If you read a basic 100-level nutrition textbook, I guarantee you that you'll recant your statement. The problem isn't that the disciplines are disconnected from reality, but that people are treating bleeding-edge research as if it's scientific fact, rather than taking it all with a grain of salt as you would do in another scientific discipline.
What makes you think I haven't read such a textbook? The problem is the insights in economics are either obvious or dubious, save Ricardo's Law of Comparative Advantage. Which, I should add, doesn't seem to hold up in practice either.
