I lost 17 lbs on it, in about 3 months, and I stuck to the calorie and fat intake religiously. I realize that amount isn't amazing, but it was good for me. I probably would've lost more like 12 lbs without it.
It is imperative that you eat the max fat grams allowed, without going over, and that you know EXACTLY what the calorie/fat content is in EVERYTHING you put in your mouth, and journal it.
If you don't eat enough fat, the pill won't absorb as many calories, and you won't get maximum benefits. I found it hard at first to eat 1200 calories a day, AND about 40 grams of fat. I was used to relying on things like Lean Cuisine, low fat snacks, etc, and they just do not have enough fat grams to make ALLI work effectively. To combat this, I would add 1 cashew for each gram of fat I needed to add.
I had no "treatment effects", but as I said, I stuck to the fat gram guidlines, without exception. It's hard to do when the inevitable birthday party, holiday, party, etc..comes up. So, it DOES keep you in line, so to speak, because you dread "effects", but I think it's hard to stick to because you should be able to eat a small piece of pizza or birthday cake once in a while, KWIM? You can NOT on this plan.
In short, it's a great way to keep you honest, and does yield results, but the inability to EVER have a "treat" gets old after a few months.
Hope that helps
If you try it, I highly recommend you register your product on their website and join their forum, as you will have questions.