By Genevra Pittman NEW YORK (Reuters Health) – Half of parents with an overweight or obese child think their kids are slimmer than they actually are, according to a new review of past studies. In 69 studies of more than 15,000 children, researchers found many parents with an overweight child thought their son or daughter was at a healthy weight or below. “We know that parents play a very crucial role in preventing childhood obesity, and interventions are most successful if they involve parents,” said Alyssa Lundahl. “Previous research has found that when parents’ perceptions are corrected, they do start to take action and encourage their children to become more active and maybe turn off the TV and go outside and play,” she told Reuters Health.