Measuring meats before or after cooking??

HealthyMom4MyKids

Hi. I am starting my new way of eating on Jan. 1 and I am making my menu for the week. I am married with 3 kids and I am trying to change our over all way of eating. I am going to attempt calorie counting, but am worried that it is going to be extremely hard with some foods. I am really going to focus on learing what a portion size is. Suppose I cook a roast, how much is a serving size for cooked meat? Any good portion control sites?

Thanks!

Kim