What Is Metabolic Syndrome?

Medically Reviewed by Michael Dansinger, MD on February 13, 2024
3 min read

Metabolic syndrome is a health condition that everyone's talking about.

Although the first formal definition of metabolic syndrome entered medical textbooks not so long ago (1998), it is as widespread as pimples and the common cold. According to the American Heart Association, 47 million Americans have it. That's almost a staggering 1 out of every 6 people. The syndrome runs in families and is more common among African-American, Hispanic, Asian, and Native American people. The risk of developing metabolic syndrome increases as you age.

Indeed, metabolic syndrome seems to be a condition that many people have, but no one knows very much about. It's also debated by the experts -- not all doctors agree that metabolic syndrome should be viewed as a distinct condition.

So what is this mysterious syndrome, which also goes by the name “insulin resistance syndrome” or the scary-sounding name "syndrome X," and should you be worried about it?

Metabolic syndrome is not a disease in itself. Instead, it's a group of risk factors -- high blood pressure, high blood sugar, unhealthy cholesterol levels, and abdominal fat.

Specifically, metabolic syndrome can lead to a buildup of plaque in the arteries, known as atherosclerosis. This is when fats, cholesterol, and other substances stick to the sides of the arteries. The arteries then become clogged and brittle. Blood clots form when the artery walls are damaged. A clot can cause a heart attack or stroke.

Obviously, having any one of these risk factors isn't good. But when they're combined, they set the stage for serious problems. These risk factors double your risk of blood vessel and heart disease, which can lead to heart attacks and strokes. They increase your risk of diabetes by five times.

The good news is that metabolic syndrome can be controlled, largely with changes to your lifestyle.

According to the American Heart Association and the National Heart, Lung, and Blood Institute, there are five risk factors that make up metabolic syndrome.

Large Waist Size

For men: 40 inches or larger
For women: 35 inches or larger

Cholesterol: High Triglycerides


150 mg/dL or higher


Using a cholesterol medicine

Cholesterol: Low Good Cholesterol (HDL)


For men: Less than 40 mg/dL
For women: Less than 50 mg/dL


Using a cholesterol medicine

High Blood Pressure


Having blood pressure of 130/85 or greater


Using a high blood pressure medicine

Blood Sugar: High Fasting Glucose Level 

100 mg/dL or higher

To be diagnosed with metabolic syndrome, you would have at least three of these risk factors.

Experts aren't sure why metabolic syndrome develops. It's a collection of risk factors, not a single disease. So it probably has many causes. Some risk factors are:

  • Insulin resistance. Insulin is a hormone that helps your body use glucose -- a simple sugar made from the food you eat -- as energy. In people with insulin resistance, the insulin doesn't work as well, so your body keeps making more and more of it to cope with the rising level of glucose. Eventually, this can lead to diabetes. Insulin resistance is closely connected to having excess weight in the belly.
  • Obesity, especially abdominal obesity. Experts say that metabolic syndrome is becoming more common because of rising obesity rates. In addition, having extra fat in the belly -- as opposed to elsewhere in the body -- seems to increase your risk.
  • Unhealthy lifestyle. Eating a diet high in unhealthy processed foods and not getting enough physical activity can play a role.
  • Hormonal imbalance. Hormones may play a role. For instance, polycystic ovary syndrome (PCOS), a condition that affects fertility, is related to hormonal imbalance and metabolic syndrome.
  • Smoking.

If you've just been diagnosed with metabolic syndrome, you might be anxious. But think of it as a wake-up call. It's time to get serious about improving your health. Making simple changes to your habits now can prevent serious illness in the future.