Lily Allen always feels "self-conscious" when she goes shopping.

The 'Not Fair' singer - who is a opening a fashion rental store called Lucy In Disguise - says she doesn't really enjoying buying her clothes from shops because her weight often fluctuates meaning she doesn't always know what size she is ands up doing most of her retail therapy online.

She said: "I feel self-conscious shopping - my size fluctuates so I never know what to gravitate towards. And because I'm famous people are always staring at me. Timing is important - avoid after school, after work and the weekends when it's just so busy. Have a plan of what to buy and where to shop, I get distracted and come back with things I don't need.

"And don't forget online shopping - I love Net-a-Porter because of the next-day delivery."

However, Lily, 25, does enjoy buying clothes from vintage stores but says the sizing is so different from regular stores.

She told Britain's ELLE magazine: "A size 12 now is different to size 12 in the 70s; vintage shops that divide clothing into sizes may not have taken that into account. If something is too big but you love it, get it taken in - we're going to have an alteration service in our shop."