Hi there! From what I understand alli blocks a small percentage of the fat that you eat, so it doesn't get absorbed into your body. It doesn't suppress your appetite or anything like that (I wish!). When you eat over the suggested amount of fat grams per meal, you have the "treatment effects" which I guess can be horrifying. My sister tried it but didn't change how she ate and had some bad experiences, if you know what I mean. I haven't had any problems, but I've followed the plan religiously for almost 4 weeks (lost 14 pounds). It's not hard for me at all and I bet if you eat right, you'd be fine taking the alli. You have to have some fat in your diet for your body, so they don't want you to completely eliminate fat. The website is pretty good for getting more info - good luck to you if you do decide to try it and let us know how it works for you!