Nancy Clark, the director of nutrition services at SportsMedicine Associates, talks about the benefits of snacking for a workout.
Snacking before you exercise will help energize your workout. A preexercise snack has four main functions:
- To help prevent hypoglycemia (low blood sugar) with its symptoms of lightheadedness, needless fatigue, blurred vision, and indecisiveness’-all of which can interfere with top performance
- To help settle your stomach, absorb some of the gastric juices, and abate hunger
- To fuel your muscles, both with food eaten in advance that is stored as glycogen, and with food eaten within an hour of exercise
- To pacify your mind with the knowledge that your body is well fueled
Yet many people purposefully exercise on empty because they believe that exercising without having eaten beforehand enhances fat burning. True, but they assume that by burning more body fat, they will lose more body fat. False. To lose body fat, you need to create a calorie deficit by the end of the day. Whether you burn carbs or fats has less to do with losing body fat than it does with your calorie balance at the end of the day. The truth is you’ll be able to exercise harder and burn more calories if you eat a preexercise snack. The harder exercise might contribute to the desired calorie deficit.
Many people are also afraid that preexercise food will result in an upset stomach, diarrhea, and sluggish performance. Of course, too much of the wrong kinds of foods can cause intestinal problems, but lack of fuel is more often the cause of sluggish performance. Morning exercisers, in particular, need to be sure they have fueled themselves adequately, even if they work out before breakfast.
Snacks Before Morning Workouts
Skipping breakfast is a common practice among people who exercise in the morning. If you roll out of bed and eat nothing before you jump into the swimming pool, participate in a spinning class, or go for a run, you may be running on fumes. You will probably perform better if you eat something before you exercise. During the night, you can deplete your liver glycogen, the source of carbohydrates that maintains normal blood sugar levels. When you start a workout with low blood sugar, you fatigue earlier than you would have if you had eaten something.
How much one should eat varies from person to person, ranging from a few crackers to a slice of bread, a glass of juice, a bowl of cereal, or a whole breakfast. If you’ve had a large snack the night before, you’ll be less needy of early morning food. But if you’ve eaten nothing since a 6:00 P.M. dinner the night before, your blood sugar will definitely need a boost. Most people feel good results with 0.5 grams of carbohydrate (2 calories) per pound (1 gram per kilogram) of body weight one hour before moderately hard exercise, and 2 grams of carbohydrates (8 calories) per pound (4 grams per kilogram) of body weight four hours before-hand. For a 150-pound (68-kilogram) person this is 75 to 300 grams (300 to 1,200 calories) of carbohydrates-the equivalent of a small bowl of cereal with a banana to a big stack of pancakes (ACSM et al. 2000).
Defining the best amount of preexercise food is difficult because tolerances vary greatly from person to person. Some athletes get up an hour early just to eat and then go back to bed and allow time for the food to settle. Others have a few bites of a bagel, a banana, or some other easy-to-digest food as they dash out the door. Then there are those who habitually run on empty. If that’s you, an abstainer, here is a noteworthy study that might convince you to experiment with eating a morning snack before you work out.
Researchers asked a group of athletes to bike moderately hard for as long as they could. When they ate breakfast (400 calories of carbohydrates) 3 hours before the exercise test, they biked for 136 minutes, as compared with 109 minutes with only water (Schabort et al. 1999). Clearly, these athletes were able to train better with some gas in their tank. Preexercise morning fuel will likely work for you, too!
Four hundred calories is the equivalent of an average bowl of cereal with some milk and banana; it’s not a pile of pancakes. You need not eat tons of food to notice a benefit; some food is helpful but more food may not be better. Eat what’s comfortable for you and learn what is the right amount to fuel your workouts but still settle well.
Snacks Before Afternoon Workouts
Joe, an afternoon runner, wondered if eating a bagel at 3:00 would provide energy for his 4:00 workout or simply sit in his stomach. I explained that, despite popular belief, the food one eats before a workout is digested and used for fuel during exercise. The body can indeed digest food during exercise, as long as you are exercising at a pace you can maintain for more than 30 minutes. Cyclists who ate 300 calories before exercise absorbed all 300 calories during the hour of moderate to somewhat hard exercise (Sherman, Pedan, and Wright 1991).
