Vegetarian and 'healthy' diets are more harmful to the environment

December 14, 2015
Credit: Maliz Ong

Contrary to recent headlines—and a talk by actor Arnold Schwarzenegger at the United Nations Paris Climate Change Conference—eating a vegetarian diet could contribute to climate change.

In fact, according to new research from Carnegie Mellon University, following the USDA recommendations to consume more fruits, vegetables, dairy and seafood is more harmful to the environment because those foods have relatively high resource uses and greenhouse gas (GHG) per calorie. Published in Environment Systems and Decisions, the study measured the changes in energy use, blue water footprint and GHG emissions associated with U.S. food consumption patterns.

"Eating lettuce is over three times worse in than eating bacon," said Paul Fischbeck, professor of social and decisions sciences and engineering and public policy. "Lots of common vegetables require more resources per calorie than you would think. Eggplant, celery and cucumbers look particularly bad when compared to pork or chicken."

Fischbeck, Michelle Tom, a Ph.D. student in civil and , and Chris Hendrickson, the Hamerschlag University Professor of Civil and Environmental Engineering, studied the to determine how the obesity epidemic in the U.S. is affecting the environment. Specifically, they examined how growing, processing and transporting food, food sales and service, and household storage and use take a toll on resources in the form of energy use, water use and GHG emissions.

On one hand, the results showed that getting our weight under control and eating fewer calories, has a positive effect on the environment and reduces energy use, water use and GHG emissions from the supply chain by approximately 9 percent.

However, eating the recommended "healthier" foods—a mix of fruits, vegetables, dairy and seafood—increased the environmental impact in all three categories: Energy use went up by 38 percent, water use by 10 percent and GHG emissions by 6 percent.

"There's a complex relationship between diet and the environment," Tom said. "What is good for us health-wise isn't always what's best for the . That's important for public officials to know and for them to be cognizant of these tradeoffs as they develop or continue to develop dietary guidelines in the future."

CMU's Steinbrenner Institute for Environmental Education and Research and the Colcom Foundation funded this research.

Explore further: Meat food waste has greater negative environmental impact than vegetable waste

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5 / 5 (4) Dec 15, 2015
"...because those foods have relatively high resource uses and greenhouse gas (GHG) emissions per calorie..."

"per calorie"? That is obviously stupidly biased because given that we don't only require calories in our diet but also water, roughage and various other nutrients other than calorific ones, why make the measure the environmental impact obviously biased against veterinarian diets by measuring the environmental impact calorie and not per, say, volume or per mass?

"Eating lettuce is over three times worse in greenhouse gas emissions than eating bacon,"

well Dirr -is that per calorie or per volume? If per calorie, lettuce has very few calories and thus isn't eaten for its high calorific content. I am sure that, per volume, it has vastly less environmental impact than bacon!

Was this stupidly obviously biased attack against vegetarianism funded by the meat industry?
5 / 5 (2) Dec 15, 2015
I am not sure how this researcher got to these numbers. Fruits and Vegetables are plants which means that they absorb carbon as they grow. Animals excrete methane as they grow. Since both plant and animal foods usually are transported. It seems unrealistic that plants would cause more green house gases. The researcher must have assumed that the chicken was raised in someones back yard and the egg plant was raised in Brazil and transported by itself to the U.S. in a chartered Lear Jet and delivered by courier. This sort of nonsense should never see the light of day. Now Vegans will be getting grief for months from Paleo and low carb devotes claiming it has been proven beyond any doubt that Lettice causes climate change and bacon does not.
5 / 5 (2) Dec 15, 2015
I guess it's good that "The Onion" is finally getting some competition. But I did like the old Physorg site. Too bad they've made this editorial change to satirical humor. Does anyone out there have an actual reputable science news site that I can switch to?
5 / 5 (2) Dec 15, 2015
This is a pile of opinion not a paper, trash bin.
Per calorie more for lettuce is really over the top in searching for a place other than a toilet to publish this ... what a crock, from the title on down to the appalling bias shown.
5 / 5 (1) Dec 16, 2015
Good to see the above commentators have all looked into the figures and data to provide us with such interesting and factual views.

Great counter arguments guys - are you sure you should be reading this website?
5 / 5 (2) Dec 16, 2015
However, eating the recommended "healthier" foods—a mix of fruits, vegetables, dairy and seafood—increased the environmental impact in all three categories: Energy use went up by 38 percent, water use by 10 percent and GHG emissions by 6 percent.

I'm not sure what they're saying here. Did these numbers go up per calorie? Or total? It makes sense that the total numbers would go up if more of a certain food were consumed.
However, one should make sure to counterbalance the decrease in other foods (i.e. less meat consumed) at the same time.

While meat is more energetically dense there is a quite low conversion factor from feedstock to 'bacon'. If we posit that a drop in meat consumption will also reduce the amount of feedstock needed (and that that feedstock could be replaced with fruits/vegetables) I'm pretty sure that the balance would come out positive for a healthier diet. (This is entirely besides any CO2/methane issue that is not in favor of meat)

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