Your brain is the commander-in-chief of your body. It constantly receives information from your internal and external environment and decides the best course of action to take for your survival. The brain carries out this action by sending messages through the nerves of the nervous system to the appropriate parts of the body.
For example, when the sympathetic nervous system is activated, it will help simultaneously change the behavior of the heart, lungs, eyes, brain, digestive system, adrenal glands, bladder, and skeletal muscles. All of this is done to achieve one goal - survival. On the other hand, the parasympathetic branch of the nervous system stimulates digestion, recovery, and rest throughout the organs of the body when we are not faced with a threat.
These two branches of the autonomic nervous system help us explain how our brain controls our body, but can our body control our brain?
You are the Sum of Your Neurobiology
In his book,
Incognito: The Secret Lives of the Brain, Neuroscientist David Eagleman explains:
...who you are depends on the sum total of your neurobiology."
Neurobiology is dictated by more than just the brain. Just like any government, even a dictatorship, the leader is influenced by other members of the governing body. Even though the brain can affect every organ in the body through the sympathetic and parasympathetic branches of the nervous system, the brain cannot veto the power of the gut.
Comment: There's a wealth of evidence that indicates that sugar causes major problems to human health. Whether it alone is the smoking gun in the epidemic of health problems that we're seeing today is hard to say, however it's clearly detrimental to health overall and is best avoided.