A growing global middle class, when they have more money to spend on food, wants meat, study author Deepak Ray with the Institute on the Environment at the University of Minnesota told NBC News.
"In Africa, if you become prosperous, what are you going to go and eat first? You are going to change from eating cassava," a root vegetable "which everybody hates, to having chicken or beef," he said.
"That is going to happen. There is no way around it in spite of all of our efforts."
Crop yields are improving too slowly to satisfy meat-eaters' appetites, the researchers said, suggesting global crop production must double by 2050 to meet predicted demands from increasing population, diet trends toward more meat and dairy products and increasing biofuel consumption.
Currently, they said, yields of four key crops -- corn, rice, wheat and soybean -- are increasing at rates between 0.9 and 1.6 percent a year, well below the needed 2.4 percent increase needed to double crop production by mid-century.
"Alternatively, additional strategies, particularly changing to more plant-based diets and reducing food waste can reduce the large expected demand growth in food," the researcher said in reporting their study in the journal PLoS ONE.