Final answer:
Nutrients are essential substances that the body needs for energy, building materials, and regulating body processes, divided into macronutrients (carbohydrates, proteins, lipids, and water) and micronutrients (vitamins and minerals).
Step-by-step explanation:
Nutrients are defined as substances needed for body function and essential for life. There are six major classes of nutrients: carbohydrates, proteins, lipids (fats), water, vitamins, and minerals. The body uses these for energy, building materials, and regulating body processes. Macronutrients, which include carbohydrates, proteins, and lipids, are needed in larger amounts and are vital as energy sources and for body structure. Water is also a macronutrient, but unlike the others, it doesn't provide calories. Micronutrients, comprising vitamins and minerals, are required in smaller quantities, playing crucial roles in various body functions, but do not yield energy like macronutrients.
Macronutrients are not confined solely to energy provision; they perform a variety of functions in the body. For example, protein is essential for tissue repair and growth, while fats provide cushioning and insulation, in addition to energy storage. Understanding the distinct roles of macronutrients and micronutrients is key to grasping the essentials of nutrition.