A big man has sued White Castle hamburgers in New York because the booth was too small for him and he limped out of the restaurant.  The lawsuit claims he smacked his knee into a metal post on one visit in 2009.  He filed suit under the Americans with Disabilities Act.  See MSNBC story.  "I’m not humongous, but I am a big guy," said the stockbroker.  The 290 pound man says he has no such problems at other fast-food establishments.  He loves White Castle burgers.  Even after the 2009 visit, he asks his wife to purchase the burgers for him.  

Title II of the ADA does require public facilities to accommodate persons with disabilities.  Being overweight is not a disability, but a diagnosis that leads to being overweight might constitute a disability.