The 47-year-old actress is enjoying a career rebound since she became a Jenny Craig spokeswoman and pledged to lose 30 pounds, which she has since revised to 40 pounds.
"It's so funny," Bertinelli said. "If you say you're fat, all of a sudden people like you! I've never had so many people be so kind and wonderful and giving and loving."
Viewers will see a heavier Bertinelli in her latest role, which she filmed before dropping more than 22 pounds. She plays a widowed psychic who helps catch a serial killer in the TV movie "Claire," airing Saturday on the Hallmark Channel.
Bertinelli was inspired by fellow Jenny Craig spokeswoman Kirstie Alley to go public with her weight battle.
"If Kirstie was able to do it so boldly, with such a great sense of humor, and be so successful at it, who am I to pretend that people don't see that I've gained all this weight?" she said.
"It took me a few days to prepare myself mentally. I thought, `Am I ready for this? It's so public. What if I fail?' Because of the response I've gotten from people, it's the best job I've ever had," she said.
Bertinelli starred in the 1970s sitcom "One Day at a Time." She was also a regular on "Touched by an Angel" from 2001 to 2003.
She married Eddie Van Halen in 1981, and filed for divorce from the rock guitarist in 2005.