Well, I probably should start selling all the food I picked up :P
What is odd about the system is that items take up one weight regardless of how many you carry so if you carry one potato or 6546546 of them, it will just take one "weight" unit.
Oh, and is food really useless? I haven't really noticed any real benefit from eating.
Yes, that "Weight" system is indeed weird. You can even raise a skill that will increase your item carry capacity by 20...
Food increases your health regeneration, I thought it was useful the first couple of levels or so, but later on it is pretty much useless...