I used it for five months in 1999 and lost 56 lbs. I went from 236 to 180, and am 5'10" tall. I also walked/jogged three miles around green lake every day and did tae-bo about 4 times per week (about 40 min. aerobics). I stayed at 180 for about a day and a half and went back up to 200. I stayed there until I became preganant in 2003 and then gained ALL the way back up to where I am now at 241. It does work ... although you're often hungry.
I remember what it taught me though, because you only get that one meal a day, you really learn to listen to when you're NOT hungry anymore. So, after I got off it I was better at being tuned in to my body. Toddler years, however, you only get to listen to the kid. :-) He's four now, so I guess it's time to listen to my body again.