That's a lot in a short amount of time especially since you don't have a lot to lose. But you could aim high and whatever you lose will be great. Put yourself in boot camp for 4 weeks (pretend one). Stick to 1200 calories a day. Focus on lean protein, lean dairy, fruits and veggies. Cut out all processed foods Be really strict with your tracking and measuring (it's only 4 weeks)! Start an exercise plan. Do a strength training/circuit training dvd a few times a week and cardio 5x a week. If you have an event planned in 4 weeks that you are aiming to look good at, short term is good. It's not always a good idea to put a time limit on weight loss because you just don't know how your body is going to respond and lose. You don't want to get disappointed. But if you want to work hard for 4 weeks, give it a go. Good luck!