A negative-calorie food is food that supposedly requires more food energy to be digested than the food provides. Its thermic effect or specific dynamic action – the caloric "cost" of digesting the food – would be greater than its food energy content. Despite its recurring popularity in dieting guides, there is no scientific evidence supporting the idea that any food is calorically negative. While some chilled beverages are calorically negative, the effect is minimal[44] and drinking large amounts of water can be dangerous.
Cooking can prevent many foodborne illnesses that would otherwise occur if the food is eaten raw. When heat is used in the preparation of food, it can kill or inactivate harmful organisms, such as bacteria and viruses, as well as various parasites such as tapeworms and Toxoplasma gondii. Food poisoning and other illness from uncooked or poorly prepared food may be caused by bacteria such as pathogenic strains of Escherichia coli, Salmonella typhimurium and Campylobacter, viruses such as noroviruses, and protozoa such as Entamoeba histolytica. Bacteria, viruses and parasites may be introduced through salad, meat that is uncooked or done rare, and unboiled water.[19]
Adulteration is a legal term meaning that a food product fails to meet the legal standards. One form of adulteration is an addition of another substance to a food item in order to increase the quantity of the food item in raw form or prepared form, which may result in the loss of actual quality of food item. These substances may be either available food items or non-food items. Among meat and meat products some of the items used to adulterate are water or ice, carcasses, or carcasses of animals other than the animal meant to be consumed.[13]

Food is any substance[1] consumed to provide nutritional support for an organism. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth.