This year, 30,000 Scouts ages 12 to 20 and their leaders were required to meet a threshold for body mass index and other health factors before being allowed to participate. Jamboree applicants with a BMI â€” a measure of body fat determined through height and weight â€” of 40 or higher were deemed ineligible. Those who fell between 32 and 39.9 faced providing additional health information to Jamboree medical staff.Nationally, about 17 percent of children ages 2 to 19 are considered obese â€” triple the rate from a generation earlier, according to the Centers for Disease Control and Prevention.â€śWe required a level of fitness in order to come to the Jamboree that we havenâ€™t required before,â€ť McCarthy said. â€śAnd that has motivated an enormous return in terms of both kids and adults getting serious about improving their health.â€ťSoon, the Scouts will know why. Besides offering a whole lot of fun, dozens of venues will test their physical skills and fitness. At some point during the Jamboree, every participating Scout will be asked to take a 3-mile trek up a mountain.Their reward: A barbecue waiting at the top.