Are some fats in foods more likely to end up as harmful visceral fat than as less-harmful subcutaneous fat? To find out, Ulf Risérus, associate professor of clinical nutrition and metabolism at Uppsala University in Sweden, and his colleagues devised what some have called “the muffin study.” “We had lean people eat, on average, three muffins per day on top of their usual diet,” he explains. That meant that each participant ate 750 more calories a day than he or she needed. “We wanted a moderate—not an extreme—increase in calorie intake to represent the normal situation in the Western world, where most people gain weight after their 30s.”