The study also addresses impacts on the environment and climate.
But the study said eating meat in small amounts can be quite sustainable. The results are published in the journal Annual Review of Resource Economics.
Livestock farming damages the climate and the environment., the study said.
For example, ruminants produce methane which accelerates global warming. Animals also convert only a portion of the calories they are fed into meat.
In order to feed the same number of people, meat therefore requires a much larger land area. This is to the detriment of ecosystems, as less space is left for natural species conservation. Furthermore, those eating too much meat live risky – meat in excess is not healthy and can promote chronic diseases, said the study led by Prof. Matin Qaim of the Center for Development Research at the University of Bonn.
"If all humans consumed as much meat as Europeans or North Americans, we would certainly miss the international climate targets and many ecosystems would collapse," he said.
"We therefore need to significantly reduce our meat consumption, ideally to 20 kilograms or less annually.
"The war in Ukraine and the resulting shortages in international markets for cereal grains also underline that less grain should be fed to animals in order to support food security,” he said.
