A balanced diet consists of eating a variety of foods to meet all the body's nutrient needs. There are six main nutrient groups - proteins, carbohydrates, fats, mineral salts, vitamins, and water. It is important to consume the right balance and proportions of calories from carbohydrates, fats, and proteins. The number of daily calories needed varies by age, gender, and activity level. Maintaining a balanced diet and calorie intake helps ensure the body's nutrient needs are met and limits are not exceeded.