What Is Metabolic Syndrome?
Metabolic syndrome is the name for a group of risk
factors linked to
overweight
and obesity that increase your chance for heart disease and other health
problems such as diabetes and stroke. The term metabolic refers to
the biochemical processes involved in the bodys normal functioning. Risk
factors are behaviors or conditions that increase your chance of getting a
disease. In this article, heart disease refers to
coronary
heart disease.
The five conditions listed below are metabolic risk
factors for heart disease. A person can develop any one of these risk factors
by itself, but they tend to occur together. Metabolic syndrome is diagnosed
when a person has at least three of these heart disease risk factors:
- A large waistline. This is also called abdominal
obesity or having an apple shape. Excess fat in the abdominal area
is a greater risk factor for heart disease than excess fat in other parts of
the body, such as on the hips.
- A higher than normal triglyceride level in the
blood (or youre on medicine to treat high triglycerides). Triglycerides
are a type of fat found in the blood.
- A lower than normal level of HDL cholesterol
(high-density lipoprotein cholesterol) in the blood (or youre on medicine
to treat low HDL). HDL is considered good cholesterol because it
lowers your chances of heart disease. Low levels of HDL increase your chances
of heart disease.
- Higher than normal blood pressure (or youre
on medicine to treat
high
blood pressure). Blood pressure is recorded as two numbers, usually written
one on top of or before the other, such as 120/80. The top or first number,
called the systolic blood pressure, measures the pressure in the bloodstream
when your heart beats. The bottom or second number, called the diastolic blood
pressure, measures the pressure in your bloodstream between heartbeats when the
heart is relaxed.
- Higher than normal fasting blood sugar (glucose)
(or youre on medicine to treat high blood sugar). Mildly high blood sugar
can be an early warning sign of diabetes.
The more of these risk factors you have, the greater
your chance of developing heart disease, diabetes, or a stroke. In general, a
person with metabolic syndrome is twice as likely to develop heart disease and
five times as likely to develop diabetes as someone without metabolic
syndrome.
Other risk factors aside from those of the metabolic
syndrome also increase your risk for heart disease. A high level of LDL
cholesterol (low-density lipoprotein cholesterol; considered bad
cholesterol) and smoking, for example, are key risk factors for heart disease,
but they arent components of metabolic syndrome. Even a single risk
factor raises your risk for heart disease, and every risk factor should be
lowered to reduce the risk.
The chance of developing metabolic syndrome is
closely linked to being overweight or obese and to a lack of physical activity.
Another cause is insulin resistance. Insulin resistance is a condition in which
the body cant use its insulin properly. Insulin is a hormone the body
uses to help change blood sugar into energy. Insulin resistance can lead to
high blood sugar levels and is closely linked with being overweight or
obese.
Genetics (ethnicity and family history) and older
age are other important underlying causes of metabolic syndrome.
Outlook
About 47 million adults in the United States (almost
25 percent) have metabolic syndrome, and the numbers continue to grow. The
increasing number of people with this condition is connected to the rise in
obesity rates among adults. In the future, metabolic syndrome may overtake
smoking as the leading risk factor for heart disease.
Its possible to prevent or delay metabolic
syndrome, mainly with lifestyle changes. A healthy lifestyle is a lifelong
commitment. Successfully controlling metabolic syndrome takes a long-term
effort and teamwork with your health care providers.
Other Names for Metabolic Syndrome
- Syndrome X
- Insulin resistance syndrome
- Dysmetabolic syndrome
- Hypertriglyceridemic waist
- Obesity syndrome
What Causes Metabolic Syndrome?
Metabolic syndrome has several causes that act
together. Some can be controlled, while others cant.
Causes that can be controlled include
overweight
and obesity, lack of physical activity, and insulin resistance.
Some causes you cant control are growing older
and genetics. Your chance of developing metabolic syndrome increases with age.
Your genes can increase your chances of developing insulin resistance, for
example, which can lead to metabolic syndrome, even if you have only a little
extra weight around your waist.
Two other conditions are often found in people with
metabolic syndrome, although its not known if they cause it or worsen it.
