I think you may be confused about how decomposition works. In order to help you understand this process, I'd like you to do a little experiment with me. Are you ready? Okay.
First, kill yourself.
Now, look in the mirror. Are your lips rotted completely off? Do you have yellow pus seeping out of your eye sockets? Are you missing the lower half of your body?
No. You still look pretty normal, right?
Ok, now let yourself rot for a week and look again.
Are your guts pouring out of your stomach yet? Or are you just looking a little pale? If you happen to be a handsome young Englishman with excellent bone structure, perhaps you look a little like Nicholas Hoult in the upcoming satirical zombie drama, "Warm Bodies". Lucky you!
Okay, now continue to rot for about a month. Your hair should be starting to fall out by now and you probably have some nasty stuff happening on your skin. Are you starting to look a little more like a "REAL" zombie now? Good! You just demonstrated some of the different stages of human decomposition. It's a shame you aren't imbued with the unknown mystical forces that cause a corpse to rise up and continue living as a fictional undead creature, because then maybe you'd be a little better preserved and possibly even handsome. But oh well! At least you learned something.