The concept of “food deserts,” which described the scarcity of grocery stores and other sources of healthy foods, was a popular target a decade ago for the cause of obesity in low-income neighborhoods. Now, Ken Kolb, professor of sociology at Furman, says food deserts were a red herring. In his new book, “Retail Inequality: Reframing the Food Desert Debate,” Kolb argues the problems are much more complicated. He writes about this in an essay on the website Talking Points Memo.