This is the long answer :)
--Chelsea Kissinger, Family Nurse Practitioner Candidate, RN
Alli (drug name Orlistat 60mg) does work by helping you lose weight, but it acts differently than other over-the-counter diet pills. Alli doesn't work as "quickly" as other diet pills work, because it actually helps you get rid of fat.

Fact: It is not possible for your body alone to get rid of more than 2 pounds per week of actual fat (although this rarely happens), because of a limit of your body's metabolism, or ability to break down fat. You may see the scale go down more than that, but that also relates to losing water weight or muscle weight.

Some users have reported losing about 1-3 pounds per week if you follow the Alli Program, which also includes choosing more active recreations, a healthier eating pattern, and reacting positively to change. Alli will not work much if you do not follow the program!! You may lose more weight than this, or less depending on many factors. All in all, the general rule is whatever you lose in a week you will lose about 2 times that if you follow the Alli Program. It is by no means a quick fix, but if you are ready to change some of your habits, it is in my opinion, an excellent program!!

Here's a little more information about Alli and diet pills:

Most OTC diet pills work by adding a stimulant, like caffeine, which speeds up your body's function, and thus might make you lose some weight but will speed up your heart rate, blood pressure, and might make you jittery or nervous. Others have a diuretic, which just make you urinate a lot of water, so you are just losing water weight, not fat weight.

So, how does Alli work? First, a little background. Normally, your body absorbs fat from food in your intestines, but first it has to be broken down by proteins into very small triglycerides and cholesterol (You've probably seen these when you go to get your cholesterol checked). Alli works by binding to about 1/3 of the fat from your intestines, so that it cannot be broken down and absorbed into your blood stream. So, this is the reason why you take Alli when you eat a meal.

Because the medicine works in this way, you will expect to have more fat in your poop. The more fat you eat, the oilier and more like diarrhea it will be. In medical terms, we call fatty stool steatorrhea. Sometimes this stool can leak out or smell bad, and you may have more gas if you eat a fatty meal. These seem like unpleasant side effects, but it helps you to recognise how much fat is in different meals, and if you eat a healthy meal, you won't have these side effects.

Also, because you are not absorbing as much fat, your vitamins that are carried in fat may decrease. I call these "ADEK," which is vitamin A, vitamin D, vitamin E, and vitamin K. You MUST take a MULTIVITAMIN AT BEDTIME so that you do not lose these great nutrients :) !!!

Some Extras (not really relating to Alli, but being healthy without guilt or without feeling like you are denying yourself the good stuff)
-try not to weigh yourself for the first month, the scale isn't going to tell you at this stage what you are actually losing. A more effective way of checking if you are becoming more fit, and having less fat, is measuring your waist. If you look at the scale, you may get discouraged. With exercise, muscle weighs more than fat, so you may feel better and leaner, but your scale might not reflect that.

-Water weight--salt, check your labels. They usually measure it in milligrams (mg) on labels so try to keep that under 2000 mg. I don't have a better word for it, but salt makes you feel more "fluffy" because you retain more water in your tissues and blood with more salt.

-Awesome trick!!! try taking out soft drinks, or one salty/sweet/fatty snack a day and replace it with something healthy you really enjoy. Maybe it is strawberries with low fat yogurt, blueberries, wheat-thins, and many more. I've known people who lose 10 pounds alone by just doing this!!!

-use the rainbow rule. Today, did you eat something red? orange? yellow? green? blue? purple? white? brown?

Some links and sources of information:
Drug info: Really good! http://www.healthline.com/multumcontent/orlistat
Official Site: http://www.myalli.com/default.aspx
More drug info: http://www.webmd.com/drugs/drug-148551-Alli+Oral.aspx?drugid=148551&drugname=Alli+Oral

According to the FDA and Alli's Web site, Alli works by taking some of the fat in the foods you eat and making it so your body cannot digest and use it.

Therefore, you are getting fewer calories than you actually eat. So it can work.

However, you have to be careful that you eat a lower-fat diet as part of the plan. Also, you may need a vitamin supplement since you are absorbing less of the nutrients in your food, too.

I've also included a link below from a previous answer that I provided that goes into a lot of detail about Alli.

have not used the kind of diet pills you said, so the effect can not say how kind he was to give you the authority to recommend a product, meizitang botanical slimming capsule slimming product slimming professional, I've used, safe with no side effects, weight loss very important, safe and healthy weight loss is more important. Eat meizitang slimming capsule, fast weight loss in the basis, to supplement the body energy, healthy weight loss products. Here is the website about it: http://www.meizitang.us/ good luck!

Now a days their are so many excercise n medicine over their for weight loss.
but when you use Alli ,its very helpful in weightloss because Alli contains a drug called “Orlistat.” In really simple terms, orlistat absorbs the fat from foods you eat every day.