1. Water. Water is the most abundant compound in the body, making up about 60% of our weight. It is involved in many important bodily functions, including regulating body temperature, transporting nutrients and oxygen to cells, and removing waste products.

2. Proteins. Proteins are the building blocks of the body. They are involved in a wide range of functions, including muscle contraction, tissue repair, and immune response.

3. Carbohydrates. Carbohydrates are the body's primary source of energy. They are broken down into glucose, which is used by cells for energy production.