It takes 24 pounds of grain to make 1 pound of beef.

This statistic, from Frances Moore Lappe’s 1971 book “Diet for a Small Planet,” is often cited in arguments for vegetarianism. Because animals eat more food than they produce, meat production also requires vastly more energy, land and water than plant-based food production. Statistics like this are slippery — I’ve read estimates of a cow’s lifetime petroleum use that range from 13.83 gallons to 284 gallons — but the argument stands: We could feed many more people with much less energy by eating plant food instead of feeding it to livestock.

Cows are usually considered the least sustainable form of meat because a cow’s body is least efficient at converting feed into body mass. This efficiency is known as a feed-conversion ratio. Industrially produced cows are fed mostly corn, mixed with fat and protein supplements, hormones and antibiotics.

Most of the energy, water and land required to make beef is embedded in that feed. The crops are treated with fertilizers made from fossil fuels, sprayed with industrially produced and toxic pesticides, heavily irrigated, and sown and harvested with gas-guzzling machines. Then they are transported from cropland in the Midwest to Concentrated Animal Feeding Operations (CAFOs) where the cows are raised, often more than 1,000 miles away. There, the corn is ground and chemicals are added before finally making its way into the massive feeding troughs.

But cows don’t have to eat petroleum-based corn laced with chemicals. They evolved to eat grass, and grass can easily grow without irrigation or pesticides. In a CAFO, manure is expensive pollution. On a pasture, it becomes the only fertilizer the grass needs. Suddenly, harvesting and transporting feed is a nonissue: Cows given grassy fields to graze happily are harvesting their own food.

Much of Central Texas is too hilly for farming, and our dry climate means vegetable production usually requires an unsustainable amount of water for irrigation, but we can easily grow grass on all of this land.

Additionally, including grass-based meats in our diets would allow us to source more of our food locally, reducing the carbon emissions from transportation. And because we can raise animals on land where vegetable production isn’t possible, “eating what the cows eat” is no longer an option. Feed conversion ratios aren’t relevant: Cows are turning grass — inedible to humans — into high-quality food.

What’s more, properly managed animal production is a great way to regenerate degraded land. Intensive crop production has eroded the soil and depleted the nutrients on most of America’s agricultural land. When cows are pastured on a large plot of land for a long period of time, their grazing pattern weakens the grass and contributes to the problem. However, a system known as management-intensive grazing actually increases soil ecology and builds topsoil. Virginia farmer Joel Salatin, who is featured in Michael Pollan’s book “The Omnivore’s Dilemma” and the documentary “Food, Inc.,” popularized this system which involves enclosing the cows in small sections of the pasture for short periods of time, then giving the grass time to grow back before allowing them to graze the same area again.

Killing an animal is a serious decision and one that most probably don’t give much thought. Vegetarianism is a reasonable response to the reality of today’s beef-production industry. Additionally, we don’t have enough land to continue to support the average American’s level of meat consumption. Grass-based meat production requires more land per animal than crop-based meat production, so even though we can do it on marginal land, it can’t produce enough meat for us to eat at every meal.

In terms of environmental impact, a diet based on industrially produced vegetables is less damaging than one based on industrially produced meat. But a truly sustainable food system is about more than just doing the least damage. Rather than calculating which currently available option uses less fossil fuel and causes less environmental damage, we need to create a new system of agriculture that actually reverses the current system’s environmental damage. And in Texas, that system will probably have to include meat.