As the media mogul, 54, writes in the January issue of her O magazine hitting newsstands Tuesday (and provided in advance to the Associated Press by Winfrey's Harpo Productions): "I'm embarrassed … I can't believe that after all these years, all the things I know how to do, I'm still talking about my weight. I look at my thinner self and think, 'How did I let this happen again?' "
For starters, the fact that her thyroid was out-of-balance gave her "a fear of working out," she says. "I was so frustrated I started eating whatever I wanted – and that's never good."
Having slimmed down to 160 in 2006, she admits, "Yes, you're adding correctly. That means the dreaded 2-0-0."
Past DietsWinfrey memorably revealed her new look on her show in 1988 – by wheeling out a wagon loaded with fat to represent the 67 pounds she had shed. On that episode, she sported a pair of size 10 Calvin Klein jeans.
"My greatest failure was in believing that the weight issue was just about the weight," Winfrey told PEOPLE in 1991. "It's about not handling stress properly."
But when it came to slipping into those jeans, "I had literally starved myself for four months [on a liquid-protein diet] – not a morsel of food," Winfrey, an admitted food addict, said in 2005. "Two hours after that show, I started eating to celebrate – of course, within two days those jeans no longer fit!"
Winfrey's weight has long been a topic on her show – and even for late-night hosts. In 1990, she hit 237 pounds, eventually prompting her in 1996 to enlist personal trainer Bob Greene. At the time, she said she had wanted to bring an end to her roller-coaster weight saga.
'Felt Like a Fat Cow'Choosing a gown for the Barack Obama inauguration coming up in January, however, made Winfrey realize her self-image was no longer jibed with the person standing on the scales – though the real low point occurred last April.
"I felt like a fat cow," Winfrey writes of the occasion when she sought to skip out on a Las Vegas show taping with Cher and Tina Turner. "I wanted to disappear."
According to the Centers for Disease Control and Prevention, Winfrey's weight and height rank her as obese, with a body mass index of 31.8 – putting her at "at higher risk for chronic conditions such as high blood pressure, diabetes and high cholesterol," says the CDC.
Winfrey intends to address the issue on The Oprah Winfrey Show, which will kick off Best Life Week Jan. 5.
She is also expected to discuss her weight that same day on her XM satellite radio station's The Gayle King Show. Winfrey will also host interactive live Web casts at Oprah.com the week of Jan. 12 to 16, nightly at 9 p.m. ET.
1991: Oprah says 'I'll never diet again!'
1996: Oprah gets buff with the help of a trainer!