I used to take Xenical. From what I can remember, it is very important to limit fats because the Xenical aids the body in excreting the fat in your excrement. If you eat more fats than what your doctor or health professional is suggesting, your movements may be more oily or loose, I THINK. I haven't taken this drug in years but that is what I remember.
Again, this is from what I remember, not medical advice. I need to eat low fat too, so I suggest eating fruits and vegetables and foods that are grilled, not fried. Also I don't know if there are nutrition labels on your packaging that give the fat content listed but I would try to use your common sense, if you think a food is too fatty, perhaps eat a little or not at all. Also, don't hesitate to ask your health professional such as your doctor's office or whoever is prescribing this for you to give you advice. That is what they are there for, to help you!
I hope that you lose the weight that you want to lose, safely on Xenical. I lost some weight on it. I think what is important to remember with diet pills is that they are not a 'magic bullet.' It is still important to eat healthily and exercise.
Feel free to private message me if you like.