The Flight or Fight Response
- Stress And Weight GainBy Michael Stefano -
eDiets - The online diet, fitness, and healthy living resource
Millions of years ago, our cavemen
ancestors needed to react swiftly to any perceived threat. This flight or
fight response was designed to provide quick energy for 5-10 minutes,
enabling our forefathers and mothers to either do battle or run. At the first
sign of a dangerous situation, the human brain releases a substance known as,
corticotropin-releasing-hormone, or CRH. CRH travels to the adrenal cortex and
stimulates the release of the hormones adrenalin and cortisol.
This added adrenalin improves eyesight and
hearing, while lung capacity jumps and thinking becomes more focused. The
digestive system is temporarily shut down, and blood is shunted from the
internal organs for emergency use elsewhere. Heart rate and blood pressure
climb, and due to the increased cortisol levels, more stored fuel (fat and
glucose) is mobilized for quick action. Production of insulin, the fat storage
hormone, is also dramatically increased. Insulin overrides signals from
adrenalin to burn fat, and instead, encourages the body to store fat (for
future use) in the abdominal region.
This life-saving, emergency response plan was
appropriate to an era when surviving the day was the biggest concern. But when
was the last time you reacted to a stressful situation by actually fighting or
running away? The human brain cannot distinguish between a valid physical
threat and ordinary, day-to-day stress (also known as chronic stress). For many
stressed-out people, the flight or fight response is triggered on an almost
Heres what we know so far:
1. Your body reacts to stress and prepares
itself to run or fight by releasing certain hormones (adrenalin, cortisol,
2. Your brain cannot distinguish between
chronic stress and a life-threatening situation, so it will react the same in
3. In todays world, physical threats
are few and far between, but day-to-day stress is chronic, and can also trigger
the flight or fight response.
Cortisol is the Culprit
As you sit in your car and stew over the
wall of traffic in front of you, the deadlines at work youll never meet
and the bills you cant pay, your brain begins to sense the onset of a
threatening situation -- and sets the flight or fight response into motion.
You feel this as nervous tension or just
plain anxiety. Your heart pounds and you want to jump out of your skin, but you
can only sit. All that extra fuel (in the form of fat and glucose) thats
designed to provide you with emergency energy, is now being mobilized for
action. This energy goes unused and is left behind, only to be re-deposited as
fat -- and to make matters worse, usually as belly-fat.
High cortisol levels are associated with
increased appetite and increased fat deposits, typically around the trunk and
abdomen. Some researches theorize that this unused fuel (or fat) is generally
deposited in the abdominal area because of its proximity to the liver (where it
can be quickly converted to a usable form of energy).
As part of the bodys short-term
protective measures, cortisol, which was secreted along with adrenalin, acts
like the "adrenalin antidote." Upon removal of the stressful stimulus,
adrenalin levels quickly dissipate, but cortisol levels remain high, causing
insulin production to surge as well.
In the face of prolonged or chronic stress,
cortisol levels can remain constantly high, keeping you in a state of perpetual
hunger. We can easily see how elevated cortisol levels can promote weight gain
due to an overabundance of insulin. Insulin resistance, which affects 25
percent of all Americans, is also a risk factor for type 2 diabetes.
The average caveman was well served by a
system that signaled him to eat after every emergency, and where total energy
expenditure was not uncommon. Thankfully, today, true physical emergencies are
rare. But, this short-term protective system, although somewhat outdated, still
works. And to help short circuit the process even further, nowadays the act of
going out and obtaining food burns only as few calories as it takes to drive to
the nearest McDonalds (about one French fry worth), as compared to our
ancestors who had to hunt for every meal.
The stress response is hardwired into the
fabric of our lives. Ask the average man or woman off the street if he or she
gets stressed out on a regular basis, and youll most likely
hear an emphatic, Yes! So if we cant eliminate stress, how
can we combat the effects of the flight or fight response and stop making
Exercise, Fats Triple
One of the most obvious ways to combat fat
and the ravages of stress is with exercise. Exercise represents a triple threat
to body fat. First, exercise burns calories and utilizes stored body fat as
fuel. Second, working out increases the amount of lean muscle mass your body
must provide with fuel 24 hours a day. More muscle means less fat.
Research from Yale University has now
clearly demonstrated a third mechanism by which exercise reduces stores of body
fat, especially around the belly. Moderate to vigorous exercise, such as
lifting weights, can offset the negative effects of cortisol and insulin. With
as little as 10 minutes of strenuous exercise, the brain begins to produce
beta-endorphins that calm you down and decrease levels of the stress hormone.
Many feel that strenuous exercise actually mimics a typical caveman-like
physical reaction to a threat. This makes exercise the modern-day version of an
appropriate reaction to the flight or fight response.
A note of caution:
- Dont overdo it. Too much
exercise can actually cause additional stress and associated symptoms.
- Be sure to get plenty of rest.
Inadequate sleep increases cortisol levels and reduces leptin, a hormone that
- Avoid dieting. High protein, low
carbohydrate diets do not provide enough energy during stressful situations.
Common sense dictates that you eat right,
get plenty of sleep and exercise, but now we have another weapon in the battle
of the bulge. Stress management, whether through, education, exercise, therapy,
or just plain fun is a necessary ingredient in fitness and weight loss, as it
is in a healthy, well-balanced life. Be sure not to ignore the signs of being
overstressed, of which being overweight is just one symptom. Recognize symptoms
and do something today! Take control of your life, whether with exercise or
other types of stress management techniques, such as psychotherapy or
Early Warning Signs of Stress
- Sudden weight loss or weight gain
- Excessive fatigue, tired but
cant sleep, lack of coordination
- Speech difficulties, impatience
- Chest pains, headaches
- Low or high blood sugar
- Low or high blood pressure
- High cholesterol or triglycerides
- Repeated colds or flu, hair loss
- Muscle aches, lower back, shoulder
and neck pain
- Ulcers and gastric disturbances
- Nail biting, teeth grinding
- Menstrual problems
- Withdrawal from social life,
A frequent contributor to eDiets,
Michael Stefano is the best-selling author of the enormously popular book,The