We don’t always eat what’s good for us — or good for the planet.

For years, researchers have extolled the health benefits of a plant-based diet, citing studies that show eating less meat lowers the risk of diabetes, heart disease and several other diseases.

And after the World Health Organization recently announced eating processed meat contributes to several kinds of cancers and red meat is a “probable” carcinogen, more Americans may want to consider the notion of a plant-based diet.

But that’s not the only reason: Our addiction to meat is hurting more than ourselves. Many scientists and organizations have become increasingly concerned about the impact of the typical American meat-based diet on the long-term health of the planet and our food supply.

In fact, for the first time in the country’s history, the panel of experts developing recommendations for the upcoming 2015 Dietary Guidelines for Americans — the country’s official nutritional advice — urged that the guidelines include the sustainability factor.

The bottom line: Eating more plants and less meat is better for the planet — that is, more sustainable. The advisory committee of 22 experts found the typical U.S. diet, with its dependence on meat, produces greater greenhouse gas emissions, which are implicated in climate change. This diet requires more water, energy and land than diets that are more plant-based. With this in mind, the expert panel urged the government to promote sustainably grown foods.

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The panel's recommendations were rejected, but you can take action by changing your own diet. Here are four reasons why a plant-based diet makes for a healthier planet.

1. It preserves natural resources. Meat production — especially beef — “takes vast amounts of water and agriculture devoted to producing feed corn and soybeans,” said Marion Nestle, a professor of nutrition and food studies at New York University, who supported the plant-based diet and sustainability recommendations. For example, it takes 1,850 gallons of water to produce a single pound of beef, compared to 39 gallons of water to produce a pound of most vegetables.

2. It cuts our carbon footprint. Studies show meat production produces significantly more greenhouse gases than vegetables. These gases include carbon dioxide, methane and nitrous oxide — the three main sources of greenhouse gas, according to Meatless Monday, a pro-plant nutrition organization. “The single most important consumer action to reduce greenhouse gases is to eat less beef,” Nestle said.

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3. It reduces the risks of antibiotic resistance. Our antibiotics don’t work as well as they did even 60 years ago, and scientists are concerned about being able to treat infectious diseases, according to the Centers for Disease Control and Prevention (CDC). Several deadly and increasingly untreatable bacteria have emerged. One reason: the widespread use of antibiotics in meat and poultry production. According to the CDC, when animals are given antibiotics for growth promotion or increased feed efficiency, bacteria are exposed to low doses of these drugs over a long period of time, which can lead to the survival and growth of resistant bacteria.

4. It helps assure a sustainable food base for the future. Plants feed more people for less, in terms of environmental, economic and health costs. The advisory committee for the Dietary Guidelines for Americans put it simply: “Access to sufficient, nutritious and safe food is an essential element of food security for the U.S. population. A sustainable diet ensures this access for both the current population and future generations.”

How so? According to the World Resources Institute (WRI), most of the world’s people consume more milk and meat than necessary, and many consume more than is healthy. Calories and protein from animal products is highly inefficient , according to the WRI. Even poultry, the most efficient source of meat, converts only around 11 percent of gross animal feed energy into human food. Changing the world’s menu to plants — or to just eating less meat — will help feed the world into the future, the WRI insists.

“Shifting toward plant foods and less carbon-intense animal foods is a great choice,” says Frances Moore Lappé, co-author of the best-selling “Diet for a Small Planet” and co-founder of the Small Planet Institute, an organization dedicated to reclaiming democracy through inclusion, fairness and mutual accountability in public life. “In one fell swoop, each of us can contribute to a sustainable food source, cut greenhouse gas emissions and benefit our own health."

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Judith Horstman (judithhorstman.com) is an award-winning journalist specializing in health and science. She has been a Washington correspondent, university professor and Fulbright scholar. She has also written for many publications, including Time Inc.,and is the author of seven books, including four Scientific American books about the brain.