Government guidelines say exercising 2.5 hours a week will keep you healthy, but a study says you can get the job done in less time if you rev it up. iStockphoto hide caption

Woman weighing herself. ImageZoo/Corbis hide caption

Electrical impulses generated by a pacemaker-like device are transmitted to the vagus nerve by electrodes. Enteromedics hide caption

Sure, these Buffalo-chicken-and-kale-stuffed mushrooms look tasty, but they aren't the giant bowl of salt and corn syrup your brain really, really wants. Matthew Mead/AP hide caption

Belviq, a weight-loss drug from Arena Pharmaceuticals, was approved by the Food and Drug Administration in 2012. With the agency's approval of Saxenda in December, there are four new weight-loss pills available. Arena Pharmaceuticals Inc/Reuters/Landov hide caption

If losing weight has you feeling light as air, you may be on to something. Terry Vine/Corbis hide caption

Wouldn't it be great if this stuff really did cause quick painless weight loss? iStockphoto hide caption

Even versions of Zi Xiu Tang Bee Pollen labeled "genuine" and "anti-counterfeit" have been found to contain the drug sibutramine, which was supposed to come off the U.S. market in 2010 for safety reasons. Food and Drug Administration hide caption

Photos from Liz Paul's blog entries on Prior Fat Girl. The blog chronicles women's weight loss journeys. Courtesy of Liz Paul/PriorFatGirl.com hide caption

Carlos Romero and girlfriend Kate Rowe sit down for a meal they cooked together. Two years ago, Carlos Romero weighed 437 pounds. Mike Kane for NPR hide caption

When does a diet drug tip the balance for health? iStockphoto hide caption