A Water Fast will give "faster" results. Especially when it comes to "detox crisis". The Master-Cleanse is better for those of us who are toxically overloaded, and also provides nutritional support. You will have more energy, and your metabolism will be better.
I am starting another Master-Cleanse on Monday. I usually lose about 2 pounds per day for the first 5-7 days; then slow to a pound every day or two. I am able to work out on my treadmill most days, and my headaches are more manageable.