Yeah I have to say I agree. Depriving the body of fuel doesn't necessarily make it use fat instead, as alot of people think. It breaks down your muscle mass and uses that instead, which means while you'll be losing weight on the scale, you wont actually be losing fat. Also when you deprive the body of carbohydrates, it needs to lower its basal metabolic rate so it can do its daily functions. This, and the fact that after eating practically nothing the first thing you'll want to do is hoe into a whole bunch of food:P is what stacks the weight back on.
At the end of the day, even if you gain weight back to what you were before the detox, it's fat replacing muscle.
This is just a suggestion, but have you considered doing a raw diet detox instead? you could eat raw foods, have the lemon water and make sure you get enough protein from the raw foods, or buy a good quality protein shake such as musashi (the chocolate is very very yummy, not to mention filling)