The 75-year-old veteran musician said now he raises a toast only after he is done with the gig, reported Daily Express.
"I don't eat or drink before I go on because I sort of like to feel light. Then afterwards I can get heavy and have a drink. But before I go on I don't do that.
"I do have little sort of snacky things in the dressing room that I might just grab like chocolate covered raisins and equal amounts of salted cashews," McCartney said in a Facebook Live with Australian musician Tim Minchin.