ABSTRACT

Water makes up about 90 percent of blood plasma, about 70 percent of muscle, brain tissue and skin, 20–30 percent of fat tissue, about 20 percent of bones and fifteen percent of teeth. Generally, a man’s body has about ten percent more water than a woman’s because of a higher percentage of lean tissue. Energy, in a nutritional sense, refers to the fuel that can be burnt in the body to release energy for the body’s functions, rather than the feeling of being energetic. Solar energy is captured by plants and used for making protein, carbohydrates and fats, and animals obtain their energy from eating these macronutrients in plants or the tissues of other animals. The required amounts of kilojoules derived from protein, carbohydrate and fat in the diet vary according to individual needs, and are usually expressed as a percentage of the total kilojoules in the diet.