Many individuals limit what foods they eat for reasons of morality, or other habit. For instance, vegetarians choose to forgo food from animal sources to varying degrees.

Others choose a healthier diet, avoiding sugars or animal fats and increasing consumption of dietary fiber and antioxidants. The listing of items included as foodstuffs include any substance intended to be, or reasonably expected to be, ingested by humans.

Between the extremes of optimal health and death from starvation or malnutrition, there is an array of disease states that can be caused or alleviated by changes in diet.

Deficiencies, excesses, and imbalances in diet can produce negative impacts on health, which may lead to various health problems such as scurvy, obesity.

Some countries list a legal definition of food. These countries list food as any item that is to be processed, partially processed, or unprocessed for consumption.