Since Britney Spears emerged from Promises Malibu Residential Treatment Center on March 20, the formerly bloated and sallow-faced pop star has been looking rosy-cheeked and fitter than ever. So how did Spears transform herself so quickly? Well, for starters, no more Malibu rum and cokes with fast-food chasers. These days, Spears, 25, is sticking to a more body-friendly regimen. After five hours haggling with lawyers over her divorce in L.A. March 29, the singer hit local eatery, The Bridge, and drank sweet iced tea and mineral water. Then, two nights later in Vegas, Spears dined on sushi and vegetable dumplings (and more iced tea) with pals at Tao restaurant. Indeed a change of pace may have been just what the doctor ordered. "After about three weeks to a month of not drinking alcohol and getting enough water and nutrients into your body, you'll easily look like a different person," NYC-based dermatologist Jeannette Graf tells Us, adding that Spears' healthy new habits help increase circulation to the skin, accounting for that healthier glow. Spears "is repairing her skin, so no more puffy face," says Graf. Her recent workouts have also gotten her blood pumping. Two days after leaving rehab, Spears attended a hip-hop class at Millennium Dance Complex in L.A. "When I saw her, she looked beautiful," instructor Darrien Henning tells Us. Do Britney's friends and family think she's cured? What's Brit's next career move? How is Kevin handling the divorce? For more details on Britney's split from K-Fed and her comeback, pick up the new issue of Us Weekly, on newsstands this week .