Yeah, I didn't mean "therefore we should make everyone morbidly obese to raise the general intelligence level", I mean that having obesity indicates you have enough food (since too much food hasn't really been that widespread a problem before this).
Hmm. Whenever someone mentions that undernourishment is bad, people take that to mean that obesity is good, and vice versa. Is the obvious fact that the relationship between body weight and health needn't be monotonic not really that obvious, or is the topic of body weight just another mind-killer?
This is interesting, I wonder if there's anything to it: International variation in IQ – the role of parasites (paper) by Christopher Hassall of U. Carleton.
It strikes me as the sort of thing that could be as big an issue as lead in the environment. Raise the sanity waterline: improve health!