I did BIWI's low carb bootcamp and managed over 3 weeks. I found the first week really difficult but didn't feel hungry at all and lost 5lbs and 2inches off of my waist.
I am no longer following it, but my diet has become much lower in carbs and sugar and I am drinking more water and adding more veg to my diet.
My reasons for not continuing are:
I was getting more constipated, I suffer with this a bit, but on the diet, despite all the water I was drinking I was going 6-8days without a poo! This tends to make a person a bit grumpy :o
Also, much as I was glad to not need or crave sugar or carby foods I felt sad I couldn't have them and if I did then I instantly felt guilty. Food was not enjoyable anymore and I was becoming obsessed with what I was eating - this was not how I wanted to live.
I was lucky enough that I was doing this more for vanity than health, so have the luxury of saying actually, I don't want to do this. I know that if I ever want to drop the weight then this works though :o