???

Is the Dukan Diet really effective?
Or is something wrong with my body?
I have those huge constipations, I haven't been to toilet since I've started this diet. I do everything as I am told, I eat those bran (maybe a little too much?), I drink about 3 litres of liquids, I walk at least for 40 minutes a day and still... nothing. I feel like my stomach is a one big stone. It's quite uncomfortable and when you're in this state for 4 days, it's starting to really bother you and make you anxious and edgy. And how can it be healthy to hold food in your body for four days? You become a stale rubbish dump. I don't think this is really the way to lose weight if you think it through.