According to the Food and Agricultural Organization, “On average, a person needs about 1800 kcal per day as a minimum energy intake.” (A kcal – kilocalorie – is a measure of food energy, also known as the Calorie). For comparison, the US government recommends 2,500 per day, on average (a recommendation that is certainly exceeded by most people, but I digress).
The unit of kcal/person/day provides a useful basis for evaluating total food supply as compared to population. The graph at the top of this post shows such an evaluation, based on data downloaded from FAOSTAT (thanks RTC!).
The data show that from 1961 to 2007, when the dataset begins and ends, global food supply in kcal/person/day has steadily and consistently increased such that it has been for many decades comfortably above the level deemed necessary to meet individual nutritional needs.
In fact, if food supply distribution were perfectly efficient (which of course it is not) the world could feed an additional 1-3 billion people with the food produced in 2007 (depending on your view of nutritional requirements). This can be hard to reconcile with the fact that in 2007 the UN found about 1 billion people globally to be “undernourished.” So there is considerable “headroom” for progress even without increasing global food supply, and UN data show progress in recent years.