Metabolic Syndrome

1 What is Metabolic Syndrome?

Metabolic syndrome is a group of risk factors that raises risk of heart disease, diabetes, stroke, and other health problems. It is diagnosed when any three of the following five risk factors are present:

  • High blood glucose (sugar)
  • Low levels of HDL (“good”) cholesterol in the blood
  • High levels of triglycerides in the blood
  • Large waist circumference or “apple-shaped” body
  • High blood pressure

Metabolic syndrome is a serious health condition.

According to the new IDF definition, for a person to be defined as having the metabolic syndrome they must have: 

Central obesity (defined as waist circumference* with ethnicity specific values) plus any two of the following four factors: 

  1. Raised triglycerides ≥ 150 mg/dL (1.7 mmol/L) or specific treatment for this lipid abnormality
  2. Reduced HDL cholesterol < 40 mg/dL (1.03 mmol/L) in males < 50 mg/dL (1.29 mmol/L) in females or specific treatment for this lipid abnormality
  3. Raised blood pressure systolic BP ≥ 130 or diastolic BP ≥ 85 mm Hg or treatment of previously diagnosed hypertension
  4. Raised fasting plasma glucose (FPG) ≥ 100 mg/dL (5.6 mmol/L), or previously diagnosed type 2 diabetes. If above 5.6 mmol/L or 100 mg/dl, OGTT is strongly recommended but is not necessary to define presence of the syndrome.
  • If BMI is >30 kg/m², central obesity can be assumed and waist circumference does not need to be measured.

2 Symptoms

Most of the disorders associated with metabolic syndrome have no symptoms, although a large waist circumference is a visible sign.

Clinical manifestations of metabolic syndrome include the following:

  • Hypertension
  • Hyperglycemia
  • Hypertriglyceridemia
  • Reduced high-density lipoprotein cholesterol (HDL-C)
  • Abdominal obesity
  • Chest pains or shortness of breath: Suggesting the rise of cardiovascular and other complications
  • Acanthosis nigricans, hirsutism, peripheral neuropathy, and retinopathy: In patients with insulin resistance and hyperglycemia or with diabetes mellitus
  • Xanthomas or xanthelasmas: In patients with severe dyslipidemia

3 Causes

Metabolic syndrome has several causes that act together. You can control some of the causes, such as overweight and obesity, an inactive lifestyle, and insulin resistance.

You can't control other factors that may play a role in causing metabolic syndrome, such as growing older. Your risk for metabolic syndrome increases with age.

You also can't control genetics (ethnicity and family history), which may play a role in causing the condition. For example, genetics can increase your risk for insulin resistance, which can lead to metabolic syndrome.

People who have metabolic syndrome often have two other conditions: excessive blood clotting and constant, low-grade inflammation throughout the body. Researchers don't know whether these conditions cause metabolic syndrome or worsen it.

Researchers continue to study conditions that may play a role in metabolic syndrome, such as:

  • A 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)

4 Making a Diagnosis

Several organizations have criteria for diagnosing metabolic syndrome.

According to guidelines from the National Heart, Lung, and Blood Institute (NHLBI) and the American Heart Association (AHA), metabolic syndrome is diagnosed when a patient has at least 3 of the following 5 conditions:

  • Fasting glucose ≥100 mg/dL (or receiving drug therapy for hyperglycemia)
  • Blood pressure ≥130/85 mm Hg (or receiving drug therapy for hypertension)
  • Triglycerides ≥150 mg/dL (or receiving drug therapy for hypertriglyceridemia)
  • HDL-C < 40 mg/dL in men or < 50 mg/dL in women (or receiving drug therapy for reduced HDL-C)
  • Waist circumference ≥102 cm (40 in) in men or ≥88 cm (35 in) in women; if Asian American, ≥90 cm (35 in) in men or ≥80 cm (32 in) in women

To address variation between professional guidelines, the NHLBI, AHA, International Diabetes Foundation (IDF), and others have proposed a harmonized definition of metabolic syndrome.

