Last time we took a look at the acute
stress response and how it can benefit us during life-threatening situations
(man running from a bear): hormones are released which cause an increase in
heart rate and blood pressure, stored glucose is activated to provide an energy
source to the "exercising" muscles and so on. Once the threat has passed, the body will return to a state which makes
us feel like we have just been pulled off of the ceiling, therefore we can continue
on with the business of daily living.
Now let's look at what happens when we can't turn off the stress
response and it moves from being acute to chronic (sustained).
Close your eyes for a moment and imagine
you are stuck in rush hour traffic and it is going to make you late for the big
meeting, or you are about to take the most important certification exam and if
passed, will earn you a job promotion.
How does your body react to these scenarios? I bet if you think about times when you may
have been faced with these same situations, your body responds the same way as if
you are running for your life. Why? Because it cannot distinguish the difference
between acute and chronic stress. The effects
of chronic stress on the body is such a broad topic that it is impossible to
cover everything in one post. Today, we
are going to take a look at the how and why chronic stress is linked to Type 2 diabetes. This will provide an example of how stress
serves not as our friend, but rather as a foe.
The work of Robert Sapolsky (PhD),
Professor of Neurology and Neurosurgery at Stanford University, provides
insight into the fascinating connection between stress and chronic disease
(2010). Dr. Sapolsky tells us that when
we are faced with intermittent stressors every day (rush hour traffic, annoying
co-worker, etc.) and allow this to affect us psychologically, then the stress
response never shuts off (2010). So how is this linked to diabetes? Let's take a look. The foods that we eat (carbs, proteins, and
fats) are broken down and the nutrients are absorbed to sustain life. Anything
that is not immediately used is stored in fat cells and the liver for future
energy needs. We are going to focus on
our primary energy source which is glucose.
Foods such as pasta, bread, vegetables,
cookies, and cakes are all contain carbohydrates which are broken down rapidly
into simple sugars (glucose) which provide energy for cell metabolism and
muscle activation. The hormone insulin allows
these sugars to move from the bloodstream into the cells to accomplish this
task. However, when the body is faced
with stress, the brain sends signals to the pancreas to stop releasing insulin. The reason why is that at a time when we are
running from the bear, we do not need to store glucose, but rather need every
bit that is released from the cells and liver to provide energy to our moving
legs and arms. When we are under chronic
stress the same thing happens: the release of insulin is shut off. Sapolsky notes that we face intermittent
stressors throughout the day which turn on and off the stress response. As a result, the body's metabolism is using
and storing energy in a haphazard way because it thinks the bear is chasing us
again (2010). Our body prefers to be in
a state of balance and if subjected to this roller coaster ride, eventually
something is going to give.
As we have seen previously, when the body
is under stress it draws glucose from the liver and fat cells to provide extra
energy for the muscles. Once the threat
is over, the brain says "Hey, you need to replace all that glucose you
just used up so eat more carbs." Our
hunter-gather ancestors did this exactly and their bodies stored the glucose
for future needs. The one thing about
them was that they were always on the move looking for their next meal and
fending off threats. They consistently
met their metabolic needs in this way.
Remember, they faced more acute than chronic stress situations than we
do today.
Enter us, the chronically stressed,
westernized society. If you have not
guessed it by now, our body is going to think we are constantly running from
bears and use up the glucose stores.
What happens next: our brain tells us we need carbs to replace our
energy stores. We do this by eating
refined foods such as white breads and pastas, and fast foods versus the whole
foods (another discussion) that our ancestors consumed. Under normal circumstances we store excess
nutrients in the fat cells until needed.
Because our stress is chronic, we will have a tendency to overeat (and
gain weight) to replace the "expended glucose" and here is where it
becomes our foe.
By nature, we are a more sedentary society
and therefore our metabolism is not as efficient in the use of our energy
stores. Eventually, the fat cells become
too full and cannot store anything else.
The brain tells these cells to resist insulin which in turn leads to
excess glucose in the body known as hyperglycemia. Sustained insulin resistance leading to
hyperglycemia is known as Type 2 Diabetes.
This is a very preventable condition that requires providing the body
with appropriate nutrition, exercise, and stress management/coping skills. Thus
begins our journey on the road to wellness.
Until next time, be well.
Tim
References
Sapolsky, R. (2010). Stress and Your Body. Virginia: The
Great Courses.
