Cortisol and Syndrome X
Most people have never even heard of syndrome X (also termed metabolic syndrome), which refers to a cluster of related conditions and symptoms including diabetes, insulin resistance, obesity, hypertension, high cholesterol, and heart disease (yikes!). If you are starting to gain weight, feeling low on energy, seeing your cholesterol level and blood pressure creep up, and feeling as if your mind is not quite as sharp as it used to be, you are a likely candidate for developing (or you are already suffering from) syndrome X.
One of the key metabolic aspects of syndrome X is insulin resistance (discussed in the previous section as it relates to obesity). Insulin resistance leads to a reduction in the body's cellular response to insulin, which interferes with blood-sugar regulation, increases appetite, and blocks the body's ability to burn fat. When insulin resistance is combined with a poor diet (high in fat and/or refined carbohydrates), the result is the metabolic syndrome known as syndrome X, which can have an impact on virtually every disease-inducing process in the body.
Some authors have proposed that both insulin resistance itself and syndrome X are caused by a diet high in refined carbohydrates such as cookies, soft drinks, pasta, cereals, muffins, breads, rolls, and the like. While it is indeed true that refined carbohydrates (also known as high-glycemic-index carbohydrates) can raise blood levels of glucose and insulin, it is highly speculative that these junk foods actually cause syndrome X. (There's no controversy, however, that a diet high in such foods will certainly not help your health.) Instead, it is far more likely that the metabolic cascade of events set in motion by stress and elevated cortisol levels is the primary factor in getting a person started toward developing full-blown syndrome X—and a poor diet may hasten the trip.
People at highest risk for syndrome X are typically those of us who are approaching "middle age" (which is always a relative term). Aside from the fact that syndrome X simply leaves you feeling kind of "blah" (fatigued, fuzzy-headed, depressed, and disinterested in sex), it also sets the stage for several life-threatening conditions such as obesity, heart disease, diabetes, Alzheimer's disease, and some forms of cancer.
Among the early signs of syndrome X are low energy levels and "fuzzy" mental functioning. Very often, these feelings strike following meals, due to the body's difficulty handling carbohydrates. A syndrome X sufferer will also notice that his clothes begin to fit a bit tighter due to a gradual weight gain of a pound or so at a time. Most problematically, the person will also have trouble losing those extra few pounds due to a variety of metabolic changes such as elevated blood sugar, increased insulin levels, and reduced levels of certain anabolic hormones (all of which you remember from the previous section about how stress makes us fat).
Taken separately, each of these relatively mild changes in one's metabolic machinery is not a big deal and is likely to be brushed off by the sufferer or his health-care provider with an overly simplistic recommendation to "get more exercise" or "watch what you eat." When considered together, however, the additive effect of each of these metabolic changes compounds a person's overall risk of serious health problems.
The primary effects of stress in raising one's risk of diabetes (only one aspect of syndrome X) are related to chronically elevated levels of glucose and insulin in the blood. Over time, elevated glucose and insulin cause the body's cells (primarily the ones in fat and muscle tissue) to become less sensitive to the effects of insulin, a condition known as insulin resistance. In response to the development of insulin resistance in these cells, the body begins to produce even more insulin—starting the vicious cycle that leads to development of full-blown diabetes.
Insulin resistance is perhaps one of the earliest metabolic events leading to full-blown syndrome X—and insulin resistance is certainly exacerbated by, if not exactly caused by, a diet high in refined carbohydrates (sugars) and by elevated cortisol levels (from chronic stress). Refined carbohydrates increase glucose and insulin levels in the blood, while cortisol reduces the effectiveness of insulin and reduces the body's ability to burn fat for energy. Both diet and exercise can play important roles in helping to control blood-sugar and insulin levels, but unless you adequately control cortisol levels, your attention to diet and exercise will leave you spinning your wheels.
Adding to the complexity of the connection between stress, cortisol, and metabolic alterations (e.g., insulin resistance), is the recent finding that inadequate sleep may actually causecontribute to insulin resistance. This is particularly interesting because of the well-known link between sleep deprivation and elevated cortisol levels. In 2001, at the Annual Scientific Meeting of the American Diabetes Association, sleep researchers from the University of Chicago presented new evidence that inadequate sleep may promote the development of insulin resistance. The research team compared "normal" sleepers (averaging 7.5 to 8.5 hours of sleep per night) to "short" sleepers (averaging less than 6.5 hours of sleep per night), finding that the short sleepers secreted 50 percent more insulin and were 40 percent less sensitive to the effects of insulin compared to the normal sleepers. This is precisely the same effect seen during the aging process, when we begin to sleep fewer hours per night, our cortisol levels begin to rise, and our cells begin to become resistant to the effects of insulin.
Could inadequate amounts of sleep also be contributing to premature aging? Probably. The Chicago sleep researchers also suggested that sleep deprivation, which is becoming commonplace in industrialized countries, may play a significant role in the current epidemic of obesity and type-2 diabetes. A recent poll conducted by the National Sleep Foundation documents a steady decline in the number of hours Americans sleep each night. In 1910, the average American slept a whopping nine hours per night; in 1975, it was down to only about seven and a half hours; and today we average only about seven hours a night—and many of us get far less than that.