Every morning, noon and night, in gyms across America, you can hear the sound of a low but persistent rumble. Listen carefully and, in between the whir of the treadmill and the clank of weight plates, your ears will pick it up: the clamor of empty stomachs crying out for food.
Some people just don't have time to eat in reasonable proximity to their workout, but others deliberately go without food. One of the common misconceptions that people trying to lose weight have is that exercising on an empty stomach burns more fat than exercising after eating. They believe that if no food is available as fuel, their body will tap into its fat reserves.
Well, yes ... but there's a whole lot more to the story than that. As it turns out, if your goal is to maximize your workout and get (or maintain) a lean body, eating, not starving, is your best strategy. Here's what you need to know to prevent the empty stomach blues.
HOW FOOD FUELS YOU
Although your body burns some stored fat when you exercise, its main fuel is carbohydrate that's been stored in the muscles and liver in the form of glycogen. When your glycogen stores are depleted, your body will indeed tap more of its fat reserves--but at what price? Without readily available fuel, you're not likely to feel too energetic. If you can’t get the enthusiasm together to push through your workout, you won’t burn anything. On the other hand, if you eat before exercise, whether it's a large meal several hours in advance or a small snack only minutes ahead of time, you'll have the extra oomph you need for an energetic and effective workout.
Here's the reason: Before carbohydrates are tucked away in your muscles and liver as glycogen, it enters your bloodstream in the form of glucose (also called blood sugar), a readily available source of energy that helps perk you up when you're feeling hungry and fatigued. If the glycogen stored in your muscles and liver is low, your body can rely on glucose for fuel; if you already have a fair amount of stored glycogen, your body will use the glucose as a secondary source of energy and spare the glycogen. This means that you have two sources of fuel instead of just one, and can generally push harder and longer during a workout.
Something else you should consider is that the muscles and liver can only store so much glycogen. It's important to "top off" your reserves fairly often, even if you haven't been doing much: During a long night's sleep, the body depletes as much as 80 percent of the glycogen stored in the liver. Essentially your body has been fasting for for eight hours and needs to be refueled. That's why eating a little something before you exercise in the morning can really help. Moreover, it doesn't take long to deplete stored glycogen during exercise, and it gets used up even faster when the weather is warm. For example, if you are playing a relatively intense match of tennis outside, it may take as little as 30 minutes before you deplete your glycogen. Eating before a match will not only help you last longer, it will also help settle the gastric juices that make your stomach growl and ward off the feelings of lightheadedness and fatigue that can make it difficult to perform well.
WHAT TO EAT WHEN
Naturally, the fact that you shouldn't exercise on an empty stomach doesn't mean that you should eat a three-course meal 10 minutes before hitting the gym. In general, the closer you get to your workout start time, the fewer calories you should eat. The nutrients that make up those calories should also shift. Because it takes the body four to six hours to digest fat, about three hours to digest protein and about two hours to digest carbohydrates, it's important to winnow down the protein and fat content of your meal or snack as you get closer to exercise. You're not going to want to eat a plate of french fries two hours before working out, because the blood is going to rush to your stomach to digest that while it's also trying to rush to your exercising muscles. In the end, it doesn't do a very good job of either one.
So, here are a few rules of thumb to follow: If your workout is four hours away, eat a regular meal that combines protein, fat and carbohydrates, then have a small carbohydrate-rich snack closer to your exercise session to tide you over. Three hours before working out, make it a smaller meal and lighten up a bit on the protein and fat. Thirty to 90 minutes before exercise, have a snack of easily digested carbohydrates (see below). If you only have the 15 minutes between, say, leaving your office and hitting the gym to grab something, go for a few Saltines. Also keep in mind that while eating high-fiber foods is important for good health, they're best eaten after or long before exercise, since they can cause bloating and other annoyances that will make you feel uncomfortable when working out.
Finally, be aware that finding what works perfectly for you might take some trial and error. Some people find that certain foods and beverages eaten close to exercise are troublesome, while others find that they can eat a big meal and work out an hour later with no problem at all. So do a little experimenting, but at least (and we hate to sound like your mother) eat something!
PRE-EXERCISE NIBBLES TO KEEP YOU FROM RUNNING ON EMPTY
Depending on what time of day you'll be working out, consider these small snacks, which can be eaten 30 to 90 minutes before exercise (or closer if you can stomach it).
- 6 ounces orange juice
- 1 small banana
- Toasted English muffin spread with 2 tsp. strawberry jam
- 1 cup nonfat or low-fat yogurt
- 8-ounce fruit smoothie
- 12-ounce nonfat latte
- Small chocolate biscotti
- 1 ounce Goldfish crackers
- 4 cinnamon graham cracker squares
- 8 animal crackers
- 6 ounces chocolate soymilk
- 1 ounce baked potato or tortilla chips