I NEED to loose 20 pounds?

Anyone got any idea how mila kunis lost twenty pounds for black swan? Any tips on what sports to do? I do brazilian jiu jitsu twice a week, tae Bo every day, and am going to start fitness pole dancing soon as well. Any one know of good diet tips? How many calories I should intake? Im 17, weigh on a good day 125, bad.. 130 and am 5'5. How much weight should I need to loose to be skinny? I'm not FAT, but I'm also not Angelina Jolie (a twig) and I want to be a twig.