Competition is cutthroat among Japan's thousands of pop-idol wannabes, but a unique concept is winning fame for a band of "chubby" girls deploying their cheeky cuteness to combat prejudices against obesity.

Despite one of the lowest rates of obesity in the developed world, Japan has a growing number of underweight young women, who rely on excessive dieting to satisfy society's emphasis on being slim.

Heavy people are the frequent target of jokes in the media and use of the derogatory debu, or "fatso", remains common.