It doesn't take a transcontinental flight to end up out of sync with your body clock. It might just be that you stay up too late. iStockphoto.com hide caption

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The FDA hasn't approved a new weight-loss drug since 1999. In the meantime, Americans' waistlines have continued to grow. M. Spencer Green/AP hide caption

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Jenny Craig brand ambassador and singer Mariah Carey (left) poses with Dana Fiser, CEO of Jenny Craig, at a press conference in New York City in November. Cindy Ord/Getty Images hide caption

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Hoodia gordonii plants like this one have been used by generations of bushmen in Southern Africa's Kalahari desert as an appetite suppressant. But the Federal Trade Commission isn't sold on that idea. David Silverman/Getty Images hide caption

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One recent study found that people were able to burn up an extra 450 calories a day with one hour of moderate exercise. That can include walking briskly, biking or swimming.

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