She burst on the music scene three years ago lampooning the image-obsessed world of celebrity.
But after taking up an alarming fitness regime, Amy Winehouse has dropped four dress sizes and there are fears that the 22-year-old has succumbed to the pressures of showbusiness.
Less than two years after winning a prestigious Ivor Novello award, the gravel-voiced jazz star appears to be more interested in maintaining an aggressive daily diet of exercise than her career.
"Amy went from being an unknown, middle-class Jewish teenager, to finding herself on the gossip pages of newspapers across Britain," said a source close to the singer.
"Naturally she found the attention quite difficult to handle especially as not all of it was flattering.
"While she doesn't mind people criticising her music, she was devastated when snide remarks about her appearance were made.
The star was pictured earlier this week on a night out wearing a fitted Hawaiian shirt and denim mini-shorts.
With her collarbone and hip bones jutting out, her once shapely legs were a spindly shadow of their former selves.
The source said: "She has experimented with new piercings, hairstyles and even make-up but the single biggest thing that makes Amy feel better about herself is going to the gym.
"For the past 18 months she has been going to her local women's-only gym, for a two hour session, every single day. She is neurotic about it, completely obsessed.
"Amy will do a full cardio, fat-burning workout followed by lots of repetitions, on a relatively light load, on the weights machines. As her body has become transformed, the more weight she's lost, and the more obsessed she has become."
Miss Winehouse's new size 6 physique - down from a well-proportioned 14 - is largely the result of a daily exercise programme carried out at the Fitness First women's only gym in north London's Chalk Farm.
After an initial free consultation with a personal trainer, the singer - whose debut album, Frank, sold over 250,000 copies and won the 2004 Mercury Prize - has amazed staff with her dedication.
Despite being advised to have at least one "rest day" a week, she visits the gym daily, usually going between four and six in the afternoon.
Following a strenuous workout, Miss Winehouse walks the 25 minute journey home, where she showers and changes, before often taking yet another stroll around Camden market.
A spokesman for Miss Winehouse refused to comment