Gibson's girl puts star on diet

Mel Gibson's girlfriend has made him embark on a tough new diet and fitness regime.

Oksana Grigorieva - who is 14 years younger than the 53-year-old actor and director and is pregnant with their first child - is keen for Gibson to eat more healthily and convinced him to undertake a rigorous exercise plan to get trim.

Gibson was reportedly overheard telling a pal: "It's all very tiring. I hope it's all worth it in the end."

Gibson's wife of 28 years Robyn filed for divorce last April citing "irreconcilable differences".

The couple, who have seven children together, released a joint statement saying: "Throughout our marriage and separation we have always strived to maintain the privacy and integrity of our family and will continue to do so."

Russian beauty Girogrieva and Gibson's child is due this autumn.