Unlike most weight loss medications, Xenical works by reducing the amount of fat that is broken down in the stomach and absorbed into the body - typically by about 30%.

The active ingredient in Xenical, Orlistat, works to expel fats in the faeces. Given that fats have over twice the calories per gram of protein and carbs, this can make quite a difference to your total calorie intake.

Xenical is usually only prescribed to obese people with a body mass index in excess of 30kg/m?, so you should talk to your doctor before considering taking this drug.

It is also worth being aware of some of the side effects. These include uncontrollable rectal discharges, overall loss of bowel control, diarrhea, rectal pain and bleeding, liver inflammation and fatigue.

There are other issues to consider, including:

Using this drug may reduce the absorption of fat-soluble vitamins (A,D,E,K). You thus need to ensure that your diet is rich in fruit and vegetables. Indeed, many times your doctor will also recommend a multivitamin supplement.
The diuretic effects of this medication can reduce the effectiveness of oral contraceptive pills
This drug has not been tested on those under 12, on the elderly, or on those with impaired liver or kidney function.