The popularity of the Atkins Diet and the South Beach Diet -- both of which limit carbohydrates -- plus the proliferation of low-carb processed foods can be seen as evidence that carbs have become the new bogeyman of the American diet. But what is the science behind this low-carb revolution? And do these diets work? Here are the views of Dr. Arthur Agatston, author of The South Beach Diet; journalist Gary Taubes; nutritionists Marion Nestle, Jeanne Goldberg and Aviva Must; and Dr. Dean Ornish, author of Eat More, Weigh Less.

During the 1990s, the low-fat craze changed the way Americans eat, and yet they got fatter than ever. By 2001, one-third of the American population was overweight. Here, nutritionists Marion Nestle, Walter Willett and Jeanne Goldberg, journalist Gary Taubes, and Dr. Dean Ornish, author of Eat More, Weigh Less debate the reasons behind the disparity between the low-fat message and America's obesity epidemic, and assess whether a low-fat diet is still the way to go.

The food pyramid that was released by the U.S. Department of Agriculture (USDA) in 1992 quickly became a recognizable nutrition symbol for Americans. However, during the same period of the 1990s, Americans gained more and more weight. Is the food pyramid to blame? Here, Walter Willett, M.D., author of Eat, Drink and Be Healthy; Jeanne Goldberg, professor of nutrition at Tufts University; Marion Nestle, chair of the Nutrition Department at New York University; and Dan Glickman, former secretary of agriculture, offer their criticisms of the food pyramid and discuss the politics behind its creation.

Here, Dan Glickman, former secretary of agriculture, and nutritionists Marion Nestle, Walter Willett, Aviva Must and James Hill offer their suggestions on how to confront America's worsening obesity epidemic.