Center for American Progress

It’s Easy Being Green: What’s a Climate Friendly Diet?

It’s Easy Being Green: What’s a Climate Friendly Diet?

Authors and researchers examine the effects of diets on the health of humans and the planet, and they find altering habits can improve the health of both.

Recent research has pointed out the many benefits of a reduced-meat diet. One study found that a plant-based diet uses roughly one-fourth as much energy as a diet rich in red meat. (AP/Larry Crowe)
Recent research has pointed out the many benefits of a reduced-meat diet. One study found that a plant-based diet uses roughly one-fourth as much energy as a diet rich in red meat. (AP/Larry Crowe)

Read more articles from the "It’s Easy Being Green" series

“Much about the typical American diet is wrong,” said New York Times food columnist Mark Bittman, author of Food Matters: A Guide to Conscious Eating, in an interview with National Public Radio. “It’s damaging both individually and globally, and we can’t expect Big Food or the government to help us fix it.”

Bittman and fellow food writer Michael Pollan—who coined the mantra “Eat food. Not too much. Mostly plants.”—may be on to something. With the United States accounting for about 28 percent of the world’s total greenhouse gas emissions, and agriculture contributing to around 18 or 19 percent of that total, it’s worth taking a closer look at U.S. food production and consumption, not only for the planet’s sake, but our own as well.

Industrial farming is resource intensive and has many environmental side effects. Methane emissions from factory farms contribute to global warming and degrade local air quality, and poor waste management practices pollute local water supplies with little consequence. Americans raise and slaughter 10 billion animals each year for consumption, according to the Humane Society of the United States. Many of those animals are fed diets consisting mainly of corn, which also must be grown on arable land. Corn requires large amounts of fertilizer and pesticides, both of which require lots of fossil fuels to manufacture. And eating corn increases cattle’s methane emissions from flatulence since these animals didn’t evolve to subsist on it.

Recent research has also pointed out the many benefits of a reduced-meat diet. Decreasing our meat consumption by 10 percent, Bittman writes, “would have both an environmental impact and an impact on all of our mutual health.”

He’s not the only one who has concluded that less meat is good for the planet and our health. A 2006 study by Gidon Eishel and Pamela Martin, assistant professors of geophysics at the University of Chicago, found that a vegetarian diet is more energy efficient than one containing meat.

The authors collected data from a wide range of sources, examining the amount of fossil fuel energy required to sustain five different diets. The vegetarian diet turned out to be the most energy efficient, followed by a poultry-based diet and what the authors called the “mean American diet,” which consists of a bit of everything. Diets high in fish and red meat ended in a “virtual tie” for last place based on energy required. When the authors took into account other factors, such as bovine flatulence and methane gas from manure, red meat came out the bigger loser.

The authors compared a Toyota Prius, which uses about one fourth as much as fuel as a Chevrolet Suburban SUV, to a plant-based diet, which uses roughly one-fourth as much energy as a diet rich in red meat. Shifting from a diet rich in red meat to a diet based more on plants cuts greenhouse gas emissions as much as shifting from a Suburban SUV to a Prius.

The American diet follows a trend seen in industrial, high-income societies. When incomes rise, people tend to consume more animal protein as beef, pork, poultry, eggs, and seafood, according to the Earth Policy Institute, a non-profit environmental research organization. This universal inclination not only increases indirect grain consumption per person in the form of livestock and poultry feed (the United States uses 800 kilograms annually) but may also affect life expectancy.

The United States—where many people live high on the food chain—compares poorly to many countries in terms of life expectancy. Italy, for example, has a higher life expectancy, even though U.S. medical expenditures per person are much higher. A number of recent studies have shown the health benefits of a Mediterranean diet, which is typical for Italians (and Greeks). Whole grains, vegetables, nuts, and seeds, along with olive oil, provide the main source of fat in this diet, while meat, cheese, and seafood, and other foods high in saturated fat that form a larger chunk of the American diet, are enjoyed in moderation. India, a low-income country, faces the opposite problem: The average person does not consume enough protein, and eating more protein-rich foods can improve health and life expectancy.

The Earth Policy Institute suggests that by moving down the food chain, Americans can lead healthier lives and help reduce the demand for land, water, and fertilizer to produce grain and animal products, cutting emissions in the process.

So what about those of us who don’t want to go entirely vegetarian, but want to eat healthier and reduce emissions? Not everyone will want to switch to a completely plant-based diet, so Bittman recommends small changes: eat less meat, and fewer animal products in general; eat fewer refined carbohydrates, such as white bread, cookies, white rice, and pretzels; and eat far more vegetables, legumes, fruits, and whole grains. Pollan advises that, “A little meat won’t kill you, though it’s better approached as a side dish than a main.”

Bittman saw results from following such a diet in several health measures. He lost weight, and his cholesterol and blood sugar improved significantly. His idea behind writing the book was to help others see similar results, along with the realization that enough people eating the same way could have an impact on climate change (he included 75 recipes in the book to help people get started).

“This way of eating is far from complicated, has few rules, makes sense, and works,” Bittman said in the book. “It can have its own reward in better health and often weight loss, but it also is a way to save energy in the same way as carpooling, turning off the lights when you’re not in the room, lowering the thermostat during the winter and wearing a sweater in the house, installing a windmill, whatever other parallel you care to draw.”

Read more articles from the "It’s Easy Being Green" series

The positions of American Progress, and our policy experts, are independent, and the findings and conclusions presented are those of American Progress alone. A full list of supporters is available here. American Progress would like to acknowledge the many generous supporters who make our work possible.