In his initial analysis of his six challengers, Bob laid down the law on Barbara's 30-year-old pack-a-day smoking habit. He promised a zero-tolerance policy—one drag and she's out!

Bob says if you make a commitment to losing weight but keep on puffing, you're just setting yourself up for future failure when you do kick the butts. "You … lose weight and need to quit later, at which time you'll gain that weight back. So quit now," he says. "It's the most important thing you can do for your health."

Barbara says she made the commitment to quit right on the set of The Oprah Winfrey Show…but Bob wanted to be sure.

Did she really quit? Watch Bob's surprise visit to Barbara's house.

Just to be absolutely sure that she's quit, Dr. Gulati ran a special test on Barbara to see if she had any nicotine in her system…and Barbara passed. "I told you," Barbara says. "Can I do a happy dance?"

"Not only did she quit smoking, she said [she was] addicted to food," Bob says. "She gave up two vices and lost weight. Very unusual. It's great."