Actually, the ABCs of nutrition are the CPFs: carbohydrates, proteins and fats. These are the three basic macronutrients that all foods are made of. Any of these nutrients can provide energy, but your body responds to them in different ways.
Foods contain micronutrients too, the vitamins and minerals essential to health and body processes. And finally, you need to understand the importance of water—not the kind you drink but the often-overlooked ingredient in food.
Most importantly, you need all to function well, whether you’re running a marathon or sitting through a lecture. To understand which foods you should eat for meals and snacks (yes, you should snack!), you need to know how your body uses the basic nutrients, where to find them and how to put them together each day.