Struggling to keep diet?

i need to lose about 15 kgs in 2 months for an operation and i started one today but gave in and ate some junk. i need to crash diet and lose about 2 kgs a week so i can reach my goal. any advice on how many calories and what i can do to keep myself fuller? no comments about "oh crash dieting is bad for you" because i know and i have done it all before. ALL COMMENTS APPRECIATED!