[Dysphagia] amount of liquid in foods

[vbalmer at consolidated.net (Velvet Balmer)]

I know that the amount of liquid put into a food item does not remain  
constant once cooked, however how do you figure out how much remains  
in it?  For example, if you cook pudding, using 4 cups of milk, and  
then subsequently eat all of that pudding, how much liquid did you  
get out of what you ate (it wouldn't be 4 cups worth, would it?)  Or  
if you baked a pumpkin pie, how much of the original liquid from the  
pumpkin would remain?  What about jello -- is the gelatine emulsifier  
reducing the total of fluid contained in the final product?

Sorry if these are elementary questions, but I am in need of  
answers.  Is there some formula out there for determining the amount  
of liquid within a food source?

Thanks for your help,
Velvet