Presenting the only non-prescription FDA approved weight-loss supplement, Alli from Glaxo Smith Kline. Alli works through a very different route than other fat-loss pills. Instead of chemically speeding up your heart and metabolism, it works in your digestive system so you don't get the jittery feeling that can keep you up at night. Pound for pound, fat is the most calorie rich thing you eat, and Alli works to limit the negative impact it has on your weight.It works by preventing your body from digesting about a quarter of the fat you consume. The undigested fat passes harmlessly through your body, and your body still digests carbohydrates and proteins without any trouble. This isn't a free pass to eat all the junk you want, you still need to limit your calorie and fat intake. That being said, Alli will help you lose 50% more weight than dieting alone. Now that's a weight loss claim you can count on.