It is kind of difficult. Basically you have to read labels in order to get the correct information on calories and portion size, then weigh everything to that portion size. You'll be surprise at how small 100 calories is on some items....
You can enter your recipes and once you've done that, you will have the calories/serving saved, then you just enter that food and it enter the calories for you. I did it once, I can go back and figure out again if you like or you can ask your question on the Improve MedHelp Suggestions Forum via the following link:
http://www.medhelp.org/forums/Improve-MedHelp-Suggestions/show/110