What is metabolic syndrome? The 5 criteria and weight loss

By Eric Parker, founder of TrueCal. Published October 1, 2026. Sources checked October 1, 2026.

Written with AI assistance from the cited studies. Every claim was checked against its source. Editorial policy.

Key takeaways

You meet the definition of metabolic syndrome if you have any 3 of 5 risk factors, and no single factor is required.¹
About 1 in 3 US adults has metabolic syndrome, and people with it have about twice the risk of heart disease over the next 5 to 10 years and 5 times the risk of type 2 diabetes.¹⁴
Recommended waist cutoffs differ by population, and the 2009 statement lists separate values for several groups.¹
In a meta-analysis of randomized trials, people in lifestyle programs were about 2 times as likely to have their metabolic syndrome resolve as people in control groups.⁹
In the long-term Look AHEAD trial, the lifestyle group had about the same rate of heart attacks, strokes, heart deaths and angina hospital stays as the control group after a median of 9.6 years.¹²

What is metabolic syndrome? The short answer

Metabolic syndrome is a cluster of risk factors for heart disease and type 2 diabetes. You meet the definition if you have any 3 of these 5. The 5 are a large waist, high triglycerides, low HDL cholesterol, raised blood pressure, and raised fasting glucose. About 1 in 3 US adults has it, and people with it have about twice the risk of heart disease over the next 5 to 10 years and 5 times the risk of type 2 diabetes.¹⁴

What are the metabolic syndrome criteria?

In 2009, the International Diabetes Federation, the American Heart Association, the National Heart, Lung, and Blood Institute and other groups agreed on one harmonized definition. Any 3 of these 5 count.¹

No single factor is required. A large waist is a useful first screen, but it isn't mandatory.¹

Risk factor	Cutoff	Also counts if
Large waist	Depends on population. In the US, 40 inches or 102 centimeters or more for men, 35 inches or 88 centimeters or more for women	Not applicable¹
Triglycerides	150 milligrams per deciliter or higher	You take a drug for high triglycerides¹
HDL cholesterol	Below 40 milligrams per deciliter in men, below 50 milligrams per deciliter in women	You take a drug for low HDL¹
Blood pressure	130 systolic or higher, 85 diastolic or higher, or both	You take blood pressure drugs and have a history of high blood pressure¹
Fasting glucose	100 milligrams per deciliter or higher	You take a drug for high glucose¹

Where did these criteria come from?

The definition has changed a few times.¹

That history is why you'll see slightly different numbers on different websites.¹

1998, World Health Organization. Required evidence of insulin resistance plus 2 other risk factors.¹
2001, NCEP Adult Treatment Panel III, or ATP III. Dropped the insulin resistance test and used any 3 of 5 factors.³¹
2005, AHA and NHLBI. Kept the ATP III structure but lowered the fasting glucose cutoff from 110 to 100 milligrams per deciliter, to match the American Diabetes Association's change.²
2005, International Diabetes Federation. Made a large waist mandatory, with lower cutoffs that varied by ethnic group.¹
2009, harmonized definition. Joined the two. No mandatory factor, one set of cutoffs for everything except waist.¹

What waist size counts as metabolic syndrome?

It depends on where you're from, because the link between waist size and the other risk factors differs between groups. These are some of the cutoffs listed in the 2009 statement.¹

The NHLBI notes that your provider may use different waist values depending on your race and ethnicity.⁵

Population	Men	Women
United States, AHA and NHLBI	102 centimeters, 40 inches, or more	88 centimeters, 35 inches, or more¹
Europid, IDF	94 centimeters or more	80 centimeters or more¹
Asian, including Japanese, IDF	90 centimeters or more	80 centimeters or more¹
China, Cooperative Task Force	85 centimeters or more	80 centimeters or more¹

What causes metabolic syndrome?

