Chitosan is produced commercially by deacetilation of chitin, which is the structural element in the exoskeleton of crustaceans - lobsters, crabs, shrimp, etc.

• Chitosan is used primarily as a plant growth enhancer, and as a substance that boosts the ability of plants to defend against fungal infections. He has low potential of toxicity and is not expected to harm people, pets or wildlife.
• Chitosan can also be used in water processing engineering as a part of a filtration process. Chitosan causes the fine sediment particles to bind together and is subsequently removed with the sediment during sand filtration. Chitosan also removes phosphorus, heavy minerals, and oils from the water.
• Chitosan's properties allow it to rapidly clot blood, and have recently gained approval in the USA for use in bandages. The bandages include a layer of carefully produced Chitosan that, when applied to a wound, causes rapid clotting, stopping the bleeding. Chitosan is hypoallergenic, and has natural anti-bacterial properties, further supporting its use in field bandages.

Chitosan was discovered in 1811 and since than scientists are studying its properties and especially it's natural ability as "fat attractor". Chitosan is frequently sold in tablet form at health stores as a Fat Blocker It's popular to think of Chitosan as it have the capability of absorbing fat from the digestive system and expelling it from the body, thus users can lose weight without eating less.

Products based on Chitosan are commonly promoted as proven, safe, and natural weight loss products. They are relating to Chitosan some other side effects as reducing of cholesterol levels, fat neutralizing and all that with minimal or no side effects at all.

Interesting fact is that all those are just assumptions because up to date there is only one well-designed study published about the effects of Chitosan on humans. Results of the research confirmed that there is no evidence  to confirm any of the claims made by Chitosan promoters.

More than that latest research suggests that these claims are likely without any substance. At best, unmodified Chitosan would remove roughly 30 calories per day from a person's diet. Modified Chitosan is claimed to absorb anywhere up to three to six times its weight in fat and oils. Detractors claim that using Chitosan may have the deleterious effect of rendering ineffective certain minerals found in foodstuffs and required by the body in order to remain healthy.

This claim is not proven scientifically too. Other scientific research has indicated that using Chitosan can lead to vitamin and mineral depletion. It may cause to interference with the body’s natural ability to absorb fat-soluble nutrients, including vitamin A and D, and certain phytochemicals. As these nutrients are essential to the normal function and well being of all body processes, a nutrient depletion can have crucial consequences.

Chitosan has been proven as effective at lowering cholesterol levels but there are more safe and effective ways to achieve the goal. Human clinical trials did not prove Chitosan as safe and effective weight loss product too.

Alli ( OTC form of Xenical / Orlistat ):

Alli  ( Xenical ) was the first weight loss product to be approved to sale as non prescription weight loss product by U.S. Food & Drug Administration at 23.1.2006.

Alli is also known as Xenical, or Generic drug Orlistat or Tetrapydolipstatin.

Xenical is a weight-loss aid used to help people who fit certain weight and height requirements, lose weight and then maintain their weight. It comes in dark-blue, hard-gelatin capsules, with light-blue imprinting. Xenical is the first of a new class of anti-obesity drugs known as lipase inhibitors.

Fat we eat it broken down by enzymes called lipases so that our body can absorbed it. Xenical interferes with the activity of these enzymes temporarily, which blocks some of the fat you eat from being absorbed. This allows about 30% of the fat eaten to pass through the body undigested.

Xenical works only in the digestive system. It does NOT change your appetite. It blocks absorption of dietary fat into the bloodstream, by reducing the number of calorie intake from a meal.  Usually it cuts fat absorption by almost one-third. In combination with a low-calorie diet, it is used to promote weight loss and prevent the return of undesired pounds.

The recommended daily dosage of Xenical and Orlistat is 120mg taken three times per day; however Alli will be available in 60mg capsules only.

Clinical studies have indicated that Xenical and Orlistat can be effective as weight loss products whilst study participants have took the drug. Excessive pounds came back after discontinuing usage of the drug.

Xenical as non selective fat blocker which prevents absorbtion of fats and thus decrease also absorbtion of some essential fat-soluble vitamins too - beta carotene and vitamins A, D, E and K.

To compensate, you have take beta-carotene and a multivitamin with vitamins A, E, D and K once a day, at least 2 hours before or 2 hours after taking Xenical.

When you go out off your diet you  may suffer from some side effects. The more fat you eat, the more side effects you'll suffer. You have to keep to your recommended diet of meals containing no more than 30% fat.

Xenical use may cause to many side effects and some of them are very unpleasant:

• Abdominal discomfort or pain
• Anxiety
• Arthritis
• Back pain
• Fatigue
• Fatty or oily stools - 20% of patients
• Fecal urgency or incontinence - 22.1% of patients
• Flu
• Gas with fecal discharge
• generally mild and goes away - 23.9% of patients
• Increased defecation
• Incontinence (fecal) - 7.7% of patients
• leaky stools in some patients temporarily
• Menstrual problems
• Rectal discomfort or pain
• Sleep problems
• Stomach cramps
• Urgency to have a bowel movement
• Urinary tract infections
• Vaginal inflammation
• Vomiting

Recent animal studies show to a possible connection between Orlistat and an early sign of colon cancer.