File-This Aug. 25, 2014, file photo shows Kristy Lewis, director of the Paducah Preschool Head Start Program handing out snacks Keegan Walker, a student at Clark Elementary at Robert Coleman Park in Paducah, Ky. Head Start programs have been shown to help poor children do better in school, but they may also help them fight obesity, a study suggests. During a year of Head Start preschool, obese and overweight children were much more likely to slim down than comparison groups of kids. (AP Photo/The Paducah Sun, Ellen O'Nan, File)