This time around, Kirstie's proposing a six-month timeline to get herself in shape. "By November, I have to look ripped," she says.

Oprah says she's learned over the years that setting a specific time limit on weight loss can hurt the end result. "I want you to do in in your own time," Oprah tells Kirstie. "Do it in a way that's going to be good for you. I don't want you on national television setting yourself up for November. ... I know what happens when you set that goal for yourself. Then you go home and eat for a month trying to make yourself feel better about what you just committed [to]."

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