Australian star Shane Warne has launched into a new diet, in which butter and beer are banned, in a bid to ensure he stays at his cricketing peak.

The 32-year-old leg-spinner, still the best in the business, has already lost nearly 12 kilos.

Warne, in England to promote the paperback version of his autobiography, is slimming down to ensure he stays at the peak of his powers for the upcoming double bill of the Ashes followed by the World Cup in South Africa.

In an interview to English newspaper The Independent on Sunday, Warne said: "I looked at the international programme and what lay ahead and it's an unbelievable schedule.

"I've been training really hard, dieting, cutting out butter, minimal cheese and pizzas.

"I still have chips occasionally, but not with every meal - no beer, I'm only drinking wine.

"I'm into fruit, three litres of water a day, soups and salads. I'm actually getting some muscles which I'm starting to enjoy."

Worryingly for England and any World Cup opponents, he is also keen to talk up his form.

"I think I'm finally back now to the way I used to bowl, which is very, very pleasing," he said.

"I'm finally beginning to understand my bowling a lot more, how to get batsmen out rather than just bowl big, turning leg-breaks.