The two conditions are a tendency to form blood clots and a tendency to have a
constant, low-grade inflammation throughout the body.
Additional conditions that are being studied to see
whether they have links to metabolic syndrome include:
- Fatty liver (excess triglycerides and other fats
in the liver)
- Polycystic ovarian syndrome (a tendency to
develop cysts on the ovaries)
- Gallstones
- Breathing problems during sleep such as
sleep
apnea
Who Is At Risk for Metabolic Syndrome?
Youre at greatest risk for metabolic syndrome
if you have these underlying causes:
- A large waistline (abdominal obesity)
- Lack of physical activity
- Insulin resistance
Some people are at risk for metabolic syndrome
because the medicines they take may cause weight gain or changes in blood
pressure, cholesterol, and blood sugar levels. These medicines are most often
used for inflammation, allergies, HIV, and depression and other kinds of mental
illnesses.
Populations Affected
About 47 million adults in the United States (almost
25 percent) have metabolic syndrome. Metabolic syndrome is more common in
African American women than in African American men and in Mexican American
women than in Mexican American men. It affects White women and men roughly
equally.
Some racial and ethnic groups in the United States
are more at risk for metabolic syndrome than others. Mexican Americans have the
highest rate of metabolic syndrome (31.9 percent). Caucasians (23.8 percent)
and African Americans (21.6 percent) have lower rates.
Other groups that are at increased risk of
developing metabolic syndrome include:
- People with a sibling or parent with
diabetes
- People with a personal history of diabetes
- Women with a personal history of polycystic
ovarian syndrome (a tendency to develop cysts on the ovaries)
In addition, members of certain ethnic groups are at
increased risk for metabolic syndrome. For example, South Asians have an
increased risk for metabolic syndrome.
Risk for Heart Disease
Having metabolic syndrome increases your risk for
heart disease. Heart disease risk can be divided into short-term risk (the risk
for having a
heart
attack or dying of heart disease in the next 10 years) and long-term risk
(the risk for developing heart disease over your lifetime).
Other factors (aside from metabolic syndrome)
contribute to your risk for heart disease as well. The major risk factors
are:
- Increased LDL cholesterol (low-density
lipoprotein cholesterol) and total cholesterol levels. (LDL is the
bad cholesterol.)
- Cigarette smoking.
- Blood pressure that is greater than or equal to
140/90 (or youre on medicine for
high
blood pressure).
- Decreased HDL cholesterol (high-density
lipoprotein cholesterol) level to less than 40 mg/dL. (HDL is the
good cholesterol.)
- Age (for men ages 45 and older and for women ages
55 and older).
- Family history of early heart disease or sudden
death (in a father or brother before the age of 55, or in a mother or sister
before the age of 65).
If you smoke cigarettes or have increased LDL
cholesterol or high blood pressure, these are the first targets of
treatment.
Regardless of whether you have metabolic syndrome,
you should find out your chance of developing heart disease in the next 10
years (your short-term risk). This will help decide what your LDL cholesterol
goal should be and how you should be treated. To start, you will need to count
how many risk factors you have from the list above. (Dont count LDL and
total cholesterol because the treatment for them will be geared to your level
of risk.)
The National Cholesterol Education Program (NCEP)
divides short-term heart disease risk into four categories, as shown below.
Your risk category depends on the number of risk factors you have and which
ones they are.
Your risk factors are used to calculate your 10-year
risk of developing heart disease. The NCEP has an
online
calculator that you can use to determine your 10-year heart disease risk
score. Every person with metabolic syndrome should have their 10-year-risk
score calculated.
- Youre in the High Risk category for heart
disease if you already have heart disease or diabetes, or if your 10-year-risk
score is more than 20 percent.
- Youre in the Moderately High Risk category
if you have two or more risk factors and your 10-year-risk score is 10 to 20
percent.
- Youre in the Moderate Risk category if you
have two or more risk factors and your 10-year-risk score is less than 10
percent.
- Youre in the Lower Risk category if you
have zero or one risk factor.
