No "faddy" diets every work long term. They may promote a fast way to lose weight, but pose all sorts of health risks. The body needs a variety of vitamins, minerals, fibre, healthy fats..... anything that doesn't provide all of these isn't going to do your body any good. A diet with no calories, sounds particularly dangerous to me!
Also found this on
http://www.healthyweightforum.org/eng/diets/ne gative-calorie-diet/
"The Negative Calorie diet works on the premise that certain foods create negative calorie effects (negative calorie foods), allowing you to lose weight. The Negative Calorie diet is controversial because the theory is not scientifically sound."
It's boring, but true, the best and healthiest way to lose weight is through a balanced healthy diet and regular exercise and that suits your lifestyle.