Boy George Weight Loss -- Not a Big Singer Anymore!

Boy George is half the androgynous man he used to be ... and looks amazing.

The 51-year-old former Culture Club front man -- who has struggled with his weight in the past -- has dropped a bunch of chins and tweeted a pic of his shocking new skinnier look on Sunday.

The slimmer Karma Chameleon also revealed he achieved the dramatic weight loss through portion control and working with a nutritionist.

Boy can finally tumble 4 ya again.