Even if your 10-year-risk score isnt high,
over time metabolic syndrome will increase your chance for heart disease. This
means that, regardless of your short-term risk category, metabolic syndrome
should be treated (mainly with lifestyle changes).
What Are the Signs and Symptoms of Metabolic
Syndrome?
Metabolic syndrome is made up of a group of factors
that can increase risk even if they are only moderately raised (borderline-high
risk factors). Metabolic syndrome itself usually has no symptoms. Most of the
risk factors linked to metabolic syndrome have no signs or symptoms, although a
large waistline is a visible sign.
Some people may have symptoms of high blood sugar
(if diabetes is present) or, occasionally,
high
blood pressure. Symptoms of high blood sugar often include increased
thirst; increased urination, especially at night; fatigue (tiredness); and
blurred vision. High blood pressure is generally considered to have no signs or
symptoms. However, a few people in the early stages of high blood pressure may
have dull headaches, dizzy spells, or more nosebleeds than usual.
How Is Metabolic Syndrome Diagnosed?
The diagnosis of metabolic syndrome is based on the
results of a physical exam and blood tests. To be diagnosed with metabolic
syndrome, you must have at least three out of five of the following risk
factors:
- A large waistline. This means that you carry
excess weight around your waist (abdominal obesity). Your doctor will measure
your waist to determine whether you have abdominal obesity. A waist measurement
of 35 inches or more for women and 40 inches or more for men is a component of
metabolic syndrome and indicates an increased risk for heart disease and other
health problems. A large waistline also is called having an apple
shape.
- A higher than normal triglyceride level, or
youre on medicine to treat high triglycerides. Triglycerides are a type
of fat found in the blood. A triglyceride level of 150 mg/dL or higher is a
component of metabolic syndrome.
- A lower than normal level of HDL cholesterol
(high-density lipoprotein cholesterol), or youre on medicine to treat low
HDL. HDL is considered good cholesterol because it lowers your
chances of heart disease. An HDL cholesterol level less than 50 mg/dL for women
and less than 40 mg/dL for men is a component of metabolic syndrome.
- Higher than normal blood pressure, or youre
on medicine to treat
high
blood pressure. A blood pressure of 130/85 or higher is a component of
metabolic syndrome. If only one of your two blood pressure numbers is high,
its still a risk factor for metabolic syndrome.
- Higher than normal fasting blood sugar (glucose),
or youre on medicine to treat high blood sugar. A normal fasting blood
sugar is less than 100 mg/dL. Fasting blood sugar between 100 and 125 mg/dL is
considered prediabetes. Fasting blood sugar of 126 mg/dL or higher is
considered diabetes. A fasting blood sugar of 100 mg/dL or higher (prediabetes
or diabetes) is a component of metabolic syndrome.
About 85 percent of people who have type 2 diabetes
(the most common type) also have metabolic syndrome. These people have a much
higher risk for heart disease than the 15 percent of people who have type 2
diabetes, but dont have metabolic syndrome.
How Is Metabolic Syndrome Treated?
Healthy lifestyle changes are the first line of
treatment for metabolic syndrome. Lifestyle changes include weight loss,
increased physical activity, an improved diet, and quitting smoking.
Medicines are the next line of treatment.
Theyre used to treat and control individual risk factors such as
high
blood pressure, high triglycerides, low HDL cholesterol (high-density
lipoprotein cholesterol), and high blood sugar. Medicines such as aspirin also
may be used to reduce the risk of blood clots, a condition that often occurs
with metabolic syndrome.
Goals of Treatment
The major goal of treating metabolic syndrome is to
reduce a persons risk for heart disease. Treatment is directed first at
reducing LDL cholesterol (low-density lipoprotein cholesterol), high blood
pressure, and diabetes (if these conditions are present).
The second goal of treatment is to prevent the onset
of type 2 diabetes (if it hasnt already developed). Long-term
complications of diabetes often include heart and kidney disease, vision loss,
and foot or leg amputation. If diabetes is present, the goal of treatment is to
reduce the increased risk for heart disease by controlling all of the risk
factors.
The main emphasis in the treatment of metabolic
syndrome is to lessen the effects of the underlying risk factors that can be
controlled, such as overweight, lack of physical activity, and an unhealthy
diet.
