July 6, 2015 | 2 minute read

Q: I’ve heard that it’s important to have proper fuel and liquids before exercise. How do I get enough for good exercise without getting too many calories?

A: You’re right, food and fluid are important to get more out of your exercise and to feel better during and after. What and how much you need depend on how long and intense your activity is and whether you want to gain, maintain or lose weight. The key is to give your body what is right for you.

Water is the ideal beverage for most people. Drink enough before (and during) exercise to prevent dehydration, and then after to replace fluid lost in sweat. Most recreational athletes do well using thirst as a guide for how much to drink. For those exercising more than an hour or at high intensity, sports drinks supply carbohydrate for energy that’s easily digested during exercise, along with the electrolytes sodium and potassium.

You likely don’t need extra snacks for moderate activity of less than 60 minutes. If you exercise several hours after a meal and run out of energy without a snack, choose something that’s appropriate for your level of exercise. A piece of fruit might be all you need. Or you may do better with small amounts of carbohydrate plus a little protein; perhaps combining a couple of choices such as yogurt, cottage cheese, a small bowl of cereal, a handful of nuts or a piece of fruit. But if your goal is to avoid weight gain or even gradually lose weight, that can easily be sidetracked by snacks or drinks before or after exercise that supply more calories than you burn. Most people, for example, burn 100 to 200 calories in 30 minutes of brisk walking.

If you have diabetes and your medications put you at risk of hypoglycemia, you need to know when you need extra carbohydrate before exercise. Talk with your healthcare provider or diabetes educators about what’s right for you. However, many of today’s diabetes medications don’t pose that risk, so pre-fueling with extra carbohydrate can be counter-productive.

For suggestions on starting your day fueled for your workout, read Exercise and Breakfast.