Stress is a psychological and physiological response to events that upset our sense of balance. The stress response ("fight or flight") was intended to protect us from physical threat. Heart rate and blood flow to large muscles increase to allow us to run faster or fight harder, blood vessels under the skin constrict to reduce bleeding in case of injury, pupils dilate to allow us to see better, blood sugar increases rapidly to provide an energy boost and speed up reactions, and body processes not related to immediate survival are suppressed such as memory, digestion, growth hormones and the immune system. These changes are in response to the release of the stress hormones norepinephrine, epinephrine (adrenaline), and cortisol. When an individual perceives a challenge to his control of a situation, norepinephrine the "fight" hormone is released. Epinephrine, the flight or anxiety hormone, is released if the perception continues and the individual feels a possible loss of control. When the stress is prolonged the individual feels defeated and hopeless which results in the release of cortisol.

Energy production and metabolism are regulated by cortisol. Normal levels of cortisol are highest in the morning and are associated with awakening. Chronically elevated levels of cortisol can impair the normal sleep cycle and cause difficulty sleeping. Cortisol mobilizes energy by moving fat stores (in the form of triglycerides) from subcutaneous sites to sites deep within the abdomen known as visceral fat. Increased levels of cortisol have been associated with increased appetite, craving for fat and sugar, and weight gain. Prolonged elevations in cortisol are thought to contribute to obesity by increasing abdominal fat and stimulating appetite.

Modern-day stress is usually in response to psychological rather than physical threat. Psychological stress often results from situations that are long term rather than immediate, such as caring for an ill parent or financial pressures from falling behind in your bills. Psychological stress is not helped by the fight or flight response but the response to it is the same. When our stress response is activated so often that our bodies do not have time to return to normal, we are in a state of chronic stress.

Chronic stress can cause prolonged periods of higher levels of stress hormones, especially cortisol, which may have a number of negative effects. Some of these effects are impaired memory and cognitive function, suppressed thyroid function, increased blood sugar, decreased bone density, decreased muscle mass, higher blood pressure, lowered immunity, and increased deposit of abdominal fat. Consequently, stress may be a contributing factor in dementia, hypothyroidism, type 2 diabetes, osteoporosis, high blood pressure, increased susceptibility to infection, and heart disease.

Stress will always be a part of daily living. In fact, stress provides challenges necessary for normal physical and psychological development. However, too much stress over long periods of time combined can lead to hormonal imbalances that cause physical and chemical changes that can cause disease and ultimately death if left unchecked. A regular exercise and stress management program are keys to reducing stress-related obesity and the health risks associated with it. Effective stress management includes identifying and avoiding stressors when possible, learning to use relaxation techniques such as progressive relaxation and deep breathing in response to stress, eating a healthy diet, and getting enough rest.

References: http://www.helpguide.org/mental/stress_signs.htm, http://www.unm.edu/~lkravitz/Article%20folder/stresscortisol.html.

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