Hi, I got Xenical from my doctor last year (I think it is a slightly stronger, perscription version of Alli). There were some pretty unpleaseant side effects (namely orangey fatty liquid in the toilet-and the potential to have an accident, which made me quite paranoid) so I wouldn't advise being far from a toilet. I did seem to lose weight easier but I wonder if it is psychological as I found myself actively avoiding anything fatty to ensure I didn't see that horrible orangey by-product.
Sorry if that sounds really yucky but I hope you get the gist of it!