Depends on cooking methods - generally i prefer methods where everything is controlled... i.e. dry frying, hot pots, etc. How I would calculate my beef stats:
Weigh 1kg of beef Find stats for 100g raw beef, multiply up so its for 1kg for total stats for the whole bit of meat. Cook beef Divide beef up into 5 portions Divide the uncooked total stats by 5 Thats it.
When you add in other stuffs like oil things change however.