I had a friend who tried the cabbage soup diet. She lasted about two days and those two days were enough for everyone around her too. The smell was terrible!
And more than that, she was in an awful mood for most of that time. There just isn't enough energy to sustain you in clear cabbage soup. You need to eat some kind of carbohydrate in order to keep your blood sugar up, or you get grumpy.
And the worst part is, if you follow that kind of diet, your body might start burning muscle in order to get nutrients, and muscle burns more calories than other body tissues. So, with lower muscle density, you'll end up putting on weight faster once you finish the diet.
You're better off exercising without changing your diet at all, than getting onto a fad diet.