Diet plays an important role in the genesis of obesity. Personal choices, advertising, social customs and cultural influences, as well as food availability and pricing all play a role in determining what and how much we eat.

Dietary energy supply

Average per capita energy consumption of the world from 1961 to 2002

The dietary energy supply is the food available for human consumption, usually expressed in kilocalories per person per day. It gives an overestimate of the total amount of food consumed as it reflects both food consumed and food wasted. The per capita dietary energy supply varies markedly between different regions and countries. It has also changed significantly over time. From the early 1970s to the late 1990s, the average calories available per person per day (the amount of food bought) has increased in all part of the world except Eastern Europe and parts of Africa. The United States had the highest availability with 3654 calories per person in 1996. This increased further in 2002 to 3770. During the late 1990s, Europeans had 3394 calories per person, in the developing areas of Asia there were 2648 calories per person, and in sub-Sahara Africa people had 2176 calories per person.