8 weeks. First 2 weeks suck, because you are zapped and you can't get a good pump at the gym. Then your body adjust so then the only thing that sucks is trying to find new foods that you can eat. I ate all the time and was full all day everyday so that was nice. I eased back onto the carbs and didn't gain any weight back because all the frequent meals kept my metabolism up. If you don't ease onto carbs I'm afraid you might blow right back up. I still avoid high carb foods for the most part, but I'm not counting anything.