By Charles Davidson for Stronger Together

Whether you’re training for a marathon or you just exercise to stay fit, it’s important to remember that the human body, like any engine, needs fuel to maintain performance. But not all foods are created equal, and it’s important to eat the right kinds of foods whatever your fitness goals.

For aerobic training (any prolonged activity like running, biking, or swimming), the body’s main source of fuel comes in the form of carbohydrates. Carbs have received some bad press in recent years, but they are the key resource for maintaining any fitness regimen. It’s true that simple carbs like white bread and pasta, candy, and white rice won’t give you any prolonged benefit; they’re used up too quickly and are poor in nutrients. Eat them only immediately after a workout, if at all. But complex carbs, such as whole grains, provide lasting energy and nutrition.

Every time you work out, you’re actually breaking down your muscles. Ultimately, you build them up as they repair, and for this you need protein. Red meat is often high in saturated fat and hard to digest, making it difficult for your body to use the meat for muscle repair. You should look for lean meats and other proteins: chicken (especially white meat) and fish (which is also rich in omega-3 fatty acids), as well as protein-rich quinoa, beans, and tofu.

Whenever your muscles or tissues break down, your body generates “free radicals” that can be harmful over time. It’s important to keep your diet high in antioxidants, which will “scavenge” free radicals. Luckily, there’s a huge variety of antioxidant-rich foods, including veggies, fruits, nuts, seeds, and even red wine. Your local food co-op staff should be able to direct you to the freshest foods high in antioxidants.

And as for what to drink before, during, and after a workout, make it water—and plenty of it. The amount you’ll need will vary depending on factors like heat, body weight, and the intensity of your workout. Stay away from juice and soda, which are high in empty calories, and keep alcohol consumption to a minimum. Coffee, tea, and other caffeinated drinks are okay in moderation, as long as they don’t upset your stomach during workouts. After you exercise, an occasional sport drink or fruit juice is fine for immediate recovery, but don’t overdo it.

How to pack all this nutrition into your daily diet? Eat several small meals to help you maintain energy during your workout and throughout the day. Try to space them out, and snack if you need to. Your co-op staff will be able to point you toward healthy, nutritious snacks that you can enjoy and feel good about.