50 Cent has hired a personal trainer for his 12-year-old son because he is overweight.

The 34-year-old rapper recently lost 54 pounds in nine weeks to play a cancer-stricken American football player in upcoming drama Things Fall Apart. Losing so much weight meant 50 had to learn a lot about health and nutrition, and he was shocked to realise that so many people he knew were overweight or obese.

The star is now committed to fighting childhood obesity, starting with his own son Marquise.

"My little boy has got a little weight on him, so now`s he got a personal trainer - but he wouldn`t have a personal trainer if I wasn`t in the financial space that I was in," 50 explained to In Touch Weekly magazine.

50 has now launched a youth fitness campaign through his charity group the G-Unity Foundation. He says seeing his own son struggle with his weight has inspired him to change the way all young people approach health and fitness.

"It just makes me more conscious of it. I think it`s just the times: The technology is making them more comfortable sitting there playing video games and watching television," he explained. "They should do things that more physical.

"They should go out and meet people instead of going on a social network all the time. They?re conditioned to look at a photograph and say `Make me your friend.`"

Marquise is 50`s son with his ex-girlfriend Shaniqua Tompkins.
sections: Celebrities