There are also many different ways to fast. As you know, some people choose water only, some choose juice, some choose the MC. It's natural to lose water first. The body will turn to both fat and muscle for fuel. This will happen even when on a restricted diet. To me, fasting is part of my lifestyle for health, healing and maintenance. Because I incorporate fasting and healthy eating into my lifestyle, my weight stays low. The metabolism is controlled by our thyroid. We can increase our RMR by gaining muscle and speeding up the body's thermostat when exercising. When we aren't working so hard, our RMR falls a little. But you won't "stop" your metabolism by fasting. You can only do that with a thryoid problem. What has happened to me sometimes in the past is that I have fasted and in doing so I deprived my body of certains nutrients so that when I came off the fast, instead of slowly reincorporating them into my diet, my body craved them and I over indulged. That will cause weight gain in anyone, having fasted or not. To prevent deprivation, I choose the MC. I've done water only also and it worked wonders on my health. Bottom line, fasters need our support. Our purposes for fasting may vary, but in doing so we all experience great senses of wellness, spirituality, confidence and inspiration. Just my thoughts for the day on day 11 of a Master-Cleanse fast. Good luck to all!