255 grams per week. That's the short answer to how much meat you can eat without harming the planet. And that only applies to poultry and pork.

Beef cannot be eaten in meaningful quantities without exceeding planetary boundaries, according to an article published by a group of DTU researchers in the journal Nature Food. So says Caroline H. Gebara, postdoc at DTU Sustain and lead author of the study."

Our calculations show that even moderate amounts of red meat in one's diet are incompatible with what the planet can regenerate of resources based on the environmental factors we looked at in the study. However, there are many other diets—including ones with meat—that are both healthy and sustainable," she says.