If you’ve switched from meat to dairy to get your protein, in the name of eating healthy, you’re still not looking at climate change. According to a new report in the Journal of Industrial Ecology, eating less meat and more vegetables won’t help greenhouse gas emissions if you’re still slicing into that cheese block.
University of Michigan researchers Martin C. Heller and Gregory A. Keoleian’s have crunched the numbers on the USDA’s recommended diet to calculate how the diet adds up when looking at greenhouse gas emissions. To do this Heller and Keoleian analyzed 100 foods for their associated amount of food waste and then calculated each food group’s average greenhouse gas emissions.
The USDA diet suggests you eat plenty of fruits and vegetables, whole grains, seafood, one to three servings of low-fat dairy products, and although it’s not explicitly stated, less meat and a recommended 2,000-calorie intake. So, they asked, how would emissions change if Americans followed the USDA diet that contains a target 2,000-calories, or, America’s current over-consumption average of 2,534?
Surprisingly, when comparing a USDA recommended diet of 2,534 versus 2,000 calories, Heller and Keoleian found shifting calorie consumption down to 2,000 calories only decreased greenhouse gas emissions by 1 percent. Moreover, shifting to the healthier, recommended USDA diet, while still eating 2,534 calories, would actually increase emissions by 12 percent overall. Their reasoning? Dairy. Decreasing calories by 20 percent is one thing, but “decreased quantities of meat, poultry, and eggs and an increased need for dairy in the diet,” is another, and it plays a large role in why the drop in emissions is not higher.
“There is a balance in that trade off that results in roughly the same level of GHG emissions,” said Heller. “ For all practical purposes, we should expect that that the environmental impact associated with our diet would decrease when we decrease caloric intake in general. But obviously the point is that study is it depends on what you eat.”
Heller and Keoleian agree that beef still represents a huge portion of GHG emissions, accounting for nearly 36 percent of global emissions while only being 4 percent by weight of the retail-level food supply. In analyzing food waste, Heller and Keoleian report that beef alone represented the “single largest contributor from wasted food, even though the quantity of beef wasted was less than 2 percent of total waste by weight.”
Not surprisingly, lacto-ovo vegetarians, vegetarian and vegan diets all fared well in producing fewer emissions than their meat-filled diets. Heller, however, cites Harvard’s Healthy Eating Plate as an alternative to the USDA’s “My Plate” where they propose eating less dairy, as an alternative.
“There’s a controversy over what an ideal or recommended diet should look like,” Heller said. “We analyzed [Harvard’s Healthy Eating Plate] and saw that it has greenhouse gas emissions that are roughly the same as the vegetarian dietary patterns provided by the dietary guidelines for Americans.”
As for what would really curb emissions? Heller says the amount of food waste in the U.S. is “roughly equivalent in greenhouse gas emissions to the savings the U.S. would realize, as a country, going to a completely vegetarian diet.” A scenario he says is not really likely.
The findings overall emphasize that in creating recommended “food patterns” we should also think about the environmental costs. They conclude that, “Increasing the efficiency of our food system by reducing food waste and improving diets is an important strategy for U.S. climate-change mitigation and requires collaborative efforts by businesses, governments, and consumers.”