Hi Karen,
You brought up a very good topic. Meal replacements are an effective tool for weight loss and maintenance. The key is finding ones with the right nutrients to help you feel satisfied. The only nutrient that keeps you feeling full between meals is protein, not fat. If you are hungry 2 hours later it would be a good idea to add some protein to your shake. There is not enough fat in the Slim Fast Optima for you to take Alli with. The shake that I looked up has 180 calories, 6 grams of fat, and 10 grams of protein. My exprience is that 14 grams or more protein usually does the trick for increasing satiety. If you want to add some protein to this you could have some nuts with it. That would also increase your calories and fat so be sure to add the right amount. You would be able to take Alli with it if your fat grams go over 15 grams. Let us know how this goes, Betty Kovacs, MS, RD