While McDonald’s has recently pledged to incorporate sustainable meat into its menus, the company admits that it doesn’t know exactly what that will mean. Sustainable food means different things to different people. But does it mean delicious? And can it be affordable? Monica Eng and Louisa Chu tackle this week on their WBEZ food podcast Chewing the Fat. They preview the episode with a break down of what chefs mean when they say they are serving sustainable food. To illustrate their points, Tony samples a “sustainable” and “unsustainable” burger. Photo: Flickr/Alaina Browne