Pop star Kelly Osbourne's has revealed her dramatic weight loss is due to a thyroid problem and she is refusing treatment in case she puts it all back on. The daughter of rocker Ozzy Osbourne was thought to have shed 13 kilograms (2 stones) through dieting and exercise - but she confesses the health problem is responsible. Osbourne is quoted in British newspaper the Daily Mirror, saying, "Forget all that healthy-eating bulls**t. "I have a thyroid problem which means I s*** all the time. "My doctors want me to start taking steroids for it but f**k that. I don't want to put all the weight back on again."