Most people with metabolic syndrome have both abdominal obesity and insulin resistance. Both seem to drive the other risk factors, though the exact mechanisms aren't fully worked out.¹

The NHLBI describes the general chain this way. Fat cells, especially around the belly, raise blood levels of free fatty acids. That can make the body respond less well to insulin. Insulin resistance can then raise triglycerides and blood pressure and lower HDL. This is why metabolic syndrome is also called insulin resistance syndrome.⁶⁴

How risky is metabolic syndrome?

A meta-analysis of 87 studies and about 951,000 people found metabolic syndrome was linked to the higher risks listed below.⁸

People with metabolic syndrome but without diabetes still had raised heart risk in that analysis.⁸

About 2.35 times the risk of cardiovascular disease.⁸
About 2.4 times the risk of dying from cardiovascular disease.⁸
About 1.6 times the risk of death from any cause.⁸

Can metabolic syndrome be reversed with weight loss?

Often, yes. Guidelines name weight loss as the first priority for people with metabolic syndrome and abdominal obesity, and lifestyle change is the first-line treatment. The 2005 AHA and NHLBI statement set a first goal of about 7 percent to 10 percent of body weight over 6 to 12 months and said that much loss will reduce the severity of most or all of the risk factors. The NHLBI says losing even 3 percent to 5 percent can help with some of them.²⁷

There's a limit to what these numbers show. In the long-term Look AHEAD trial, the lifestyle group had larger early improvements in most risk factors, but after a median of 9.6 years it had about the same rate of heart attacks, strokes, heart deaths and angina hospital stays as the control group. Better numbers matter, and your clinician may still treat individual risk factors directly.¹²

The list below sums up what the trials found.⁹¹⁰¹¹

Lifestyle trials pooled. In a meta-analysis of randomized trials, people in lifestyle programs were about 2 times as likely to have their metabolic syndrome resolve as people in control groups. Blood pressure, triglycerides, waist size and fasting glucose all fell. HDL did not change significantly.⁹
Diabetes Prevention Program. About half the adults with prediabetes in this trial already had metabolic syndrome at the start. Among those who didn't, a program aiming for 7 percent weight loss and 150 minutes of activity a week cut new cases by 41 percent compared with placebo. Over 3 years, 34 percent of the lifestyle group developed it, compared with 51 percent on placebo.¹⁰
Look AHEAD. In over 5,000 adults with type 2 diabetes, losing 5 percent to under 10 percent of body weight was linked to better odds of lower blood pressure, lower triglycerides, higher HDL and lower A1C at one year. Losing 10 percent to 15 percent was linked to even better odds. LDL cholesterol was not linked to the amount of weight lost.¹¹

What is the link with fatty liver, or MASLD?

Fatty liver disease tied to metabolic problems was renamed in 2023. NAFLD, nonalcoholic fatty liver disease, is now MASLD, metabolic dysfunction-associated steatotic liver disease. The inflamed form, once NASH, is now MASH.¹³

The new name changed the definition. MASLD now means liver fat plus at least 1 of 5 cardiometabolic risk factors, such as waist size or BMI, blood pressure, and blood lipids. Those are the same kinds of measures used for metabolic syndrome, and the consensus names insulin resistance as the key problem underlying MASLD.¹³

Weight loss helps the liver too. In a study of 293 people with biopsy-confirmed NASH, 58 percent of those who lost 5 percent or more of their weight had their steatohepatitis resolve. Among those who lost 10 percent or more, 90 percent had it resolve and 45 percent saw liver scarring improve. If your liver tests are abnormal, ask your clinician what follow-up you need.¹⁴

How to track it

Three of the five criteria need a blood test or a blood pressure cuff, so your clinician's numbers are the official record. The day-to-day work happens with food and weight.¹

Measure your waist at the same spot and the same time of day, once every few weeks.
Log what you eat. A complete log shows your true average intake, which is what a weight change actually responds to. TrueCal lets you type meals in plain words, so logging takes less time.¹⁶
Watch the weekly weight average, not single weigh-ins, since daily weight swings with water.¹⁵
Keep your lab and blood pressure results with dates so you and your clinician can compare them to your weight and waist trend.

