I need help with importing...

[nick-XxxX-kcin]

sorry if i sound like a noob but im new to this site. everytime i import models and save i go into the import manager and notice that the model size went down and it WE wont notice it any more... does anybody know how i can stop it from doing this? im importing them correctly and stuff too... (By the way the same thing happens with replaceable textures and the map preview.)