The answers aren't coming from the body (or the mind), it's coming from Universal Consciousness as expressed through our body. It's actually a non-local phenomenon -- the body is just an instrument. It is actually consciousness responding.
The answer may be influenced by the mind/body or the environment, i.e. distorted, but when done correctly it is 100% accurate. This has been shown in many studies where testers believe the opposite of what is true, but the correct answer still comes through.