Is it better to eat before or after exercising? I've recently started a fitness program and am not sure which way is the best.

To eat or not to eat... this simple question has a simple yet complex answer. Both strategies (eating before and eating after exercise) are good for performance, fitness, and health. However, how to eat for exercise is dependent on several factors, specifically, how long you exercise, your type of exercise, your exercise experience, and health factors that may play a role in how you process food. Nutrition plays a key role in building fitness, that's for sure.

Let's start with eating before exercise. What you choose to eat before you exercise can make or break your workout. Food is fuel, and it's important to eat at least something prior to a workout. Eating before exercise serves several functions:

1. fuels your muscles (both with food eaten in the days before as well as the hour or two before)
2. helps settle your stomach and avoid hunger
3. helps prevent low blood sugar (hypoglycemia) — symptoms can include dizziness, nausea, and headaches
4. fortifies your mental state by knowing that your body is fueled

What and how much you eat vary from person to person and sport to sport, with no right or wrong choice. The way to learn how much and what to eat is to experiment to see what works for you. Your food preferences may vary with the time of day, type of exercise, and level of exercise intensity. Consider the following guidelines:

Eat a balanced diet every day so your body is fueled and ready for action.

A balanced diet means incorporating a variety of wholesome foods into your daily choices. Good nutrition means eating sources of carbohydrates, protein, fats, vitamins/minerals, and water. The first three (carbs, protein, and fat) are sources of energy. Carbohydrates are a source of instant energy, proteins build and repair muscle, and fats are a source of long term energy. Choose foods such as fruits and vegetables, whole grain breads, pasta, chicken, fish, and/or tofu, peanuts, etc. For more information on nutrients and food choices, visit the American Dietetic Association web site.

Maintaining healthy nutrition is important for exercise because your muscles rely heavily on the foods, and primarily the carbohydrates, you eat daily. Your body digests carbohydrates into glucose (simple sugar), and either uses it for energy or stores it for later use. Extra glucose is stored mostly in the form of muscle glycogen (complex sugar). When you exercise, your body uses both glucose (quick, simple sugars) and glycogen (longer lasting, complex sugars). You'll notice a big difference in the way you feel if you spend days eating wholesome food versus foods that are fried and/or high in saturated fat or sugar. Remember, food is your fuel.

Allow enough time to digest.

Allow 3 - 4 hours for a big meal to digest, 2 - 3 hours for a small meal, and an hour or less for a small snack, depending on your body.

Avoid high fat proteins.

Peanut butter, red meat, and cheese, for example, take longer to digest and often add to feelings of fatigue.

Eat for the duration of your workout.

If you are going to exercise for less than an hour, you'll simply need foods that digest easily. Choose high-carb, low fat foods, such as crackers, bagels, or bread. If you are going to exercise for longer than an hour, choose carbohydrates that last longer, such as yogurt or a banana.

Drink plenty of fluids.

Dehydration is a common source of an unpleasant workout.

(Adapted from Nancy Clark's Sports Nutrition Guidebook, 1997)

Many people choose not to eat before exercise because they worry that they'll feel sluggish, have cramps or diarrhea, and/or experience an upset stomach. According to Nancy Clark, M.S., R.D., a leading sports nutritionist, unpleasant stomach and GI (gastrointestinal) problems can occur, depending on several factors:

Type of sport

Runners or people who do running-type sports that jostle the body report more GI problems with pre-exercise food intake.

Training status

Unfit individuals who are starting up an exercise regimen say they experience GI problems more than experienced athletes. This speaks to the time it takes to teach your body how to eat and exercise.

Age

GI problems occur more in younger individuals that those who are veteran exercisers. Again, this speaks to experience and knowing what your body needs.

Gender

Women are more likely to experience GI troubles, especially during times of menstruation.

Emotional and mental stress

An individual with stress, tension, and/or anxiety may experience either accelerated or delayed digestion.

Exercise intensity

During an intense bout of exercise, blood shifts from the digestive track to the muscles, leaving less blood to aid in the digestive process. This can cause cramps and other types of GI problems.

Precompetition food intake

Eating too much high-fat and high-protein foods (such as bacon or a greasy cheeseburger) right before a workout can trigger GI problems.

Fiber

High fiber foods (such as bran cereal or apples) can create GI problems.

Caffeine and concentrated sugar solutions

Coffee, for example, can lead to "coffee stomach" as a result of too much caffeine, creating unwanted stomach distress and/or hyperactive bowels.

Level of hydration

If you are dehydrated, you may experience GI problems during your workout.

Hormonal changes that occur during exercise

Exercise causes a change in the hormones that regulate the digestive system, creating an open door to GI problems.

Morning exercisers are especially guilty of exercising on an empty stomach. If you hit the road without any breakfast, you'll be running on fumes, not fuel. It's like choosing not to put gas into your car before driving to work. A few gallons will get you farther than if your tank is on or below empty.

Now, about eating after exercise: if you are a competitive athlete, what you eat after a workout is just as important as what you eat leading up to a workout, because your body needs to recover and replace glycogen stores in time for the next workout. If you are a recreational exerciser and work out 2 - 3 times per week, you need not worry as much about post-exercise foods because your body will have enough time between workouts to recover. It's common not to want to eat after exercise, because you may not feel hungry and/or don't have time. Learning to eat right after a workout, though, has benefits.

Studies have shown that 15 - 60 minutes after a workout is the optimal time to eat carbohydrate rich foods and drinks (e.g., banana, bagel, orange juice) because that is when enzymes that make glycogen are most active and will most quickly replace depleted glycogen stores in the muscles. Protein also helps with recovery in that it repairs muscle and helps with glycogen replacement. Eat a few slices of turkey on a wheat bagel, or have a large glass of protein fortified milk. The most important nutritional strategy post workout, though, is fluid replacement. Drink water, juice, or carbohydrate rich sports drinks to replace what you sweat out.

If you aren't used to eating before or after exercise, remember that it's a learned behavior. You can train your body to do almost anything. Teaching your body how to use food for exercise is an important part of building your fitness. Building fitness takes time, and so does learning to eat properly. With practice and patience, you can reap the benefits of good nutrition for exercise.

Alice

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