Off the wagon

If Oprah Winfrey ever writes her own diet book, it will have a lot of chapters.

Winfrey has been in the news for her yo-yo weight as often as her accomplishments, and the next headline will come in January's O magazine: She confesses that she's "fallen off the wagon" of healthy living and is seeing the dreaded number 200 on her scale.

Winfrey says she's gained 40 pounds since 2006, partly due to a "fear of working out" after battling an out-of-balance thyroid.

"I look at my thinner self and think, 'How did I let this happen again?' " she says in the magazine.

"I'm embarrassed," Winfrey, 54, says. "I'm mad at myself."

Winfrey's weight and height put …