By Llee Sivitz
Enquirer contributor

Think all you need to do to get fit is exercise? There's another side to the "fitness" coin. It's nutrition.

Fit City details

According to the dictionary, "nutrition" means consuming foods that promote growth and repair or replace worn, injured tissues.

But how does nutrition affect our workouts?

"You want to make sure you have the right balance of nutrients - proteins, carbohydrates and fats," says Jane Boback, a community dietician with the Nutrition Council in Mount Auburn. "If not, you won't have enough energy to be at your peak performance. And if you consume too much, you are going to feel sluggish."

Carbohydrates are the main source of energy for the body. During exercise the body uses carbohydrates stored in muscle (as glycogen) for fuel. A lack of carbohydrates in the diet depletes glycogen stores, which can lead to premature workout fatigue.

To maximize your glycogen, eat a high-carbohydrate diet - about 60 percent of your total calories each day.

"When you sit down to eat, about half of your plate should be carbohydrate-rich (whole grains, vegetables, fruit)," Boback says.

Surprisingly, fat is the next essential nutrient group - it should be 25 percent to 30 percent of your daily calories. Fat is needed for healthy tissues, and extremely low-fat diets are not recommended.

Nevertheless, you should limit saturated fat - found in high-fat dairy products and fatty cuts of meats, Boback says.

Protein, essential to repairing muscle, weighs in at only 15 percent to 20 percent of total daily calories (about 5 to 6 ounces of meat a day).

"Unless you are a body builder," Boback says. "Then your protein needs would increase."

When you eat can affect workouts as well.

Boback recommends that an hour before exercise you eat something that is going to help sustain you during the workout.

"Don't eat a big meal before you exercise because that will bog you down," she says. "But you can eat complex carbohydrates (such as a bagel, fruit or diluted fruit juice) rather than real simple sugars (such as candy), which might cause stomach upset."

Foods high in fat are not recommended for up to three hours before exercising.

After exercising, make sure you have adequate protein intake to help repair your muscles. Here's where a good protein source, such as peanut butter or a hamburger, can help.

Eating frequent, smaller meals may be the answer for those who need to exercise at night.

"Eat a small dinner and then after the workout, eat another snack," Boback suggests.

Most people experience an increase in appetite when they start an exercise program. This can be discouraging for those who are exercising to lose weight.

Boback's advice: "Make sure your food choices are healthy ones, such as eating more fruits and vegetables, or whole grains. It's OK to increase the volume of food you are eating as long as it is healthy."

So how do you lose weight on an exercise program?

"I've worked on weight-loss studies and I really feel that it's calories in versus calories out," says Boback. "And make sure the calories that you take in count as nutrient-dense, (rather than) junk food or empty calories."

Is there a way to eat that will increase metabolism and, therefore, burn more calories?

"No," Boback says. "The only way to increase your metabolism is to increase your muscle mass through a strength-training program (not cardiovascular exercise). Muscle is going to burn more calories than body fat does."