If you lose weight fast, you will simply trigger your bodies Feedback Loop that regulates metabolism. You will turn it down and make it EASIER to gain weight in the future and if you're losing weight fast, you surely aren't making changes that are life time changes so as soon as you stop doing whatever it is you are doing to drop weight fast. Boom, you will baloon back up.
This is what they call the Yo-Yo dieter. Always taking it off and putting it back on, because you haven't learned the WHOLE TRUTH about weight loss. You can learn it in my new e-book, which I wrote specifically becuase ther was nothing out there to help people like you.
If you're really interested in losing weight as fast as possible while keeping it off, I explain why and how my weight loss program works in my new weight loss and diet program.