If Americans change their diets to meet the current federal dietary guidelines, greenhouse gas emissions could increase, a new study reports.
University of Michigan researchers looked at the current USDA's dietary guidelines and the emissions associated with the production of 100 different foods. They then looked at how these emissions would increase or decrease if Americans adopted the dietary guidelines.
The current guidelines recommend Americans eat more fruits and vegetables, whole grains, fish, lean meat, and fat-free or low fat dairy products. It's well known that meat production is bad for the environment, and while the current guidelines do not say that Americans should decrease their intake, the recommended amount of consumption is lower than what Americans consume on average. A real drop in meat consumption would lower greenhouse gas emissions, but if that consumption is replaced with an increase in other animal-based foods, like dairy products, then emissions will once again go up.
The researchers point out animal-based foods are responsible for more greenhouse gas emissions per pound than plant-based foods, and that both beef and dairy cow production are tied to heavy emissions since they require a lot of feed (and therefore fertilizer and fuel for equipment.) Cows also excrete a significant amount of methane--even if they're just being milked.
The U.S. food system is paying more attention to sustainability, but the researchers say that our environmental and food goals are still not aligned. It's not like we do a great job of following these guidelines, anyway: the average American consumes about 2,534 calories a day, significantly more than the advised 2,000 calories. At 2,534 daily calories consumed, the researchers estimate an increase of 12% in greenhouse gas emissions. But even if we did obey the caloric guidelines and lowered our average intake to 2,000 calories, those emissions will only decrease by 1%. "This perhaps surprising result suggests that even with a greater than 20% decrease in caloric intake and considerable decreases in meat consumption, a shift to a recommended diet may not result in significant decreases in [greenhouse gas emissions]," the researchers write in their study.
The researchers call for more consideration for the environment when it comes to solving food-related issues like obesity and food waste. To be more sustainable, the researchers recommend Americans try to reduce the amount of animal products they eat on a regular basis.