Common myths

Myth, you need all five to have metabolic syndrome. Any 3 of the 5 meet the definition.¹
Myth, the waist cutoff is the same for everyone. Recommended cutoffs differ by population, and the 2009 statement lists separate values for several groups.¹
Myth, it's still called NAFLD. The 2023 consensus renamed it MASLD, and NASH became MASH.¹³
Myth, once my numbers improve, my heart risk is solved. Improved risk factors are good news, but Look AHEAD did not show fewer heart events from lifestyle change alone in adults with type 2 diabetes. Keep up regular checkups.¹²

A note on medical advice

This article is for general information and isn't medical advice. Talk with your clinician about your own situation.

Worked example

Take an invented case of a woman with a waist of 88 centimeters, triglycerides of 150 milligrams per deciliter, HDL of 50 milligrams per deciliter, fasting glucose of 100 milligrams per deciliter, and blood pressure below 130 systolic and below 85 diastolic. Her waist, triglycerides and glucose each meet a cutoff, which makes 3 of 5. Her HDL does not count, because the cutoff for women is below 50, and 50 is not below 50. So she meets the harmonized definition. Under the older fasting glucose cutoff of 110 milligrams per deciliter, her glucose of 100 would not count, which leaves 2 of 5 and falls short of the 3 needed.¹²

A closer look

Better risk factor numbers did not mean fewer heart events in the largest long-term lifestyle trial. In Look AHEAD, in adults with type 2 diabetes, the lifestyle group had larger early improvements in most risk factors, but after a median of 9.6 years it had about the same rate of heart attacks, strokes, heart deaths and angina hospital stays as the control group.¹²

Questions and answers

Is metabolic syndrome a disease?

It's a label for a group of risk factors that tend to occur together and raise the risk of heart disease and type 2 diabetes. It is diagnosed from waist size, blood pressure and blood tests.¹⁵

How is metabolic syndrome diagnosed?

Your provider measures your waist and blood pressure and orders blood tests for glucose, triglycerides and HDL cholesterol. Any 3 of the 5 criteria meet the definition.⁵¹

How much weight loss helps metabolic syndrome?

The NHLBI says 3 percent to 5 percent can help some risk factors, and the 2005 AHA and NHLBI statement set a first goal of about 7 percent to 10 percent. Talk to your clinician about a target that fits you.⁷²

Can you have metabolic syndrome at a normal weight?

Yes. A large waist is only one of the five criteria and isn't required, so 3 of the other 4 also meet the definition.¹

Is metabolic syndrome the same as insulin resistance?

They overlap but aren't the same. Most people with metabolic syndrome have insulin resistance, and the NHLBI also calls it insulin resistance syndrome, but the diagnosis doesn't require an insulin test.¹⁴

Keep a food log with TrueCal

Type a meal in plain words and TrueCal adds it to your log, so your intake and your weight trend sit side by side.

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Sources

Circulation. Alberti. 2009.
Circulation. Grundy. 2005.
JAMA. NCEP Expert Panel. 2001.
What Is Metabolic Syndrome?. NHLBI. 2026.
Metabolic Syndrome Diagnosis. NHLBI. 2026.
Metabolic Syndrome Causes and Risk Factors. NHLBI. 2026.
Metabolic Syndrome Treatment. NHLBI. 2026.
J Am Coll Cardiol. Mottillo. 2010.
BMC Med. Yamaoka. 2012.
Ann Intern Med. Orchard. 2005.
Diabetes Care. Wing. 2011.
N Engl J Med. Look AHEAD Research Group. 2013.
Hepatology. Rinella. 2023.
Gastroenterology. Vilar-Gomez. 2015.
Physiological Reports. Bhutani. 2017.
Lancet. Hall. 2011.