Fueling Your Workouts the Right Way at the Right Time

Health Professional, Medical Reviewer

We’ve discussed the best foods to eat before and after exercise. Now let’s discuss which foods to avoid because they could harm your workout.

Carbonated and high-sugar beverages

woman energy drink

Credit: Thinkstock

Drinking these beverages prior to exercise can lead to an upset stomach, bloating, gas, and acid reflux. If you need a caffeine boost prior to an early morning workout, try coffee or black or green tea. Don’t add excessive amounts of cream or sugar to avoid any gastrointestinal distress.

High-fiber foods

woman raw vegetables

Since fiber takes your body a long time to digest, avoiding these foods prior to your workout can decrease your risk of bloating or cramping during exercise. Avoid raw vegetables, particularly broccoli, peppers, cabbage, lettuce, cauliflower, and Brussels sprouts. Also avoid nuts, seeds, high-fiber bread, beans, and bean dips such as hummus for at least two hours both before and after exercise.

High-fat foods

high fat food

Dietary fat isn’t converted into energy as efficiently as the carbohydrates and protein that we eat. For this reason, eating high-fat foods prior to exercise can make you feel sluggish and tired during your workout.

High-protein shakes and bars

protein shake

While many people think that consuming these products prior to a workout will aid them in muscle building and repair, many high-protein shakes and bars do not contain enough carbohydrates to help you sustain your workout. They also take longer to digest, and may make your stomach feel uncomfortable during physical activity. A good rule of thumb is to look for a shake or bar that contains an equal amount of protein and sugar.

High sodium foods

added salt

Foods high in salt, such as packaged snacks and chips, can compromise your body’s fluid balance, which is crucial for exercise. Stick with foods that are homemade or fresh to limit your sodium intake prior to exercise.

Spicy foods


Many people think that consuming spicy foods will help them burn additional calories during exercise. While there is a modest increase in your body’s metabolic rate after consumption of spicy foods, eating them prior to exercise will not help you burn more calories during physical activity. Spicy foods can also lead to heartburn during exercise.

Energy gels

runner energy gel packets

Energy gels consist of a concentrated source of simple carbohydrate that should only be consumed during endurance activities lasting longer than an hour. Consuming these simple sugars prior to exercise will not enhance your performance, they merely provide additional calories.

Fueling for an endurance event

If you are preparing for a competitive event such as a running race or triathlon, experiment with food sources of fuel at least six weeks before your event to evaluate your tolerance to various foods. No two athletes are alike, so it is important to experiment with various fuel sources to evaluate what your body tolerates best both before and after exercise.

The evening before your event, consume a carbohydrate-rich meal that consists of at least 50 percent of the calories coming from high-quality complex carbohydrates, such as fresh fruit, vegetables, whole grains, oats, sweet potatoes, or brown rice. This will ensure that your body’s glycogen stores are adequate to support your endurance event. The day of the event, consume an easy-to-digest, carbohydrate rich snack to top off your body’s glycogen stores. Avoid high-fiber foods at least two hours before the event.

If your event is less than one hour in length, there is no need to refuel during the event. If it is greater than one hour, you will need to refuel every 20 to 30 minutes. During the event, use simple carbohydrates to refuel, such as Gatorade, fruit juice, or bananas. Remember to continuously hydrate your body with water during the event.

After the event, it is important to refuel your body within 60 minutes. During this “golden window” of time, your body is the most efficient at utilizing nutrients to help build and repair muscle tissue for recovery.

The bottom line

Proper nutrition and timing of meals is an essential component of maximizing the success of your workouts. If you struggle with your diet, food preparation, or managing your weight, consider seeking the advice of a registered dietitian to help you achieve your weight loss and fitness goals.

See More Helpful Articles:

The Best Pre-Workout Fuel

The Best Post-Workout Fuel

The Best High-Protein Snacks

Carmen is a registered dietitian who specializes in weight management and nutrition therapy for chronic disease. In addition to nutrition counseling at Johns Hopkins in Baltimore, Carmen teaches undergraduate health and wellness courses and provides corporate wellness seminars on exercise and nutrition.