New York (ANI): Pop diva Britney Spears is so obsessed with her looks that she doesn"t even workout without her make up. The 'Toxic" singer was seen all decked up running on a treadmill and doing crunches at the Mondrian Hotel in Hollywood along with her mother, who used dumbbells, reports the New York Post.

According to a witness, Spears worked up such a sweat, "she looked like Heath Ledger as the Joker". The 28-year-old beauty has also changed her blonde hair into brunette. She tried to sneak into the hotel unnoticed, but unfortunately even with her new hair colour she was easily recognized.