In 1985, after many years in the fast-food business, Richard Thomas took a 180-degree turn and opened a health food restaurant, R. Thomas Deluxe Grill, on Peachtree Street in Atlanta. It struggled for 10 years, and then it became a local institution.

Mr. Thomas had owned multiple Kentucky Fried Chicken and Pizza Hut units, and he had helped found the Bojangles’ Famous Chicken ’n Biscuits chain, which he built into 28 locations across Michigan, Indiana, Ohio, and North and South Carolina and sold for $12 million in 1982.

He got the idea to open a health food restaurant after traveling around California, where he sampled the menus of the kinds of places that were not easily found in the South in the 1980s. Later, he was further motivated when he met a nutritional consultant, Donna Gates, author of “The Body Ecology Diet,” who told him that he had been poisoning people with his fried food.

Mr. Thomas opened his grill in 1985 with 48 seats, investing $528,000, then waiting patiently for Atlanta residents to expand their palates beyond fatty, hyperprocessed food. He turned a small profit five years out but really started to make money only in 1995. Today, the place has 94 seats, employs 42, is swamped on weekends — especially from 8 p.m. to 4 a.m. — and generates $4 million a year in revenue.