If I create a custom food, and enter the same exact nutritional information as one that I've browsed for, the calories from fat is not the same.
I've checked to make sure that my custom food is EXACTLY the same for the entered information, and it always is.
Example: I create a custom food for Banana, the FitDay "Calories from fat" is listed as 3.3, whereas my custom Banana comes out to be 3.5.
This is no big thing, I just wanted to point this out. I'm assuming that the difference is due to rounding off at the custom level.