Walter Willett finds it useful to present dietary information in pyramid form, with the broad base representing exercise and foods to emphasize and the small tip showing foods to avoid. “It’s simple,” he says. “It gives you a sense of priorities.” But he argues that the federally sanctioned USDA Food Guide Pyramid is deeply flawed. “The thing to keep in mind about the USDA pyramid is that it comes from the Department of Agriculture, the agency responsible for promoting American agriculture, not from agencies established to monitor and protect our health,” he says. Willett’s alternative Healthy Eating Pyramid draws a distinction between good and bad fats, between whole-grain and refined carbohydrates, and between healthy and problematic sources of protein. It also moves potatoes out of the vegetable category altogether. “Potatoes should be counted as starches. They are converted to glucose as fast or faster than pure table sugar,” he says. —B. L.