ABC said the interview is to air on the network Friday.
"'One day at a time' has taken on a new meaning for Valerie Bertinelli," ABC said in a news release Thursday. "Everyone got a fresh look at her recently when the former sit-com star shed weight and posed in a bikini. Now, as she struggles to keep off the weight, Bertinelli speaks candidly to ABC News Contributing Correspondent Chris Connelly about her new perspective on her body, motherhood and raising a teen rock star, her broken marriage to rocker Eddie Van Halen, and former co-star Mackenzie Phillips."
Phillips, who played Bertinelli's big sister on the TV series "One Day at a Time," revealed last month in her own memoir that she had a long-running sexual relationship with her father, the late Mamas and the Papas musician, John Phillips.
Notable deaths of 2014 [PHOTOS]