
The best method for speedy but healthy FAT-loss (as distinct from just
losing weight) is to eat LOADS of protein, lots of veggies and good fats, and no starchy or refined carbohydrates. Combine this with daily exercise (weights or interval), and you will burn a lot of fat without damaging your muscles or metabolism - I lost a dress size in two weeks last time I did it, and it was all fat that came off.
For this regime, forget calories and forget your weight.