Unless you completely change your diet I would advise against alli. One of the major side effects is anal seepage...if you eat a lot of fat in the diet your constantly going poo, not just that you have to run to the bathroom, that it actually just drips.
I used the weighdown diet and then now I am going to go back on it again. I started gaining weight after coming back to America from Papua New Guinea and Australia....we have a ton more refined unhealthy food here....and then had my 3 babies. So I put on some weight and in order to be able to get a tummy tuck I need to lose some weight so I am going to start that again today. Try this one first and then go from there. There is not pills to take and you don't "diet" you just change your lifestyle and the weight falls off. (At one point I was losing 5 pounds or more a week).