The Boomtown Rats frontman, who reunited with his group in 2013, has thrown himself into live performing in the wake of the 25-year-old socialite's death in April, and he insists getting on stage helps him manage his grief, branding it "entirely cathartic".
However, the Irish musician admits he cannot let himself think too carefully about the lines he sings as some of them now seem to be about the tragedies in his own life.
Discussing Boomtown Rats hit Diamond Smiles, Geldof tells ITV host Lorraine Kelly: "There's a song we had that was a big hit, (that) the Rats had called Diamond Smiles... I was writing about a girl I read about in one of the papers, she was a socialite, and she went to a posh party... she went upstairs and hanged herself during the party.
"And it was a tiny little piece (in the newspaper) and I think that somebody said 'She was the brightest of diamonds' and I called the song Diamond Smiles.
"If I really think about those words - and usually I'm in the zone of that song - if I really think about it, it's too bizarre, it's too telling whether it's about Paula [Yates, Geldof's late wife who died of a heroin overdose in 2000] or now whether it's about Peaches, and stuff like that...
"But other than that you know, you're on stage and you're just going for it and you're so engaged in this moment, you're so aware of a crowd but not, you're aware of the band, but not, you're just lost in this moment... When I come off stage I am physically exhausted and mentally clear."