The 41-year-old "How Deep is Your Love" hitmaker has stripped back his eating regime to just fruit drinks and freshly squeezed vegetables in order to shed some weight, reported Daily Mirror.
"Robbie's found it harder to keep the pounds off and maintain his body since giving up smoking a couple of years ago, so he has to work harder in the weeks leading up to performing if he wants to be able to look and perform at his best.
The singer is also hitting the gym and doing weights to get back in good shape for the gig.
Williams' European stint ended in August, and he has since been at home with wife Ayda and children Teddy, three, and Charlton, who turns one this month.
