Calories change when cooking food?

Why do some (all?) foods change their calories depending on how you cook them? For example, an egg scrambled vs. hard boiled vs. omelet vs. raw -  all have different calories.

It's not strictly true.... CC assumes that your omelette or poached eggs has been cooked in some oil and that your scrambled eggs have had the traditional butter and cream added as you'd find on a hotel menu.  However, if you use a smear of oil in a non-stick pan for your omelette, poach your eggs straight into the water and let your scrambled eggs down with a little skimmed milk you'll find the calorie count is very nearly the same as the raw eggs you started out with.....

Wow.. That means I have been overcounting sometimes... interesting.  Thanks.

As a general rule with CC's database, if you are cooking something from scratch enter the ingredients in their raw state by weight.  If you make scrambled eggs, as I do, with 2 large eggs (70 cals each) and 1 floz of semi-skimmed milk (15 cals), then that's what you enter.    If you are purchasing something outside the home (like scrambled eggs in a cafe where you don't know what they contain) use the cooked version.

Thanks for the tip!  it makes so much sense now.