Proteins, fats and carbohydrates are complex substances that make up most of the mass of all living organisms. We cannot synthesize them from inorganic substances, and therefore we have to get them from food. Actually, they are valuable in nutrition because of their constituents - amino acids, simple sugars, fatty acids and alcohols. Amino acids are part of our own proteins - the most important compounds of the body, moreover, they can, sugars are used as a source of energy, and together with proteins they recognize other molecules (including pathogenic microbes and poisons), fats-lipids make up all membranes cells, are also precursors of vitamins, hormones, in many ways provide energy to the heart and brain.
Proteins, fats, carbohydrates are complex organic compounds. They are necessary for nutrition, growth of the body. Our entire body consists of protein. We are solid protein.
Carbohydrates are the fastest energy.
Fats play a huge role in hormones.