Tilman and Clark caution that while the links between what makes healthy diet and what will help lower agricultural greenhouse gas emissions are clear, it’s also possible to eat “a pure junk food diet,”–think French fries, donuts, and tortilla chips–that has low GHG emissions.
So the solution to what the scientists call the “diet-environment-health trilemma” will require choosing menus high in plant-based, whole foods like those that fit in a Meditarreanean, “pescetarian” or vegetarian diet. If these diets become the norm by 2050, Tilman and Clark say “there would be no net increase in food production emissions.”
But they also note that making such a change won’t necessarily be easy. “The dietary choices that individuals make are influenced by culture, nutritional knowledge, price, availability, taste and convenience, all of which must be considered if the dietary transition that is taking place is to be counteracted,” write Tilman and Clark.
So, how do we counter the trend toward eating more meat and fatty food? “There are lots of policy options,” says Doug Boucher, director of climate research at the Union of Concerned Scientists. These include carbon taxes that would include agriculture as New Zealand now does, shifting agricultural subsidies away from livestock and related feed production, and changing government dietary guidelines to include sustainability and climate change considerations, as the U.S. Department of Agriculture’s (USDA) 2015 guidelines are expected to.
The USDA’s climate change program director, William Hohenstein, explains that rather than addressing the “trilemma” by focusing on the menu, the agency’s preferred strategy is to work with growers and livestock producers on practices that will reduce GHGs. “Consumers always have a choice,” says Hohestein.
If I understand the above article correctly, it is not demonizing healthy fats nor grass-fed beef. It is simply suggesting eating "less meat, less refined fat, and less sugar" than the average American diet results in better health, and more resilient ecosystems.
It is important to consider the sources of information. "Defending Beef" cites research, but it is opinion as well. The Nature article is more robust, comparing 50 years of data in 100 most populous countries. The DMII and cardiovascular disease rates in diets with less meat, sugar & fats are compelling.