Katie, nicknamed "the wicked witch" in the U.K., documented her weight experiment in a TV special called My Fat Story, and she spoke to ET's Brooke Anderson about the event.
"I do think overweight people are lazy," Katie told Brooke. "The hardest thing to do is stand in front of the mirror and say you have got the problem you caused the problem, there's no excuses, and you're the only person who can do something about it."
The 39-year-old mother of three runs a small business consultancy firm, but according to her, plus-sized hopefuls need not apply.
"I would never hire an overweight person," Katie told ET. "My business is all about directing energy into businesses, helping them make more money. For me a very fat person -- a very obese person, an overweight person, whatever name we call that -- would not represent my company in the way I think is important. They certainly wouldn't be able to fly around the city at the speed I fly around the city. And what I don't want is the lasting image of my company to be 'Did you see the size of that person?'"
In her experiment, she went from 125 pounds to 167 pounds in three months by eating and lying around the house. She kept a video diary and even let the cameras roll when she hit a wall.
"I hate fat people for making me do this," she said at one point in the special.
Katie successfully took the weight off again by cutting back to 1,500 calories a day and going through rigorous exercise. The campaign certainly didn't do much for her popularity, but she stuck to her guns.
"I think I'm right to be bruising my way along on this issue, because so many people are willing to tiptoe around it," Katie said.