Although the main goal for many exercisers is to shed pounds, experts say intelligent pre- and post-workout snacking can actually be a fitness aid.
The primary goal of eating before a workout is to curb hunger and prevent gluconeogenesis, a condition that causes the body to break down muscle mass when it detects low blood sugar levels, said Gretchen Hammel, a registered dietitian at Sports Barn.
Pre-workout snacks should be high in carbohydrates, light on protein and eaten 60-90 minutes before the activity, she said. Leaving time for digestion is crucial, since that process stops during exercise as blood circulates away from the stomach to active muscle groups, Hammel said.
"At the 30-minute mark [before exercise], nothing should be going in your mouth that's high-fat or high-protein," she said. "It needs to be something high-carbohydrate, something that is easy to digest quickly, not something that is high in fiber."
While they are important to maintaining blood-sugar levels, not all carbohydrate-rich foods are created equally.
Mashed potatoes and white bread contain simple carbohydrates, which break down quickly, releasing energy into the body faster. Before working out, however, the complex carbohydrates in foods such as oatmeal, sweet potatoes and brown rice are more beneficial, said Colton Duncan, a fit coach at Rush Fitness downtown.
Because they digest more gradually, complex carbs provide energy at a steady, manageable pace, Duncan said.
"You need something ... that will be broken down in your body slower, as opposed to ... simple carbohydrates that break down fast and spike your insulin," he said. "You don't want that because it will give you a burst of energy and then you're done."
Choosing what to eat after a workout concludes largely depends on the intensity and duration of the workout as well as the participants long-term fitness goals, experts say.
Post-workout foods should replenish the stores of glycogen, the body's main source of energy storage besides body fat.
High-intensity activity over long periods, such as long-distance runs or weight training, burn through stores of glycogen. Failing to replenish that supply is like trying to drive on an empty gas tank, Hammel said.
"Right after a workout is when your muscles are trying to get the glycogen the most because they're depleted, so they're really trying to do everything they can to replete those muscles," she said. "You want to refuel those muscles right away.
"Fueling up the glycogen stores - filling up your muscle tanks - the faster the better because it will prevent soreness and make your muscles feel better and you'll recover faster."
Choosing the ideal post-workout snack is made easier thanks to the glycemic index, which measures how high and how quickly a food will raise blood-sugar levels.
The glycemic index is a system measuring how quickly and to what level the carbohydrates in food raise the body's blood glucose (blood sugar) level. Foods with lower scores will break down more gradually, and those with higher scores release glucose into the blood stream more rapidly.
Glycemic index scores are important for exercisers to know when choosing foods to consume before and after working out. Here are some examples of foods and their accompanying glycemic scores.
50-gram serving of mixed nuts and raisins (21)
60-gram serving of dried apricots (30)
60-gram serving of apples or oranges (40)
150-gram serving of steamed brown rice (50)
120-gram serving of ripe mango (60)
120-gram serving of bananas (70)
120-gram serving of watermelon (80)
To refill glycogen stores, registered dietitian Pam Kelle recommends choosing foods with higher glycemic indexes, which will break down more quickly and provide the glycogen lost during training.
Hammel said post-workout nutritional needs are best met by foods that contain carbohydrates and protein in a roughly 3:1 ratio. Trainers and coaches have discovered that the ideal combination of nutrients for post-workout recovery are found in surprising source: chocolate milk.
"It's just the perfect drink because it has the calcium and magnesium that have been lost through perspiration," she said. "It is in a nice bed of lactose, which is a carbohydrate, and protein to help with the glycogen store replacement."
Whatever exercisers choose to eat - or drink - the ideal window for doing so is within 2-3 hours of the completion of the exercise. After high-intensity activities, some people may experience a loss of appetite, but the body's needs make snacking too important to skip, Kelle said.
"Timing is extremely important to make sure they replenish the lost nutrients post-game or post-event," she said. "There is a two-hour window of opportunity to replace those lost nutrients."
Just like exercising itself, choosing a pre- and post-workout diet plan will depend on individual physiology and fitness level.
As a result, even something as simple as choosing an energy bar will depend on how the body reacts to it, said Teresa Wade, director of operations at the downtown Sports Barn.
"It's really individualized," she said. "I always tell people not to buy a case of [an energy bar], just buy one or two and see which one your body responds to the best. There's no such thing as a perfect food."