How long to wait after eating to work out?

QUESTION: How long should I wait after eating to work out? I often ride or lift weights in the evenings after dinner, because that works best with my work schedule. – Rob F

RBR ANSWER:  The answer varies depending on what kind and intensity of exercise you are talking about. Some cyclists, for example, particularly when riding with others, will pedal to a distant restaurant, eat a lunch meal, and shortly thereafter remount their bikes and ride the same distance back to their starting point without any digestive distress. These rides, which typically might be 20 miles or more in each direction, are clearly exercise, but the focus, especially on the return journey, is not on setting land-speed records, but on riding a pace that permits conversation. 

Likewise, it probably won’t upset your stomach to go for a walk — even an extended one — soon after dining.

But assuming you have something more strenuous in mind, exercise that qualifies primarily as a vigorous workout or a competition — something that emphasizes performance as opposed to a social event with physical activity — there are some guidelines regarding how long to wait.

In broad terms, the bigger the meal, the longer should be the interval between eating and exercising. That translates to three to four hours after a full meal and 30 minutes to two hours after a smaller repast (with “smaller” being about the size of your fist, not a soccer ball).

But even then, the guidelines are not absolute. For one thing, we are not all the same; some of us process food faster than others and some of us may have more sensitive digestive systems. And the kind of food we eat pre-workout also makes a difference. In general, meals before intense exercise should focus on protein and carbohydrates rather than fats. Fats are not bad, and are an important part of a healthy diet, but fats process through the digestive system more slowly and don’t convert into energy as quickly as carbs do. 

The time you wait can also be affected by the type of carbs you ingest. Simple carbohydrates, such as those in fruits and sport drinks, digest quickly and convert to energy almost right away, but provide only short-term energy. Complex carbs, such as those in potatoes and pasta, don’t digest as quickly but provide longer-lasting energy. There is value in both types of carbs, but which ones you choose affect how quickly you may want to begin your workout.

So, for example, if you have three or four hours before you exercise, you could eat a meal of foods that provide lean protein and complex carbs, such as a turkey sandwich on whole grain bread, with a side of vegetables or a cheesy pasta dish with a side salad.

If you have less than two hours before your workout, eat a bowl of whole grain cereal with low-fat milk, or have an energy bar or a banana, or perhaps both.

If you feel the need to eat something right before you work out, go for foods intended for athletic endeavors, like gels and energy drinks that usually won’t upset your stomach while exercising.

If the exercise itself is limited to about an hour, you may not need to ingest anything further while engaged in it, but if your activity goes on longer than that, you’ll likely need to take in some more calories to keep your energy up. Here again, gels and sports drinks are a good choice. If your activity is hours long, you’ll also need to take in water, and, especially in hot weather, a salty food such as pretzels or pickles can help replace the salt lost through perspiration.

Here is some when-and-what-to-eat advice tailored to cycling … tailored to running … tailored to weight training.

Stan Purdum has ridden several long-distance bike trips, including an across-America ride recounted in his book Roll Around Heaven All Day, and a trek on U.S. 62, from Niagara Falls, New York, to El Paso, Texas, the subject of his book Playing in Traffic. Stan, a freelance writer and editor, lives in Ohio. See more at www.StanPurdum.com.