I'm not trying to be funny... but if oil doesn't evaporate, then why do I get a fine layer of grease on my range hood after lots of use of my deep fryer?

It's my understanding that all liquids have a boiling point at which they turn to a vapor (or gas).

So how do you figure how much oil is absorbed and how much floats away in the air?

Maybe such a small amount is lost that it's insignificant and measuring the leftover oil is the appropriate way.

Can you enter the food on fitday and select the method of cooking as "fried"?
Many foods have this option.

How important is it that you get an exact measurement of your fat grams?
Do you want to know down to the last teaspoon, or are you trying to make sure you are getting a good fat to carb ratio?

Just some food for thought.

Did someone say food? YUM!