Complaints of chest pain, dyspnea, or claudication (symptoms of possible complications) may warrant additional studies, including the following:

  • Electrocardiography (rest/stress ECG)
  • Ultrasonography (vascular, or rest/stress echocardiography)
  • Stress single-photon emission computed tomography (SPECT) or cardiac positron emission tomography (PET)

Investigation into other causes of or exacerbating factors in metabolic syndrome should be considered. For example, sleep-related breathing disorders, such as obstructive sleep apnea, are becoming increasingly relevant and novel risk factors for metabolic syndrome.

5 Treatment

Heart-healthy lifestyle changes are the first line of treatment for metabolic syndrome. Lifestyle changes include heart-healthy eating, losing and maintaining a healthy weight, managing stress, physical activity, and quitting smoking.

If lifestyle changes aren’t enough, your doctor may prescribe medicines. Medicines are used to treat and control risk factors, such as high blood pressure, high triglycerides, low HDL (“good”) cholesterol, and high blood sugar.

Goals of Treatment:

The major goal of treating metabolic syndrome is to reduce the risk of coronary heart disease. Treatment is directed first at lowering LDL cholesterol and high blood pressure and managing diabetes (if these conditions are present).

The second goal of treatment is to prevent the onset of type 2 diabetes, if it hasn’t 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 your risk for heart disease by controlling all of your risk factors.

Heart-Healthy Lifestyle Changes :

Heart-Healthy Eating.

Heart-healthy eating is an important part of a heart-healthy lifestyle. Your doctor may recommend heart-healthy eating, which should include:

  • Fat-free or low-fat dairy products, such as skim milk
  • Fish high in omega-3 fatty acids, such as salmon, tuna, and trout, about twice a week
  • Fruits, such as apples, bananas, oranges, pears, and prunes
  • Legumes, such as kidney beans, lentils, chickpeas, black-eyed peas, and lima beans
  • Vegetables, such as broccoli, cabbage, and carrots
  • Whole grains, such as oatmeal, brown rice, and corn tortillas

When following a heart-healthy diet, you should avoid eating:

  • A lot of red meat
  • Palm and coconut oils
  • Sugary foods and beverages

Two nutrients in your diet make blood cholesterol levels raise:

  • Saturated fat—found mostly in foods that come from animals
  • Trans fat (trans fatty acids)—found in foods made with hydrogenated oils and fats, such as stick margarine; baked goods, such as cookies, cakes, and pies; crackers; frostings; and coffee creamers. Some Trans fats also occur naturally in animal fats and meats.

Saturated fat raises your blood cholesterol more than anything else in your diet. When you follow a heart-healthy eating plan, only 5 percent to 6 percent of your daily calories should come from saturated fat. Food labels list the amounts of saturated fat. To help you stay on track, here are some examples:

If you eat: Try to eat no more than:

  • 1,200 calories a day 8 grams of saturated fat a day
  • 1,500 calories a day 10 grams of saturated fat a day
  • 1,800 calories a day 12 grams of saturated fat a day
  • 2,000 calories a day 13 grams of saturated fat a day
  • 2,500 calories a day 17 grams of saturated fat a day

Not all fats are bad. Monounsaturated and polyunsaturated fats actually help lower blood cholesterol levels. Some sources of monounsaturated and polyunsaturated fats are:

  • Avocados
  • Corn, sunflower, and soybean oils
  • Nuts and seeds, such as walnuts
  • Olive, canola, peanut, safflower, and sesame oils
  • Peanut butter
  • Salmon and trout
  • Tofu


You should try to limit the amount of sodium that you eat. This means choosing and preparing foods that are lower in salt and sodium. Try to use low-sodium and “no added salt” foods and seasonings at the table or while cooking. Food labels tell you what you need to know about choosing foods that are lower in sodium. Try to eat no more than 2,300 milligrams of sodium a day. If you have high blood pressure, you may need to restrict your sodium intake even more.

Dietary Approaches to Stop Hypertension:

Your doctor may recommend the Dietary Approaches to Stop Hypertension (DASH) eating plan if you have high blood pressure. The DASH eating plan focuses on fruits, vegetables, whole grains, and other foods that are heart healthy and low in fat, cholesterol, and sodium and salt.

The DASH eating plan is a good heart-healthy eating plan, even for those who don’t have high blood pressure.

