Healthy diets contain the amounts of essential nutrients and calories needed to prevent nutritional deficiencies and excesses. Healthy diets also provide the right balance of carbohydrate, fat, and protein to reduce risks for chronic diseases, and are a part of a full and productive lifestyle. Such diets are obtained from a variety of foods that are available, affordable, and enjoyable.

The Dietary Guidelines describe food choices that promote good health

The Dietary Guidelines are designed to help Americans choose diets that will meet nutrient requirements, promote health, support active lives, and reduce chronic disease risks. Certain diets raise risks for chronic diseases. Such diets are high in fat, saturated fat, cholesterol, and salt and they contain more calories than the body uses. They are also low in grain products, vegetables, fruit, and fiber.

Foods contain energy, nutrients, and other components that affect health

People require energy and certain other essential nutrients. These nutrients are essential because the body cannot make them and must obtain them from food. Essential nutrients include vitamins, minerals, certain amino acids, and certain fatty acids. Foods also contain other components such as fiber that are important for health. Although each of these food components has a specific function in the body, all of them together are required for overall health. People need calcium to build and maintain strong bones, for example, but many other nutrients also are involved.

The carbohydrates, fats, and proteins in food supply energy, is measured in calories. Carbohydrates and proteins provide about 4 calories per gram. Fat contributes more than twice as much -- about 9 calories per gram. Alcohol, although not a nutrient, also supplies energy -- about 7 calories per gram. Foods that are high in fat are also high in calories. However, many lowfat or nonfat foods can also be high in calories.