Consider this. Weight gain is basically one of the side effects of lifestyle and poor eating habits. IF you are planning to change those things PERMANANTLY, The Master Cleanse can eliminate a lot of the old built up toxins and some of the extra weight that has built up over a lifetime. The Master-Cleanse can kick start your body into better health, eliminating some of the toxicity, so that as you begin a better diet regimin, you are starting off with a slightly healthier body and maybe a few less pounds.
It's not a panacea to weight loss however. It's just the beginning of a lifestyle change. The biggest issue with doing this program strictly for weightloss, is not having a back up plan already in place to keep the weight off. And even WITH that, you are fighting an uphill battle since fasting dramatically decreases your metabolism. So, you just need to get your metabolism back in place AND continue to eat healthy afterwards, otherwise weight gain is inevitable, if you continue to eat the same way you did before.
10 days is not long enough to change the program in your subconscious mind to eat healthy. So while you may get great inspiration for 1 or 2 days on this diet, one thing that may happen is that once you are able to eat real food again is that you will be faced with real temptation again, and THAT, I tell you is where the real work begins.
Start NOW to change your views about food and how you will continue to eat. Also, incorporating some kind of exercise; including cardio and weight training, or even yoga or pilates ... at least 5 days a week is a must to keep the weight off.
My plan for example as soon as I am off is to do body for life. I have already done this program many times and it works for me. I admit, I have had trouble keeping weight off for long periods of time, something always comes up for me. But I continue to learn from my mistakes. Right now, I realize I can't eat just like my 6 foot tall skinny fiance, who's 9 years younger than me, when I'm only 5'3". But, I thought since I was preparing for a marathon, running 25-45 miles a week (which I completed 3 months ago) that I could eat whatever I wanted. LOL! And I somehow managed to GAIN about 15 pounds over 9 months between getting engaged and after the marathon. So, now I recognize AGAIN that it is a combination of both. You can run all you want but if you don't eat right, it'll come back. You can eat right all you want, but if you don't exercise, same thing. It's a balance.
Anyway, so, yes, you will lose weight during the cleanse, no question ... but, what will happen afterwards ... that weight will come back so fast your head will spin if you don't create an action plan to keep it off now.