Specific Types of Treatment
Weight Loss
In general, people with metabolic syndrome who are
overweight or obese are urged to reduce their weight by 7 to 10 percent during
the first year of treatment. For example, a person weighing 250 pounds should
try to lose 18 to 25 pounds. A person weighing 300 pounds should try to lose 21
to 30 pounds.
After the first year, people are urged to continue
to lose weight to the extent possible, with a long-range target of lowering
their body mass index (BMI) to less than 25. BMI measures your weight in
relation to your height and gives an estimate of your total body fat. A BMI
between 25 and 29.9 is considered overweight. A BMI of 30 or more is considered
obese. A BMI of less than 25 is the goal for prevention and treatment of
metabolic syndrome.
You can calculate your BMI using the National Heart,
Lung, and Blood Institutes (NHLBIs)
online calculator, or your
health care provider can calculate your BMI. For more information on losing and
maintaining your weight, see the Diseases and Conditions Index article on
Overweight
and Obesity.
Healthy Eating Plan
For a healthy eating plan, go to the NHLBIs
Aim
for a Healthy Weight Web site and the NHLBIs
"Your
Guide to Lowering Cholesterol With TLC." This booklet describes the
Therapeutic Lifestyle Changes (TLC) diet.
With the TLC diet, less than 7 percent of your daily
calories should come from saturated fat, and no more than 25 to 35 percent of
your daily calories should come from all fats, including saturated,
trans, monounsaturated, and polyunsaturated fats. You also should
consume less than 200 mg a day of cholesterol. The amounts of fat and
cholesterol in prepared foods can be found on the foods
nutritional
label.
Foods high in soluble fiber also are part of a
healthy eating plan. These foods include:
- Whole grain cereals such as oatmeal and oat
bran
- Fruits such as apples, bananas, oranges, pears,
and prunes
- Legumes such as kidney beans, lentils, chick
peas, black-eyed peas, and lima beans
Fish are an important part of a heart healthy diet.
Fish are a good source of omega-3 fatty acids, which may help protect the heart
from blood clots and inflammation and reduce the risk for
heart
attack.
You also should try to limit the amount of sodium
and salt that you eat. This means choosing low-sodium and low-salt foods and
no added salt foods and seasonings at the table or when cooking.
The nutritional label on food packaging shows the amount of sodium in the
item.
Try to limit alcoholic beverages. Too much alcohol
will raise your blood pressure and triglyceride level. It will also add extra
calories, which will cause weight gain. Men should have no more than two drinks
containing alcohol a day. Women should have no more than one drink containing
alcohol a day.
Increased Physical Activity
In general, people with metabolic syndrome are urged
to keep up a moderate level of activity, such as brisk walking for at least 30
minutes at least 5 days of the week. This activity can be broken into shorter
periods as neededfor example, three 10-minutes sessions.
The ultimate goal is for people to maintain a
moderate level of physical activity 60 minutes a day for 5 days a week, but
preferably daily. You should talk with your doctor about the best kind of
physical activity for you before starting any kind of program.
Smoking
If you smoke, quitting is important. Among other
known harmful effects on your heart, smoking will raise your triglyceride level
and lower your HDL cholesterol.
Medicines
Your doctor may recommend medicines to help treat
unhealthy cholesterol levels, high blood pressure, and high blood sugar.
Unhealthy cholesterol levels are treated by one or more cholesterol-lowering
medicines such as statins, fibrates, or nicotinic acid.
High blood pressure is treated by one or more
antihypertensive medicines such as diuretics or angiotensin-converting enzyme
(ACE) inhibitors. High blood sugar is treated with oral medicines (such as
metformin), insulin injections, or both. Low-dose aspirin can help reduce the
risk of forming blood clots, especially for people at high risk for heart
disease.
How Can Metabolic Syndrome Be Prevented?
Making healthy lifestyle choices is the best way to
prevent metabolic syndrome. Maintaining a healthy weight is important. Other
than weighing yourself on a scale, there are two ways to know whether
youre at a healthy weight: waist measurement and body mass index
(BMI).
