It is very effective - many of my clients use it, but must be used corectly, coupled with an approprite diet, otherwise it will not work and will give side effects.
Guys, correct me if I'm wrong, but from what I remember when that stuff was being advertised all the time, there is nothing in it that promotes fat loss. It's just kills the apetite?
Heres how it works - forgive my smart arse again!!
Xenical aka orlistst is a pancreatic lipase inhibitor, ie it reduces the activity of the digestive enzyme lipase which breaks down emulsified fat to fatty acids and glycerol. hence less can be absorbed. if there is too much fat in the gut though you will get emulsification ++ = steatorrheoa (fat malabsorption) and fatty stool, with very bad guts!!
This is a very simple aetiological explanation - there is more to it than this.
People who use it would be losing weight anyway, but it just speeds it up. In the UK it is prescribable under certain criteria - quite strict - I am a State registered Dietitian (hence SRD!) and I work with Drs with obese patients. The evidence is overwhelming both epidemiologically and anecdotally.
Its pretty much en vogue here at the moment (in the USA too???) and the governemnt has set up protocols - see www.nice.org.uk the official website - they will have a link to Orlistst guidlines
PLease if you use it (the black markets full of it), use it correctly!