You might have seen the adverts....this stops you from absorbing fat and so you are supposed to lose weight:
Fat is high in calories but if it isn't absorbed, it can't contribute to weight gain. The unabsorbed fat passes naturally out of your body in your stools.Note you will also avoid all the vitamins that are in the fat.
Barry Groves has discussed this stuff before:
If you want to lose weight using alli, you still have to eat a low-fat diet and exercise, which is probably what you are already doing and, if you're doing that, you don't need alli. If you don't also cut your fat intake, you'll spend a lot of time sitting either on the toilet or in very messy, fatty pants. The fat that alli has stopped your body absorbing has to go somewhere; it leaks out of your nether end!
There are lots of nasty side effects (see this woman's experience) but here is a big one:
The US Food and Drug Administration has received more than 30 reports linking the drug to serious liver injury.Forget the fat phobia - fat is good for you.