'Yeah, Ive always felt fat!' she admits. 'You see all these people on TV that are so skinny and it makes me think: "My thighs are huge and I have a big butt!"
'Then when Simon said on the first night of the show that he fancied me, I was like "Oh my God!" Hes given me a lot of confidence.'
But would 25-year-old Ruth ever date the newly-single music mogul who's 50 next year?
'No way! First of all Im engaged and if I wasnt engaged hed have to ask a million trillion times for me to say yes. Im a hard woman to get!'
Ruth is gutted that she didn't make it to The X factor final and pines for good pal Alexandra Burke.
'Yeah, I miss her so much,' she says. 'We ring each other like 4 times a day. I know shes sad but shes got to be strong because shes amazing. She has to win this show!
'I talked to Dannii last night, too. We love each other. Shes like part of my family now.'
Ruth will take part in the The X Factor 2009 Live Tour - and dreams of Simon offering her a contract.
'After the tour well know what happens with our lives,' she explains.
'I would love to work with him. I think hes an amazing person and hes so intelligent. I will be seeing him soon because I really want to say thank you for everything that hes done.'
For tickets to see Ruth Lorenzo and your other favourite contestants on The X Factor 2009 Live Tour - and for more info - go to bookingsdirect.com.