Alli is an FDA approved OTC weight reduction product available in the form of pills. Its main ingredient is chemical. It's not a dietary supplement, it's not a medicine, it is not a fat burner; it's a fat blocker or fat binder. It's a relatively new product and is one of the popular weight loss products on the market nowadays.
- Since excess calories happen to be the main cause of weight gain and fat is the major contributor of the extra calories, blocking the fat from being digested definitely helps to reduce weight, and Alli aims to do that.

Alli works by blocking about 25% of the fats eaten by you from being acted upon by enzymes so that it's not digested. This undigested fat passes through your body in the natural way. As it prevents fat from being digested, its effectiveness in weight reduction is called as “instant” action.

Alli starter kits suggest that you should limit your meals to a reduced-calorie diet of 15 gms of fat each. If you are not able to restrict yourself to the 15-calorie limit per meal, manufacturer’s literature points out that you may have side effects which the makers of Alli call as “treatment effects”.
It's obvious that to avoid the “treatment effects” successfully you may have to drastically alter your diet and reconsider the way you have your meals now.

These limitations on your life style are bad enough, but if you happen to stray to the wrong side of the 15 gm-“barrier”, you may have very unpleasant results to face. Alli literature refers to these consequences as “treatment effects” but in layman’s simple language it means that you may suffer uncontrollable bowel movements, loose stools, very frequent visits to “loo”, “farting” with oily discharge, etc..

Alli claims of helping you to lose weight are not in dispute here, since it has been clinically tested and approved. What we wish to notice is that it's for the individual to determine how far he or she can reap the benefits of Alli without suffering from its side effects.