Russell Crowe trying to lose weight

Los Angeles - Russell Crowe is on a mission to lose weight.

The Oscar-winning actor - whose weight has fluctuated over the years - has started a tough exercise regime in a bid to get himself into shape.

Writing on his Twitter page, he said: "First ride in quite some time. Sore legs, sore ass, be worse tomorrow and the next day. (sic)"

The father of two then told one fan: "If i stop exercising my body tries 2 return 2 its heaviest weight. (sic)"

The Gladiator star is on a 105-day training period, which he admits is taking its toll.

He said his diet plan includes "taking in roughly 2400 cal/ 2600 cal incl all beverages (sic)", as well as tough workouts, one which left him declaring: "i'm toast (sic)"

In 2009, it was revealed Crowe, 47, was using a state-of-the-art gym on the set of Robin Hood to avoid gaining weight.

A source said: "Russell is a professional. He knew he was cast to play Robin Hood, not Friar Tuck. He knows he has to stay fit."