Ghanimede, the above posters are correct, but did not fully answer your concern. Let me try to alleviate it.
The requirement to feed companions (pets/thralls) was removed a few updates back. Companions no longer die if not fed. Instead, they will disappear if you do not log in for a period of time, as determined in your server settings. You can view that through the settings menu.
The feeding mechanism is now a buff. If you feed a companion an item on their preferred list, they get a +25% offensive buff for a period of time. If you feed them an item not on their list, they receive a 10% offensive buff. The food is (for the most part) immediately consumed and that is why it seems as if the food disappears.
Once in combat, look at their health bar. Above and on the left, you will see a raised fist that denotes that buff. Someone here knows how long that lasts, I do not, sorry.
So, the devs replaced a stick with a carrot. No longer is it a penalty, but a benefit. You experienced the side effect of that benefit. Giving food for a companion to carry appears to destroy it, but is actually being used to help defend you.
So, as to your problem, there are new rules. Never try to get a companion to carry your food, but use him for the heavier stuff, rock, iron, wood, foundations, etc. Be aware of the food your companion will eat since it varies. There are herbivores in the game now. The way to test it is give him one piece and see if it sticks or disappears. Over a short period of time you will find out which companions will carry what type of food without eating it.
Regards, and best of game