Only 55% of food-crop calories are consumed directly by humans. The rest: fuel and feed.

Crops grown for food (green) versus for animal feed and fuel (purple) . Image: National Geographic.

Crops grown for people to eat (green) versus for biofuel, or for animals to eat (purple). Image: National Geographic.

In this National Geographic feature on the future of food, a map that illustrates how much of the world's crops are grown for people to eat directly (green), compared to crops grown for biofuel or to feed animals.

"Only 55 percent of food-crop calories directly nourish people. Meat, dairy, and eggs from animals raised on feed supply another 4 percent."

As advocates of plant-based diets have long argued, we could feed more humans by shifting our diets away from animal products, which consume more land, more fuel, and produce more emissions and pollution that adversely affect climate and environment.