"I'll be honest with you, it hurts me more than it hurts her," the 57-year-old R&B singer tells "Access Hollywood" in an interview that was to air Monday. "I must tell you, I'm the basket case."
Richie, 24, co-stars with ex-friend Paris Hilton in the E! reality-style series "The Simple Life — 'til Death Do Us Part." A new format allows the feuding friends to have nothing to do with each other.
In a recent interview in Vanity Fair magazine, Richie acknowledged she was "too thin right now" and was getting treatment to add pounds.
Richie says he has talked to his daughter about her weight.
"Of course, I mean, what are fathers for if you can't point the finger every once in awhile," he tells "Access Hollywood."
"I think the good part of it is she is aware of it. ... She has heard this all of her life from me, so this just a continuation of the reminder."
His new album, "Coming Home," is slated for release Sept. 12.
E! Entertainment Television announced earlier this month that it will air a fifth season of "The Simple Life," which shows the tabloid-ready celebutantes thrown into everyday situations with real people.