Limiting Alcohol:

Try to limit alcohol intake. Too much alcohol can raise your blood pressure and triglyceride levels, a type of fat found in the blood. Alcohol also adds extra calories, which may 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. One drink is:

  • 12 ounces of beer
  • 5 ounces of wine
  • 1½ ounces of liquor

Maintaining a Healthy Weight:

If you have metabolic syndrome and are overweight or obese, your doctor will recommend weight loss. He or she can help you create a weight-loss plan and goals. Maintaining a healthy weight can lower your risk for metabolic syndrome, coronary heart disease, and other health problems. Aim for a Healthy Weight by following a heart-healthy eating plan and keeping physically active.

Knowing your body mass index (BMI) helps you find out if you’re a healthy weight in relation to your height and give an estimate of your total body fat. A BMI:

  • Below 18.5 is a sign that you are underweight.
  • Between 18.5 and 24.9 is in the normal range.
  • Between 25.0 and 29.9 is considered overweight.
  • Of 30.0 or higher is considered obese.

A general goal to aim for is a BMI of less than 25. Your doctor or health care provider can help you set an appropriate BMI goal.

Measuring waist circumference helps screen for possible health risks. If most of your fat is around your waist rather than at your hips, you’re at a higher risk for heart disease and type 2 diabetes. This risk may be higher with a waist size that is greater than 35 inches for women or greater than 40 inches for men.

If you’re overweight or obese, try to lose weight. A loss of just 3 percent to 5 percent of your current weight can lower your triglycerides, blood glucose, and the risk of developing type 2 diabetes. Greater amounts of weight loss can improve blood pressure readings, lower LDL (“bad”) cholesterol, and increase HDL cholesterol.

Managing Stress:

Learning how to manage stress, relax, and cope with problems can improve your emotional and physical health. Consider healthy stress-reducing activities, such as:

  • A stress management program
  • Meditation
  • Physical activity
  • Relaxation therapy
  • Talking things out with friends or family

Physical Activity:

Regular physical activity can lower your risk for metabolic syndrome, coronary heart disease, and other health problems. Everyone should try to participate in moderate-intensity aerobic exercise at least 2 hours and 30 minutes per week or vigorous aerobic exercise for 1 hour and 15 minutes per week. Aerobic exercise, such as brisk walking, is any exercise in which your heart beats faster and you use more oxygen than usual. The more active you are, the more you will benefit. Participate in aerobic exercise for at least 10 minutes at a time spread throughout the week.

Talk with your doctor before you start a new exercise plan. Ask your doctor how much and what kinds of physical activity are safe for you.

Quitting Smoking:

If you smoke, quit. Smoking can raise your risk for heart disease and heart attack and worsen other heart disease risk factors. Talk with your doctor about programs and products that can help you quit smoking. Also, try to avoid secondhand smoke.

If you have trouble quitting smoking on your own, consider joining a support group. Many hospitals, workplaces, and community groups offer classes to help people quit smoking.


Sometimes lifestyle changes aren’t enough to control your risk factors for metabolic syndrome. For example, you may need statin medications to control or lower your cholesterol. By lowering your blood cholesterol level, you can decrease your chance of having a heart attack or stroke. Doctors usually prescribe statins for people who have:

  • Diabetes
  • Heart disease or had a prior stroke
  • High LDL cholesterol levels

Doctors may discuss beginning statin treatment with those who have an elevated risk for developing heart disease or having a stroke.

Your doctor also may prescribe other medications to:

  • Decrease your chance of having a heart attack or dying suddenly.
  • Lower your blood pressure.
  • Prevent blood clots, which can lead to heart attack or stroke.
  • Reduce your heart’s workload and relieve symptoms of coronary heart disease.

Take all medicines regularly, as your doctor prescribes. Don’t change the amount of your medicine or skip a dose unless your doctor tells you to. You should still follow a heart-healthy lifestyle, even if you take medicines to treat your risk factors for metabolic syndrome.

6 Prevention

Getting more exercise and losing weight can help reduce or prevent the complications associated with metabolic syndrome.

