I don't know anything about this stuff but having been around gyms for a year or two I would be highly skeptical that you will get those results unless everything else is perfect and you're genetically super man. What it actually says on their site is:
"as individuals differ, so will results-numerous people have experienced extraordinary results (lean body mass gains of up to 7 to 10 lbs in as little as 10 days)."
Kind of a slick catch all way to say that one humongous juice takin' guy got this kind of results. Your milage may vary.