Rap mogul Jay-Z (pictured) has sparked rumours he's planning to wed longtime girlfriend Beyonce Knowles after he shed several pounds on a strict new diet.

Former Destiny's Child star Beyonce reportedly suggested her burly boyfriend shed a few pounds after pointing out he is 30 pounds heavier than when they started dating in 2003.

The 36-year-old has taken her comments to heart - he has already shed 15 pounds, according to insiders.

A source tells American publication In Touch, "Jay-Z was never fat, but he was getting chunky. Beyonce likes a little meat on his bones, but not too much."

According to the source, Jay-Z's biggest challenge was turning his back on his love for candy.