A waist measurement indicates your abdominal fat and
is linked to your risk for heart disease and other diseases. To measure your
waist, stand and place a tape measure around your middle, just above your
hipbones. Measure your waist just after you breathe out. Make sure the tape is
snug but doesnt squeeze the flesh. A waist measurement of less than 35
inches for women and less than 40 inches for men is the goal for preventing
metabolic syndrome; its also the goal when treating metabolic
syndrome.
BMI measures your weight in relation to your height
and provides an estimate of your total body fat. A BMI between 25 and 29.9 is
considered overweight. A BMI of 30 or more is considered obese. A BMI of less
than 25 is the goal for preventing metabolic syndrome, and its also the
goal when treating metabolic syndrome.
You can calculate your BMI using the National Heart,
Lung, and Blood Institutes online calculator, or your health
care provider can calculate your BMI.
To maintain a healthy weight, follow a healthy
eating plan and try not to overeat. This means eating fewer calories and less
saturated fat, and emphasizing whole grains, fish, and fruits and vegetables.
Choose unsaturated fats when eating fats and oils such as canola, olive, or
safflower oils, soft or liquid margarine, and nuts.
Increasing your physical activity also can help you
maintain a healthy weight. Talk to your doctor about what kind of physical
activity is best for you. If youre medically able, get at least 30
minutes of moderate activity, such as brisk walking, at least 5 days a week.
With your doctors permission, work up to getting 60 minutes of moderate
activity 5 to 7 days a week.
Make sure to schedule regular doctor visits to keep
track of your cholesterol, blood pressure, and blood sugar levels. A
cholesterol blood test will show your levels of LDL cholesterol (low-density
lipoprotein cholesterol), HDL cholesterol (high-density lipoprotein), and
triglycerides.
Living With Metabolic Syndrome
Metabolic syndrome is a lifelong condition. However,
lifestyle changes can help you reverse or reduce your risk factors and reduce
your risk of heart disease and diabetes. If you already have heart disease
and/or diabetes, lifestyle changes can help you prevent or delay complications
such as
heart
attack, stroke, and the long-term effects of diabetes (damage to your eyes,
nerves, kidneys, feet, and legs).
Making healthy lifestyle changes can include
following a healthy eating plan (such as the
Therapeutic
Lifestyle Changes diet), increasing your physical activity, and quitting
smoking. Part of managing metabolic syndrome also includes taking all of your
medicines as your doctor prescribes. For more information, see the
section on treatment.
Make realistic short- and long-term goals for
yourself when you begin to make healthy lifestyle changes. Work closely with
your doctor and seek regular medical care.
Key Points
- Metabolic syndrome is the name for a group of
risk factors that increase your chance for heart disease and other health
problems such as diabetes and stroke.
- The diagnosis of metabolic syndrome is made if
you have any three out of these five heart disease risk factors: a large
waistline, a higher than normal triglyceride level, a lower than normal level
of HDL cholesterol (high-density lipoprotein cholesterol), higher than normal
blood pressure, and higher than normal fasting blood sugar (glucose).
- About 47 million adults in the United States
(almost 25 percent) have metabolic syndrome. The rate of metabolic syndrome
continues to rise as obesity levels increase.
- Metabolic syndrome has several causes that act
together. Some can be controlled, while others cant.
- To diagnose metabolic syndrome, your doctor
evaluates your risk factors and checks your waist size, cholesterol, blood
pressure, triglycerides, and blood sugar.
- The first line of treatment for metabolic
syndrome is lifestyle changes, including weight loss, increased physical
activity, and a healthy diet. If lifestyle changes cant control your risk
factors, your doctor may recommend medicines.
- Healthy lifestyle choices can help prevent
metabolic syndrome. But if you develop metabolic syndrome, healthy lifestyle
changes also can help to reverse or reduce the risk of heart disease and
diabetes and complications of those conditions.
- If you have metabolic syndrome, follow a healthy
eating plan and increase your physical activity to manage your weight; quit
smoking; and take all of your medicines as your doctor prescribes.
Links to Other Information About Metabolic
Syndrome
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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