Food is any material consumed to supply nutrition to an organisms. In humans, food is of three main types: solid, semi-solid, or liquid. Generally, food is of animal, plant or fungi origin, and has vital nutrients, including proteins, carbohydrates, vitamins, or iron, depending on its type.
One of the main functions of food is to supply energy to the living things that live by removing energy from the matter it is made up of. Humans require about 7 calories of food for every gram of body weight. The nutritional content of a human food can be determined in various ways. Some people may see food as the only means of getting all the nutrients they need, while other people believe in the power of ‘life nourishment’.
There are different groups of foods, like animal products, dairy products, poultry, fish, grains, vegetables, fruits, legumes, seeds, oils, potatoes, sugar and salt. In some cases, one food type is considered to be complete, i.e. complete with vitamins, minerals, protein, fat, carbohydrates and fiber, while other foods are grouped according to their protein sources and their carbohydrate sources. Fishes like cod, haddock, fish, striped bas, haddock, herring, cod and tuna and breads like whole-wheat, spelt and rye are examples of incomplete diets. Some plants, such as beans and spinach, contain complete proteins and minerals, but no vitamins and no fat.