He cruised into the quarter-finals with a 13-7 victory over Ryan Day on Monday and hailed the impact his diet change has had on his energy levels during the marathon 17-day tournament in Sheffield.
O'Sullivan revealed he will go 16 or 17 hours without eating before refuelling before matches.
"It feels great, I feel good. I'm 48 and I feel energised. If I eat too much I get really sluggish," said O'Sullivan, who has also credited his love of running for keeping him both mentally and physically sharp.
"What I do is I try to eat right. I'm intermittent fasting for this tournament because it gives me more energy,"
"There's certain things I do and it doesn't necessarily mean I'm going to win, I just need every little advantage I can get at this stage.
"This is a tournament of endurance, stamina and concentration. For me, intermittent fasting just gives me a bit more energy."
O'Sullivan will face either Jack Lisowski or Stuart Bingham in the last eight.