Photo by Luis Monteiro for Grazia

Her photo shoot for the latest issue of UK’s Grazia magazine shows how she went from a size 14 to 10. Leona Lewis underwent a major detox, eating mostly vegetables while avoiding all processed food and drinking nothing but water, for a whole month.

She admitted to becoming more conscious about her figure when she became a celebrity. “Now I sometimes feel like I can’t wear certain things, so I’ve stopped looking at photos of myself,” said the 24-year-old singer. “You become more self-conscious.”

A curvier Leona Lewis in December 2008.

To see more photos of Leona’s more toned figure, grab your copy of Grazia’s March issue, out this week.