Xenical is drug that stops you body from metabolising dietary fat and oils, hence when you go to the toilet, whatever fat and oil you put in comes right out again. As I understand it Zenical is generally prescribed by doctors for grossly obese people after discussion of a range of safer and more sanitary weight loss options. You can find out about the drug at http://www.rxlist.com/xenical-drug.htm

Like all medicines and drugs you should talk to a registered medical practitioner before using them. I don't know if you need a prescription to buy this drug in Qatar.

Note I am not a doctor and you should seek medical advice.