Emily Gershwin: We are living in a country where, again, most people's BMIs put them in the overweight or obese categories. And yet still, the designs that we are making for physical spaces are sort of centered around a minority of people. She says one of the biggest ally things that people can do for her is to tell thin friends they can't sit at their favorite table. "It doesn't call any attention to itself and it makes all the difference in the world"