Your doctor may also prescribe medications to manage some of your underlying problems. Some of the ways you can reduce your risk:

  • Lose weight - Moderate weight loss, in the range of 5 percent to 10 percent of body weight, can help restore your body’s ability to recognize insulin and greatly reduce the chance that the syndrome will evolve into a more serious illness. This can be done via diet, exercise, or even with help from certain weight-loss medications if recommended by your doctor.
  • Exercise - Increased activity alone can improve your insulin levels. Aerobic exercise such as a brisk 30-minute daily walk can result in a weight loss, improved blood pressure, improved cholesterol levels and a reduced risk of developing diabetes. Most health care providers recommend 150 minutes of aerobic exercise each week. Exercise may reduce the risk for heart disease even without accompanying weight loss.
  • Consider dietary changes - Maintain a diet that keeps carbohydrates to no more than 50 percent of total calories. Eat foods defined as complex carbohydrates, such as whole grain bread (instead of white), brown rice (instead of white), and sugars that are unrefined (instead of refined; for example cookies, crackers). Increase your fiber consumption by eating legumes (for example, beans), whole grains, fruits and vegetables. Reduce your intake of red meats and poultry. Thirty percent of your daily calories should come from fat. Consume healthy fats such as those in canola oil, olive oil, flaxseed oil and nuts.

7 Lifestyle and Coping

Lifestyle modifications are effective in resolving metabolic syndrome and reducing the severity of related abnormalities in people with metabolic syndrome.

  • Exercise: 30-60 minutes daily of moderate-intensity aerobic activity plus an increase in daily lifestyle activities (depending on individual fitness and co-existing disease). Many studies have shown the benefits of exercise.
  • Weight loss: Weight reduction is important for those with abdominal obesity and the metabolic syndrome. The initial aim is a slow reduction of 7-10% in baseline weight, with normal body mass index as the ultimate goal.

Diet composition:

  • Fresh fruit and vegetables (at least five portions/day).
  • Complex rather than simple carbohydrates (starch not sugar); wholegrain or high-fibre rather than refined carbohydrate.
  • There is evidence showing that subjects adherent to a Mediterranean diet have lower prevalence and incidence rates of metabolic syndrome than those non-adherent.
  • Fats:
  • Reduction of dietary fat is traditional advice. However, 'low fat' is too simplistic and may even be detrimental. The composition of dietary fats is more important.
  • Avoid 'trans fats' (often labeled as 'hydrogenated' or 'partially hydrogenated' vegetable oils) as they are harmful and linked to cardiovascular disease.
  • Increase the proportion of mono-unsaturated fats (e.g., olive oil).
  • Increase the amount of omega-3 polyunsaturated fatty acids (PUFAs) compared with a Western diet.
  • Carbohydrates: the established view is that complex carbohydrates should form the major proportion of calories in the diet.

Other lifestyle factors

  • Smoking cessation.
  • Avoid excessive alcohol consumption.

8 Risks and Complications

The complications of metabolic syndrome are broad. Numerous associated cardiovascular complications exist, particularly coronary heart disease, but also atrial fibrillation, heart failure, aortic stenosis, ischemic stroke, and, possibly, venothromboembolic disease.

Emerging data suggest an important correlation between metabolic syndrome and risk of stroke.Metabolic syndrome may also be linked to neuropathy beyond hyperglycemic mechanisms through inflammatory mediators.

The metabolic derangements that characterize metabolic syndrome have been implicated in the development of nonalcoholic fatty liver disease.

In addition, metabolic syndrome has been implicated in the pathophysiology of several other diseases, including obstructive sleep apnea. Breast cancer has also been linked to metabolic syndrome, possibly through dysregulation of the plasminogen activator inhibitor-1 (PAI-1) cycle. Additional studies have linked metabolic syndrome with cancers of the colon, gallbladder, kidney, and, possibly, prostate gland.

Metabolic syndrome between pregnancies increases the risk of recurrent preeclampsia. The risk of recurrent preeclampsia increased with the number of components of the metabolic syndrome present.

Additional research has raised the possibility that metabolic syndrome adversely affects neurocognitive performance. In particular, metabolic syndrome has been blamed for accelerated cognitive aging. Patients with mental illnesses also face increased cardio metabolic risk due at least in part to socioeconomic factors such as greater poverty and poorer access to medical care.

9 Related Clinical Trials