5.JANET JACKSON Shedding 60 lbs. through five-day-a-week workouts took the 40-year old pop star from heavy to hot this year. 4.ASHLEE SIMPSON Jettisoning her old punk style and her old profile the singer debuted a sleeker, sexier look this summer. 3.JENNIFER HUDSON After gaining more than 20 lbs. for her Golden Globe-nominated role as Effie in Dreamgirls, the former Idol shed the weight and embraced a more glamorous red-carpet style. 2.CAMERON DIAZ The quintessential blonde California girl threw everyone for a loop dyeing her normally sunny locks a dark chocolate brown. 1.WHITNEY HOUSTON Just two weeks after filing for divorce from husband Bobby Brown, a shockingly glam Whitney Houston stepped out with music mogul Clive Davis, sparking hope of a major comeback.