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World Changing Ideas

A Vegan Diet Is Less Efficient For The Planet Than An Omnivorous One

To make best use of our land, it's probably best to eat fewer—but not zero—animals.

[Photo: Noah Clayton/Getty Images]

Ditching meat from our diets would save the planet, and save lives, or so the common thinking goes. The meat industry uses a huge amount of water (between 4,000 to 18,000 gallons to make a single burger), and produces tons of carbon. But switching to an all-vegan diet might not be the environmental rescue package we’d expect.

A new study, published in Elementa, looks at the consequences of switching the U.S. to different kinds of diet, from full vegan to various kinds of egg and cheese-supplemented vegetarian diets. And the results show that, while switching the country to vegan agriculture is indeed better than what we have now, the most efficient model is one that uses some animal products. A completely vegan food chain would actually feed fewer people.

The study looked at 10 different diets, and rated them on how efficiently they use available farm land. Calculations include the kinds of food that would be grown, the suitability of land for growing different kinds of crops, and the nutritional value of those foods, which translates to how much of a given diet is needed to feed everybody.

The diets come from three main groups: Current Consumption, Healthy Omnivorous, and Healthy Vegetarian. These are then split into further categories, with smaller and smaller percentages of meat (in the omnivorous category), and different kinds of animal products (dairy, eggs, none) in the vegetarian category. Also, an alternative "Positive Control" was derived from the Current Consumption diet, with the fats and sweeteners reduced to make it energy-balanced.

The result is a range of diets, from 100% vegan to 100% healthy omnivore. Which is best?

In terms of "carrying capacity," or efficient use of land, the lacto-vegetarian diet can feed the most people, and you still get to enjoy delicious cheese. A fully vegan diet, with no animal products at all, is less efficient than one which has some meat.

The diet that makes the least efficient land use of all? The baseline diet: the diet that most of the U.S. eats today.

So why isn’t vegan the most efficient of all? Because some kinds of land just aren’t suitable for crops, but they can sustain grazing. If you stop raising animals on these lands, then that land goes to waste.

Of course, this is all hypothetical. Your Uncle Pete isn’t going to give up his All-American bloody steaks, or eat Tofurkey for Thanksgiving. But this study might prove essential for future planning, because it quantifies not only how well different diets can feed a population, but what the impact of those diets are on the land.

"We know that, in many ways, land use can have severe ecological impacts," lead author Christian Peters said in a press release. "For example, biodiversity loss; an extreme and inequitable competition for land, water, and energy; and carbon emissions, an adverse impact of converting corn to biofuels. Before we go about converting land to other uses, to develop sound agricultural policy, we have to understand the impact of dietary patterns on land use."

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