Smelly Orange Oily Stool?

I read other posts and I guess it has to do with eating fatty foods and Olean/Olestra? My neice recently ate fat free lays and pringles. It said that those may have been a problem because it has Olean in them. But also, she's taking this diet pill Alli? I guess my sister read in the pamphlet that came with it that it may result in a reddish/orange stool. I talked it over the phone with my sister about it, and I really wanted to take her to the hospital, but she said it was either from the pill or just fatty foods with olean and olestra. She rarely eats chips now, but she did 2 days ago and yesterday. Any other reasons why this may be occuring?