Adrian Sutil revealed on Friday that he went without food for two days in a bid to lose weight and race in Formula One this year.
The 31-year-old German, who drives for the Sauber team, told German magazine Auto Motor und Sport, that he only drank water for two days as he tried to lose weight.
At the Circuit de Catalunya, ahead of this weekend's Spanish Grand Prix, he added that he found the experiment interesting.
"I was testing it a little bit here and there," said Sutil. "Two days, no food, only drink. It was not easy, but interesting (to see) what the reaction is.
"I could feel there was a limit where I didn't have the power any more, the strength in my mind. It's just important to know your body quite well. I tried it, but I'm still alive so don't worry too much."
According to Auto Motor und Sport, the German is 13 kilos heavier than his Mexican team-mate Esteban Gutierrez.
The new Formula One regulations for 2014 have put a premium on drivers losing weight to help the teams get their cars down in weight.
Sauber has managed to cut "substantial" weight from its Ferrari-powered C33 for the Spanish Grand Prix this weekend.
Gutierrez is reported to be below the FIA's mandatory weight limit so allowing the team to add ballast around the car to improve handling.