A no carbs & suger diet works very well if you wanna lose weight fast - (Kind of like the Atkins) You can only eat nuts, veg, meat and dairy (but not milk because lactose is sugar).
Basically it fools your body in to fueling itself with the fat it has in storage - the weight flys off very fast, but its more of a trick than a diet.
BUT! this diet has many downsides.
-Its not a very healthy or natural way to lose weight.
-On the first few days you will feel like crap as your body deals with the sudden changes and is forced to re-tune itself.
-Drink as much water as you can or you WILL get the worst constipation ever!
-The effects only last as long as the diet, as soon as you come off the diet (and even if you continue to eat sensibly) most of the lost weight will start to return.
-You only get one shot!, it is very effective the first time you try it, however if you stop the diet and then try again, it will never work as well the second time around. It seems that our digestive systems can only be fooled once