Nutrition is the study of how the body uses food. Nutrients in food help maintain the body and support bodily functions like breathing. The six main classifications of nutrients are vitamins, minerals, water, protein, carbohydrates, and fats. Nutrients that provide calories are proteins, carbohydrates, and fats. The number of calories provided per gram differs between these nutrients. Factors like age, gender, activity level, climate, health, and nutritional state affect individual nutrient needs. The ten U.S. Dietary Guidelines aim to promote health and fitness through recommendations like maintaining a healthy weight, being physically active, choosing a variety of grains and fruits/vegetables, and moderating intake of sugars,