According to a spate of television ads, the latest villain in the battle of the bulge isn’t one of the usual suspects, like fast food, a sedentary lifestyle or the much-maligned “carb.” No, the culprit is a hormone called cortisol.
Cortisol is a hormone, produced by the adrenal gland when the body is under stress. Your hypothalamus, via the pituitary gland, directs the adrenal glands to secrete both cortisol and adrenaline. Cortisol is released as part of your daily hormonal cycle, but both hormones can also be released in reaction to perceived stress -- both physical and emotional – as part of the body’s fight-or-flight response that is essential for survival. Adrenaline makes you energetic and alert, and increases metabolism. It also helps fat cells to release energy. Cortisol helps your body become even more effective at producing glucose from proteins, and is designed to help quickly increase the body’s energy in times of stress.
It’s not the classic fight-or-flight stress that’s thought to cause weight problems, because in those situations, a stressful event is quickly resolved, and the cortisol released is absorbed into our systems, aided by the increased circulation provided by a pounding heart.
Instead, some experts now believe that the problem for many of us is being in a constant state of stress, for various reasons. This leads to a constant state of excess cortisol production. Excess cortisol stimulates glucose production. This excess glucose then typically is converted into fat, ending up as stored fat.
There are a number of research studies that have shown that fat cells can, in the presence of too much adrenaline, become resistant to the effects of adrenaline. Eventually, the fat cells become unresponsive to adrenal stimulation to release fat, but through the presence of high cortisol, they’re more responsive to fat storage. At the same time, high levels of circulating cortisol increase the risk of obesity and increased fat storage -- and particularly, abdominal obesity, one of the most dangerous types of obesity, and one that contributes to an increased risk of metabolic syndrome, diabetes, and heart disease.
Insulin Resistance and Metabolic Syndrome
One factor we know can cause imbalances in cortisol is overconsumption of simple carbohydrates. When you have eaten a concentration of simple carbohydrates – a snack of a candy bar and/or a soda, for example -- the body generates a strong insulin response, to prevent excess blood sugar. This large insulin response in turn can trigger a dramatic drop in blood sugar – sometimes to levels that are even too low – in the 3 to 5 hours after the simple carbohydrate was eaten. When blood glucose levels fall, this triggers a surge of adrenal stress hormones, including adrenaline and cortisol. (Sometimes, this can cause nervousness, anxiety, irritability and even palpitations. This is the phenomenon observed in some children when they’ve had “too much sugar.”)
The same up and down pattern of insulin, glucose and adrenal stress hormone levels either doesn’t happen at all, or is severely blunted, after eating a complex carbohydrate, proteins, fats, a balanced meal that includes fats, proteins, and fiber alongside the carbohydrates, because the processes of digestion and absorption are slowed down.
Over time, higher blood glucose levels can occur for a number of reasons:
- Consumption of too many carbohydrates, especially simple, refined carbohydrates
- Eating too many calories, so that excess calories are being stored as fat and then released as glucose
- Very high stress levels are stimulating cortisol production
- Other dysfunctions in the metabolic and hormonal systems
It is not as severe as diabetes, where the cells cannot secrete enough insulin to maintain safe blood sugar levels. Instead, insulin levels may actually be high, and the pancreas continues to pump out even more insulin in an attempt to store the glucose left in the blood. But the cells cannot react to the insulin that is released, and the glucose continues to circulate in the bloodstream. Then, when you eat, glucose levels rise even higher. After a few years, the overworked pancreas begins to tire, and may loose its ability to produce any insulin at all, leading to type 2 diabetes. Insulin resistance is, in fact, sometimes called pre-diabetes, because it often leads to type 2 diabetes.
The high levels of insulin circulating through the bloodstream also stimulate storage of fat and amino acids, and prevents breakdown of fat and protein. It also prevents release of glucagons.