Gerry, an overweight boy, is sent to Camp Hope, a summer camp for overweight kids, run by kindly owners, Harvey and Alice Bushkin. Initially despairing about attending, Gerry soon makes friends and starts enjoying the various activities and the camaraderie of his fellow campers. However, the camp's atmosphere takes a drastic turn when the Bushkins' financial troubles force them to sell Camp Hope to Tony Perkis, a cruel and fanatical fitness freak. Tony plans to turn the camp into a weight-loss boot camp, complete with grueling exercise regimes, unhealthy competition, and severe punishments.

Tony's harsh methods and severe restrictions lead to rising tensions among the campers and staff, who resent his oppressive rule. Gerry and his friends, including the loyal instructor Pat, begin devising clever plans to undermine Tony's authority and reclaim their beloved camp. Their resolve strengthens as they witness Tony's growing obsession with producing a weight-loss infomercial at their expense. Determined, the kids unite to resist Tony's tyranny and bring back the fun and supportive spirit that once defined their summer haven.