Lose weight from greek yogurt?

I have a have fit into this dress for a special occassion. I have a friend, that happens to be a trainer, that told me if I wanna lose at least 10 lbs in 3-4 weeks I can eat greek yogurts with flaxseed. I have to eat lots of fruits and veggies and drink alot of water and do alot of cardio. I wanna know if anyone has tried this or done anything close to this. I really want anything that will work. they'll be taking pictures and I wanna look my best for such a special occassion.