Tufts Nutrition

If Americans change the way they eat, the existing U.S. farmland could feed a lot more people. In fact, a new model that measures the land needed to grow food for different diets suggests that a vegetarian diet with some dairy makes the most efficient use of the land we have—enough to feed 800 million people, or twice the number who could be fed with our current diet.

Nutritionally, our current diet isn’t something to brag about. It’s high in calories and sugar and low in fruits and vegetables and falls short of nutritional recommendations on many fronts. So Christian Peters, an associate professor at the Friedman School, and colleagues created a model that compared our current diet’s agricultural “foodprint” to that of nine other diets: one that mimicked our current diet but contained fewer calories, and eight “healthy” diets that comply with the Dietary Guidelines for Americans but varied in their mix of protein sources, such as meat, eggs, beans, nuts and tofu.

Our current diet had the lowest carrying capacity, meaning that it could feed the fewest people per acre, and required eight times more land than a vegan diet. The lower-cal version wasn’t far behind. But among the healthy diets, the vegan diet wasn’t the winner for land use: Some of the diets that included meat had higher carrying capacity than a diet completely free of animal products, in part because a vegan diet doesn’t make use of land that is only suitable for grazing. The diet that ranked highest was a vegetarian one that includes dairy products.

“Dietary choices can influence the ability of agriculture to meet our need for food,” Peters said. “Our approach challenges the 20th-century emphasis on increasing yield and production. Improving crop yields remains vitally important, but it is not the only way to increase the number of people fed per acre. Our aim is to identify potential agricultural sustainability strategies by addressing both food consumption and production.”

The research appeared in the journal Elementa.