(CNN) -- Up to half of the world's food is wasted, according to a new report that found production inefficiencies in developing countries and market and consumer waste in more advanced societies.
The British-based independent Institution of Mechanical Engineers said about 4.4 billion tons of food is produced annually and roughly half of it is never eaten.
Some of it is lost to inefficient harvesting, storage and transportation, while the rest is wasted by markets or consumers. The group also said food waste also impacts land, energy and water use.
"This level of wastage is a tragedy that cannot continue if we are to succeed in the challenge of sustainably meeting our future food demands," the group said in its report.
Starting the study in 2010, engineers began examining populations that were fully developed, such as those in Europe.
They also analyzed food production and consumption practices in countries at various states of development, like China, and newer levels of development, like those in Africa.
While waste occurred globally, broader food production problems seem to be more prevalent in less developed areas.
In sub-Saharan Africa, waste typically occurrs at the farmer-producer end of the supply chain, the study showed. Harvesting, transportation and infrastructure also tend to be poor. And food is also rarely stored properly in these areas.
In Southeast Asia, up to 80 percent of the rice harvest is lost, the group noted.
As far as the developed world, Britain has much more efficient farming practices, better transportation, storage and processing facilities. But food is still wasted at the wholesale and retail levels.
Customers end up throwing away as much as half of what they buy, the study said.
Markets also waste food.
"Major supermarkets, in meeting consumer expectations, will often reject entire crops of perfectly edible fruit and vegetables at the farm because they do not meet exacting marketing standards for their physical characteristics, such as size and appearance," the study said.
Because of that, up to 30% of Britain's vegetable crop is never harvested.
Moreover, sales promotions "frequently encourage customers to purchase excessive quantities," which they don't eat, the study said.