Heavyweights is a 1995 comedy film about a fat camp for kids that is taken over by a fitness guru named Tony Perkis (Ben Stiller, who would later play a similar role in 2004's Dodgeball: A True Underdog Story).
As school ends for the summer, Gerald Garner (Aaron Schwartz) is sent by his parents to Camp Hope, a weight loss camp for boys. Despite worrying at first, Gerry makes friends easily at camp and learns that Camp Hope is actually a lot of fun and won't be nearly as bad as he thinks. (As one veteran of the camp put it, Gerald is "not the fat kid, everyone's the fat kid.") He also discovers that the other campers have smuggled in enough junk food to easily stave off the hunger pangs and probably counteract any weight loss that the camp programs cause.
But all is not well at Camp Hope. The first night of the summer brings the revelation that the original owners of Camp Hope have entered bankruptcy and the camp has been bought by fitness entrepreneur Tony Perkis (Ben Stiller), who announces his plan to make the camp's new exercise regime into the top weight loss infomercial in the country. Tony tries to make himself seem like someone the campers can relate to, saying that he was a fat kid when he was younger too, but his methods of motivating the campers border on psychotic.