Forget about chocolate and greasy foods. Eating too much refined bread and cereal may be the true culprit behind the pimples that plague many a youngster, reports Britain’s New Scientist magazine. That’s the theory of a team led by Loren Cordain, an evolutionary biologist at Colorado State University in Fort Collins. Highly processed breads and cereals are easily digested. The resulting flood of sugars makes the body produce high levels of insulin and insulin-like growth factor (IGF-1). This in turn leads to an excess of male hormones. These encourage pores in the skin to ooze large amounts of sebum, the greasy goop that acne-promoting bacteria love. IGF-1 also encourages skin cells called keratinocytes to multiply, a hallmark of acne, the team say in a paper that will appear in the December issue of Archives of Dermatology.