables, if you want sustained energy for your workouts.

I think each person is different when it comes to pre-workout meals. I don’t like to eat anything before I work out. This is partially to do with the fact that I workout very early in the morning, around 5 am and don’t feel hungry at that time. I also prefer having an empty stomach when working out because I do a lot of sprinting, jumping, etc. and I don’t want a bunch of food sloshing around in my belly. In general, I think you should do what feels best for you. If you feel lethargic in the morning before you eat breakfast, you may want to grab something to eat before heading to the gym so you have more energy while you’re working out. If you generally workout in the afternoon, time your lunch so that you don’t eat a huge meal later in the day that will make you feel full during your workout. If you are planning on going on a long run or other endurance exercise, try not to eat too much beforehand because this will upset your stomach. You may have to try out a couple things to gauge how your body reacts and feels before you figure out what works best for you.