I used it for 3 months, and lost 10 pounds. I only stopped because I had hit a plateau - but that has happened to me all my life when losing weight, and is worse now that I am older. The only thing that seems to work for me is to use one diet for a couple of months, then switch...otherwise my metabolism catches on and stops ;) (I am 38 years old with a 20 month old daughter...gained 60 lbs when preggers because I was on bed rest). I plan to go back on it when this diet slows (South Beach).
So the scoop on Alli - use the web site for meal suggestions and info. You MUST know how much fat you are eating, and if you go over, you will have problems. I only had on instance of "treatment effects" and it was when I was unsure how much fat was in something when I ate out. You will see some "oil" when you go to the bathroom, but frankly that never really bothered me since I didn't see it any other time....I mean, it is not as though pooping is an especially attractive process anyway, so why does that really matter if it becomes slightly less so in the toilet?
It keeps you really honest about what you eat. Read labels, and in restaurants, ASK if it is not listed. But, if you really follow the program, you won't have problems. Anyone who has had problems (that I have encountered), was not really paying as close attention to the fat content as they thought they were. For example, measure your salad dressing and cooking oil - do not "eyeball" anything!
I am happy to give you more details if you want them...just let me know!
K.