F1 drivers are deliberately dehydrating in order to get their weight down at Grand Prix weekends.

That is the claim of the experienced McLaren driver Jenson Button, who said drivers are so desperate to be lighter that they are cutting out food and water even at sweltering Sepang.

“I am sure they are dehydrating themselves because that is what I was going to do — go in a sauna, steam room, not drink or eat until after qualifying,” he is quoted in Malaysia by the Mirror newspaper.

“I was going to do it and did all year until now, but it is a shame for the guys who have to do it.”

Button admitted he has “luckily” managed to get his weight down to a point at which he is no longer worried about the sport’s 692kg car-plus-driver minimum.

The problem of driver weight has been amplified for 2014 given the much heavier turbo V6 ‘power units’.

“It’s hardcore what people are doing,” agreed Mercedes driver Lewis Hamilton.

“You can go into qualifying a little bit dehydrated. I heard someone was doing that, exhausting themselves,” he added.

Button revealed that, until he got his weight down, he was not eating any carbohydrates, including bread.

Hamilton said: “You don’t want drivers being anorexic.”