Weight loss in six weeks?

crocodiles

I recently bought a formal dress for an event at my university, and the zip doesn't do up for the last two inches, if that makes sense. I'm looking for ways that I can lose as much weight as possible - aiming for around 7-8lbs in six weeks? I'm going to be sticking to a 1,000 calorie-a-day diet, which should make a good impact, but does anyone have any other tips? I try to go to the gym as much as I can but I have exams soon so I won't have a lot of time. Thankyou