If you want to lose weight fast, you need to really be on point with your diet.
Cut out all processed foods and get used to filling yourself up on vegetables/salads.
Have 6-8oz of lean meats along with your salads and a fist sized portion of carbohydrates (brown rice or yams for example).
Drink 8 glasses of water a day...
Have fruit and some nuts(not too many, they are calorie dense)...
Bottom line though..count your calories to ensure you're on point and don't drop lower than 1,200/day.
Add up to 1 hour of cardio/day to burn another 500 calories/hour.