Final answer:
Nutrients are the essential substances in food that provide energy, as well as materials for cellular development, growth, and repair. There are six main nutrient classes, with carbohydrates, protein, and fats being macronutrients needed for energy and structure, and vitamins and minerals being micronutrients for regulatory functions.
Step-by-step explanation:
The substances in foods that provide energy and materials for cell development, growth, and repair are called nutrients. These are vital for our bodies to function correctly and are found in varying forms within the foods we consume. There are six main classes of nutrients essential for the body: carbohydrates, protein, lipids (fats), vitamins, minerals, and water.
Macronutrients are the nutrients we need in larger quantities, including carbohydrates, protein, and fats. These substances serve as the primary energy source for our bodies and are necessary for the structure and functioning of cells. For instance, carbohydrates are used predominantly for energy, proteins for building and repairing tissues, and fats for energy storage and cell membrane composition. On the other hand, micronutrients, such as vitamins and minerals, are needed in smaller amounts but are crucial for regulating various body processes.