Demi Lovato feels most beautiful without make-up.

The US 'x factor' judge - who has previously battled drug addiction - used to think she looked her best when she was on a red carpet but now believes she is her most confident when she isn't wearing cosmetics.

She said: ''I used to feel my most beautiful when I was on the red carpet or at events or something where I'm all dolled up.

''Now it's when I'm able to hang out with a guy without my makeup on or lay on the beach with no makeup on and not even worrying about what my hair ... When I'm confident enough to show myself without makeup on, that's when I feel my most confident.''

Demi rarely treats herself despite her millions, and once purchased a pair of designer boots she has never worn.

She told Self magazine: ''I was at the mall and was like, 'You know what, I worked really hard this year. I haven't really ever bought an expensive pair of shoes before. I'm going to go for it.

''So I purchased them and I never wore them once.''