By Gene Emery NEW YORK (Reuters Health) – Children who are overweight when they start school are far more likely to be obese by the time they become teenagers, according to a new study of nearly 8,000 children. Overweight five-year-olds were four times more likely to be obese by age 14 than children who started kindergarten at a healthy weight. “Half of childhood obesity occurred among children who had become overweight during the preschool years,” researchers led by Solveig Cunningham of Emory University in Atlanta wrote. “If we’re just focused on improving weight when kids are adolescents, it may not have as much of an impact as focusing on the preschool-age years,” Cunningham told Reuters Health.