Robbie Williams and Gary Barlow are competing with each other to see who can lose the most weight.

Williams told The Sun: 

"Me and Gary vary in weight. We go up and down by the week.

"Gary and the boys were at my house in Los Angeles last week when Gary turns to me and says, 'I won't be needing these clothes soon, do you want them?' - because he's going on a diet.

"That was the day I thought, 'Right, if you're eating a lettuce, I'm eating half a lettuce.' "

"There is now a serious game on to see who can get the thinnest for the tour."

Watch Robbie Williams and Gary Barlow speak to Paul O'Grady below: