John Cisna now works as a brand ambassador for McDonald's after his experiment grabbed headlines nationwide, according to a company spokeswoman. Cisna said he lost nearly 60 pounds in six months during his diet that he started as an experiment for his science class.
"Today, John serves as an official brand ambassador for McDonald’s and travels the country sharing his story about the importance of choice and balance," a McDonald's spokeswoman said in a statement to ABC News, noting that Cisna is not a McDonald's employee but is paid for his appearances.
Cisna told ABC News that he was able to lose weight and get healthy during the six months by walking 45 minutes every day and eating healthy options on the menu. Cisna, with the help of his students, said he watched his calories so that he stayed at 2,000 calories per day to lose weight and followed the nutrition guidelines set by the U.S. Food and Drug Administration.
Cisna said at the beginning of the experiment he was 280 pounds or "one step from the sumo wrestling team."
"This is what is astounding, after 90 days I lost 37 pounds, my cholesterol went from 249 to 170," Cisna told ABC's Columbia, South Carolina, affiliate WOLO-TV.
He said he ate about 100 items on the menu in various combinations during his experiment and never got sick of the food. The experiment was sponsored by a local McDonald's operator, but no one at the company headquarters were initially aware of the experiment, he said. Three months into the experiment, Cisna said he wasn't surprised to have lost the weight due to calorie restriction, but said he was astounded when other tests came back positive.
"It really got exciting for us halfway through and when I got the blood work back I thought there was a mistake with the lab," he told ABC News today. "The blood results were so good ... I thought 'Oh my god, we're onto something.'"
Cisna, who is still employed as a substitute teacher, said he's happy he gets to share his story as brand ambassador. He said he doesn't want people to eat an all-fast food diet, he just wants people to realize they can find healthy options that even at fast food restaurants.
"You can eat any food that you want to -- but it's calories in and calories out," he said. "Enjoy the food like they were meant to be."
Public health expert Stephanie Morain, a fellow at the Johns Hopkins Berman Institute of Bioethics, said Cisna's story can be used to help people consider healthier options at fast food restaurants, but that doesn't mean his experiment will work for everyone as a weight loss plan.
Morain pointed out that Cisna could afford McDonald's healthier options, such as its salads, which are a little more expensive than its burgers. She said he was also likely aided by his own ability to break down caloric and nutritional information, and he was further motivated by the support of his students.
Still, in areas where people have little access to fresh foods that are affordable, Morain said having fast-food restaurants that push healthier options could have a positive impact on daily customers.