Food is the name given to substances ingested (eaten) by living creatures for the purpose of obtaining energy and nutrients and so sustaining life. All living organisms must eat in order to survive.
For many living things, eating is simply a survival measure. Human beings, however, have evolved to where eating food is not simply done to maintain their lives, but a social activity. The preparation, presentation, taste and smell of food constitutes a dining experience.
See the full article at Food Science
Food deprivation: hunger and starvation
The lack of food leads to malnutrition, which is evidenced by illness and disorder, and ultimately to death by hunger, which is called starvation.