What they looked at was comparing folks who already like spicy foods and those who don’t usually eat it. What they found is that the cayenne pepper appetite suppressant properties are more pronounced for those folks who don’t normally eat spicy food. This sounds like good news for you if you don’t normally eat this kind of stuff. On the other hand, if you love salsa at hot sauce as much as I do, then this can come as quite a blow. Of course, the effect is quite modest in the first place so I think I’ll just go ahead and enjoy all my favorite spicy foods without worrying about it too much.
A couple of other things to note was that only a small quantity of pepper was required to get the benefit. The researchers added only half a teaspoon of cayenne pepper to tomato soup. Also, adding cayenne pepper to food was more effective than using cayenne pepper pills.
The article is an interesting read and covers some other foods as well, so you might want to head on over to the New York Times to read it.