Despite the abundance of information on diet and exercise in the media, Americans are continuing to get fatter. According to a recent analysis, an estimated 30 percent of adults – over 60 million – are obese, defined as having a body mass index (BMI) of 30 or higher, and, an estimated 65 percent of adults are overweight or obese, defined as having a BMI of 25 or higher.
While increased food portion sizes, consumption of high-fat fast foods, and lack of exercise are the most common reasons cited for the overweight and obesity epidemic, another possible explanation is a hormone called cortisol.
Cortisol is produced in the adrenal glands in response to the secretion of adrenocorticotropic hormone (ACTH) in the pituitary. Metabolically, cortisol increases the concentration of blood glucose by converting amino acids into carbohydrates (gluconeogenesis), inhibiting glucose uptake, and breaking down lipid stores into adipose tissue (lipolysis).
Cortisol, Stress and Weight Gain
Cortisol is known as the “stress hormone” and is secreted in response to all forms of stress. These include environmental stress (heat, cold, and noise, etc.), psychological stress (worry, fear, etc.), chemical stress (pollution, drugs, etc.), biochemical stress (nutritional deficiencies, simple sugar consumption, etc.), and physical stress (overexertion, trauma, and infection, etc.).
During the “fight or flight” response, the adrenal glands secrete large quantities of adrenal cortical hormones. These hormones mobilize the body’s energy supplies and direct all of the body’s resources toward survival.
This response worked well when our primitive ancestors actually faced life threatening situations, but is not well suited for today’s modern world since most stressful situations do not require us to fight or run away.
The body’s response to modern stressful situations causes problems because although there’s no physical activity in response to the “threat,” cortisol signals the body to refuel as though there was. This signal to refuel, or increased appetite, leads to weight gain in the chronically stressed.
Ways To Reduce Cortisol
Exercise: Aerobic exercises such as running, roller blading, cycling and cross-country skiing increase the production of endorphins. Endorphins (“endogenous morphine”) interact with the opiate receptors in the brain to reduce the perception of pain much like the effect of morphine or codeine. Endorphins also produce an overall feeling of euphoria, commonly known as the “runners high,” in response to prolonged exercise. These chemicals counteract the harmful effects of stress by lowering cortisol levels.
Avoid overconsumption of simple carbohydrates: Eating simple carbohydrates without proteins or fats to slow down the absorption rate causes the body to generate a strong insulin response which can produce a dramatic drop in blood sugar several hours after the meal was eaten. A fall in blood sugar triggers the secretion of cortisol. This situation can be avoided by eating balanced meals which include proteins, fats and fiber along with carbohydrates.
Rest: Get enough sleep. Chronic sleep deprivation increases stress and makes weight gain more likely. Researchers have found that those between 32 and 59, who slept four hours or less per night, were 73 percent more likely to be obese than those who slept between seven and nine hours per night.
Practice stress reduction techniques: Techniques such as meditation, deep breathing, mindfulness, and yoga are effective methods of stress reduction.