As waistlines expand, so does the epidemic of metabolic syndrome. It’s estimated that nearly one of every four American adults has this condition(1). If you’re one of them, it puts you on the track to developing type 2 diabetes and triples your risk for heart disease down the road. The identification of metabolic syndrome two decades ago(2) is now recognized as a turning point in our understanding of how metabolism can go awry, resulting in obesity, diabetes and cardiovascular disease.
What Is Metabolic Syndrome?
Metabolic syndrome involves several conditions that predispose people to diabetes and heart disease. These include:
- Obesity, particularly excessive fat in the waist and tummy, giving an “apple-shaped” appearance
- High blood triglyceride levels, reflecting problems metabolizing carbohydrates
- Low HDL (“good”) cholesterol
- Higher levels of the small dense type of LDL particles, which can attach to artery walls and form plaque, although total LDL (”bad”) cholesterol is usually within normal range
- High blood pressure
- High-normal or elevated blood sugar
Additional markers include chronically elevated inflammation levels, such as C- reactive protein (CRP) and abnormal blood vessel function.
A person is defined as having metabolic syndrome if he or she has three or more of the following markers(3).
|Waist Circumference||≥ 40 inches||≥ 35 inches|
|Triglycerides||≥ 150 mg/dL*||≥ 150 mg/dL|
|HDL cholesterol||≤ 40 mg/dL||≤ 50 mg/dL|
|Blood pressure||≥ 130/85 mm Hg or use of medication for hypertension||≥ 130/85 mm Hg or use of medication for hypertension|
|Fasting glucose||≥ 100 mg/dL or use of medication for high blood glucose||≥ 100 mg/dL or use of medication for high blood glucose|
*Milligrams per deciliter.
What Causes Metabolic Syndrome?
The prevailing opinion is that all of these markers are signs of insulin resistance, meaning the diminished ability of a given amount of insulin to exert its normal effect. When insulin resistance develops, it can impact metabolic processes in many ways, resulting in the specific markers listed above. However, different individuals respond to insulin resistance in different ways. Also, the time frame in which certain signs develop varies. This variability makes defining—and treating—metabolic syndrome tricky.
Treating Metabolic Syndrome
How to treat metabolic syndrome is controversial. Because there are several potential markers, the public health community has struggled with the decision of how best to define, diagnose and treat it. Nutritional approaches have generally been downplayed in favor of multiple medications that target the individual markers. Conventional recommendations tend to emphasize caloric restriction and reduced fat intake, even though metabolic syndrome can best be described as carbohydrate intolerance. The most effective treatment for metabolic syndrome is to control the intake of carbs, not fat. In fact, restricting dietary fat and replacing it with carbohydrate actually makes many of the problems of metabolic syndrome worse. The metabolic syndrome paradigm has therefore caused a great deal of distress—and pushback—among those advocating low-fat diets. For more on how to prevent metabolic syndrome, see How to Reduce Your Risk for Metabolic Syndrome.
- Ford, E.S., Giles, W.H. and Dietz, W.H., “Prevalence of the Metabolic Syndrome among US Adults: Findings from the Third National Health and Nutrition Examination Survey,” The Journal of the American Medical Association 287 (2002), 356–359.
- Reaven, G.M., “Banting Lecture 1988: Role of Insulin Resistance in Human Disease,” Diabetes 37 (1988), 1595–1607.
- Grundy, S. M. Brewer, Jr., H. B., Cleeman, J. I., Smith, Jr., S.C., and Lenfant, C., “Definition of Metabolic Syndrome: Report of the National Heart, Lung, and Blood Institute/American Heart Association Conference on Scientific Issues Related to Definition,” Circulation 109 (2004), 433–438.