The key to a successful and healthy lifestyle is not fad diets that may help you lose weight quick but do not promote your health. Maintaining a healthy nutritional diet along with exercise is the best way to shed pounds, help increase your fitness, all while working toward the prevention of disease. Exercise is only half of what you need toward physical fitness, and nutrition is the other half that helps you stay fit and healthy.

Use these guidelines to plan your healthy diet.

Description: Carbohydrates are your body's main energy source. Complex carbohydrates include legumes, grains, and starchy vegetables such as potatoes, peas and corn. Simple carbohydrates, also called sugars, are found mainly in fruits and milk, as well as in foods made with sugar, such as candy and other sweets.

Recommendation: Get 45 percent to 65 percent of your daily calories — at least 130 grams a day — from carbohydrates. Emphasize complex carbohydrates, especially from whole grains and beans, and nutrient-rich fruits and milk. Limit sugars from candy and other sweets.

Description: Cholesterol is vital to the structure and function of all your cells, but it's also the main substance in fatty deposits (plaques) that can develop in your arteries. Your body makes all of the cholesterol it needs for cell function. You get additional cholesterol by eating animal foods, such as meat, poultry, seafood, eggs, dairy products and butter.

Recommendation: Limit your intake of cholesterol to no more than 300 milligrams a day.

Description: Fats help your body absorb many essential vitamins, maintain the structure and function of cell membranes, and preserve the integrity of your immune system. But fat is a very concentrated energy source, providing twice as many calories per gram as carbohydrates and protein. And too much of certain types of fat — such as saturated fat and trans fat — can increase your blood cholesterol levels and your risk of coronary artery disease.

Recommendation: Limit fat to 20 percent to 35 percent of your daily calories. Emphasize fats from healthier sources, such as nuts and olive, canola and peanut oils.

Description: Saturated fat is most often found in animal products, such as red meat, poultry, butter and whole milk. Other foods high in saturated fat include coconut, palm and other tropical oils. Saturated fat is the main dietary culprit in raising your blood cholesterol and increasing your risk of coronary artery disease.

Recommendation: Limit your daily intake of saturated fat to no more than 10 percent of your total calories. For most women, this means no more than 20 grams a day, and for most men this means no more than 24 grams a day.

Description: Fiber is the part of plant foods that your body doesn't digest and absorb. There are two basic types: soluble and insoluble. Insoluble fiber adds bulk to your stool and can help prevent constipation. Vegetables, wheat bran and other whole grains are good sources of insoluble fiber. Soluble fiber may help improve your cholesterol and blood sugar levels. Oats, dried beans and some fruits, such as apples and oranges, are good sources of soluble fiber.

Recommendation: Women need 21 to 25 grams of fiber a day, and men need 30 to 38 grams of fiber a day.

Description: Protein is essential to human life. Your skin, bones, muscles and organ tissue all contain protein. It's found in your blood, hormones and enzymes too. Protein is found in many plant foods. It comes from animal sources as well. Legumes, poultry, seafood, meat, dairy products, nuts and seeds are your richest sources of protein.

Recommendation: Between 10 percent and 35 percent of your total daily calories — at least 46 grams a day for women and 56 grams a day for men — can come from protein.