Watch Generation Iron Natty 4 Life Online Free. This next chapter in the flagship Generation Iron film series explores the controversial world of professional natural bodybuilding by following top pros competing for the Natural Olympia title in a league dedicated to ensuring all competitors are free of performance enhancing drugs. With drug use evolving at a rapid pace across sports and entertainment, natural bodybuilding as a whole has been criticized and questioned. Can the league guarantee that these competitors are truly natural?