The Flight or Fight Response - Stress And Weight Gain

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 continuous basis.

Here’s what we know so far:

1. Your body reacts to stress and prepares itself to run or fight by releasing certain hormones (adrenalin, cortisol, insulin).

2. Your brain cannot distinguish between chronic stress and a life-threatening situation, so it will react the same in both cases.

3. In today’s 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 you’ll never meet and the bills you can’t 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) that’s 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 body’s 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 McDonald’s (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 you’ll most likely hear an emphatic, “Yes!” So if we can’t eliminate stress, how can we combat the effects of the flight or fight response and stop making ourselves fat?

Exercise, Fat’s Triple Threat

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:

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 meditation.

Early Warning Signs of Stress