What you eat before and after you work out, may be the key to reaching a personal best - Jenna Blumenfeld No matter what you're training for - a half marathon or to stay in shape - what you eat before and immediately after your workout is almost as important as the workout itself. "If you work out for longer than an hour, you're likely running low on stored glycogen, the carbohydrate that fuels muscle contractions, " says Mary Jane Detroyer, RD, an exercise physiologist and personal trainer based in New York City. Here's what to eat before and after your one-hour (or longer) workouts to reach your fitness goals. Before Why: Eating 150 to 200 calories before an hour-long exercise session won't make you gain weight. Rather, a small snack allows you to increase the intensity of your run, ride, hike or fitness class - and in turn, helps you burn more calories than you would if you were under-fueled. "You want a snack to last throughout the duration of your workout, so you can finish it strong," says Detroyer. The Details: Thirty to 60 minutes before exercise eat a light "mini-meal" that includes carbohydrate, protein , fiber and a small amount of fat. Try: 1 stick string cheese with 3 whole-wheat crackers; 1 cup butternut squash soup with ½ tablespoon olive oil; ½ cup whole-grain cereal with ½ cup milk and 3 strawberries, sliced. After Why: Following a workout, your muscles are most receptive to absorbing glycogen. "If you don't get that post-workout snack in, you'll be fatigued the next day, and your next exercise will suffer," says Detroyer. "Without a snack, you won't be able to correctly recover and get stronger." The Details: Within 20 minutes after your workout is complete, replenish your muscles with foods or beverages that deliver 150 to 200 calories and contain a carbohydrate to protein ratio of 4:1. Including ample protein in meals is a typically good idea because it keeps you full longer, but in this case you want an easily digestible carbohydrate that your muscles can quickly absorb, explains Detroyer. Try: 1 cup nonfat chocolate milk; 1 small baked sweet potato topped with a dollop of plain yogurt; ½ peanut butter and jelly sandwich on wheat bread.