11/04/2013 AT 02:00 PM EST
Hollywood diets can be extreme, but this one tops them all.
admitted to The Telegraph
she used to be part of a cult that believed humans could live without food or water, with only sunlight for nourishment, a way of life called breatharianism.
"They believed that people in their highest state were breatharian," she said, explaining that she was put on a diet "nobody can adhere to."
Pfeiffer realized that the group was trying to manipulate her when she and her first husband, actor Peter Horton, conducted research on the Moonies, which was officially called Rev. Sun Myung Moon's Unification Church. Pfeiffer and Horton interviewed one of the members about the experience of being in a cult, adding it was then she realized, "I was in one."
"We were talking with an ex-Moonie and he was describing the psychological manipulation and I just clicked," she said.
Pfeiffer, who is still a strict vegan, left home for Los Angeles when she was 20 and met a "very controlling" couple as she was just starting out in Hollywood.
"They worked with weights and put people on diets. Their thing was vegetarianism," she said. "They were very controlling. I wasn't living with them, but I was there a lot and they were always telling me I needed to come more. I had to pay for all the time I was there, so it was financially very draining."