If Joe were to do extremely intense sprint activity such as a track workout or time trial, the food would be more apt to sit in his stomach and talk back to him. During intense exercise the stomach shuts down so that more blood can flow to the muscles. Therefore, you need to plan your schedule and eat a hearty lunch at noon if you will be doing a hard workout at 4:00 (with no preexercise snack because of the intensity of the workout).
Here is a second study that demonstrates the importance of eating before you exercise. In this study cyclists ate either nothing or 1,200 calories of carbohydrates (two grams of carbohydrates per pound of body weight) four hours before an exercise test to exhaustion. When they ate the 1,200-calorie meal they were able to bike 15 percent harder during the last 45 minutes, as compared with when they ate nothing. Given that road races and many competitive events are won or lost by fractions of a second, to be 15 percent stronger offers a huge advantage (Sherman et al. 1989). The carbohydrates the cyclists ate before they exercised supplied extra fuel for the end of the workout, when their glycogen stores were low.
Although these studies looked at cyclists, who tend to report fewer gastrointestinal complaints than do athletes in running sports that jostle the stomach, the benefits are worth noting. If you’ve always exer-cised on an empty stomach, you may discover that you can exercise harder and longer with an energy booster. Experiment during training with eating some carbohydrate-based snacks within a few minutes to four hours before you exercise. If you swim at 6 A.M., munch on a bagel on the way to the pool. If you work out at lunch, be sure to eat carbs such as cereal for breakfast and a banana for a 10 A.M. snack. If you exercise after work, have a substantial lunch and then a yogurt and energy bar for a second lunch later that afternoon.
What’s the Best Time to Eat?
The trick to completing your workout with energy to spare is to fuel up at the right time before the event. Here are some suggestions for different types of events at different times of the day.
Time: 8 A.M. event, such as a road race or swim meet
Meals: Eat a high-carbohydrate dinner and drink extra water the day before. On the morning of the event, about 6:00 or 6:30, have a light 200- to 400-calorie meal (depending on your tolerance), such as yogurt and a banana or one or two energy bars, tea or coffee if you like, and extra water. Eat familiar foods. If you want a larger meal, consider getting up to eat by 5:00 or 6:00.
Time: 10 A.M. event, such as a bike race or soccer game
Meals: Eat a high-carbohydrate dinner and drink extra water the day before. On the morning of the event, eat a familiar breakfast by 7:00 to allow three hours for the food to digest. This meal will prevent the fatigue that results from low blood sugar. If your body cannot handle any breakfast, eat a late snack before going to bed the night before. The snack will help boost liver glycogen stores and prevent low blood sugar the next morning.
Time: 2 P.M. event, such as a football or lacrosse game
Meals: An afternoon game allows time for you to have either a big, high-carbohydrate breakfast and a light lunch or a substantial brunch by 10:00, allowing four hours for digestion time. As always, eat a high-carbohydrate -dinner the night before and drink extra fluids the day before and up to noon.
Time: 8 P.M. event, such as a basketball game
Meals: You can thoroughly digest a hefty, high-carbohydrate breakfast and lunch by evening. Plan for dinner, as tolerated, by 5:00 or have a lighter meal between 6:00 and 7:00. Drink extra fluids all day.
Time: All-day event, such as a hike, 100-mile bike ride, or triathlon training
Meals: Two days before the event, cut back on your exercise. Take a rest day the day before to allow your muscles the chance to replace depleted glycogen stores. Eat carbohydrate-rich meals at breakfast, lunch, and dinner (see chapter 7 for information about carbo loading). Drink extra fluids. On the day of the event, eat a tried and true breakfast depending on your tolerance.
While exercising, at least every 1 1/2 to 2 hours plan to eat carbohydrate-based foods (energy bars, dried fruit, sports drinks) to maintain normal blood sugar. If you stop at lunchtime, eat a comfortable meal, but in general try to distribute your calories evenly throughout the day. Drink fluids before you get thirsty; you should need to urinate at least three times throughout the day.