I have done about 5 of the MCs. This time I only gained back the food weight of 4 pounds. It did not mess up my metabolism because I got enough calories to prevent it. You will gain it all back if you over eat afterwards. I am into Vegan now, sometimes breaking it.

It's really just your Resting Metabolic Rate that goes down while on any kind of fast because your body's not using energy to digest food. But it's a small decrease and the Master-Cleanse has plenty of calories to keep your body using energy as it normally would. Exercise will greatly improve your RMR--even just a walk or some small dumbell exercises while watching TV. If you cut the syrup by half, you will see tremedous weight loss within the first few days, especially if your body weight is a tad high--It uses more energy to function. The Master-Cleanse is great but you can't overindulge afterwards--just like any other diet or fast or you will get sick. I find fasting to be very spiritual and enlightening so grab some good books to read during your journey if you can. Good luck and always come back here for support! There's also a Fasting for Weight Loss forum.