HDL stands for high-density lipoprotein, and on a blood test it measures the cholesterol carried by particles that move excess cholesterol out of your arteries and back to your liver. It’s often called “good cholesterol” because higher levels are linked to lower heart disease risk. For adults, 60 mg/dL or above is considered optimal, while levels below 40 mg/dL in men or below 50 mg/dL in women are flagged as low.
What HDL Actually Does in Your Body
Most cholesterol types deposit fat in your artery walls. HDL does the opposite. It picks up excess cholesterol from cells lining your blood vessels and ferries it back to the liver, where it’s either recycled or excreted through bile into your digestive tract and eventually eliminated in stool. This cleanup process is called reverse cholesterol transport, and it’s the main reason HDL is protective.
The process starts when a protein called apoA-I (the backbone of an HDL particle) arrives at a cholesterol-loaded cell. Pump proteins on the cell surface push cholesterol out onto this particle, forming a young HDL. Once the cholesterol is onboard, an enzyme converts it into a more compact form that gets tucked into the core of the particle, freeing up room on the surface for even more cholesterol. The now-mature HDL particle travels to the liver, where a receptor grabs the cholesterol cargo and pulls it inside. Some of that cholesterol also gets transferred to LDL particles along the way, which the liver then clears through a separate receptor. The net result is cholesterol moving away from artery walls and toward disposal.
How HDL Levels Affect Heart Disease Risk
A large study following 8,000 men over 21 years found that those with low HDL had roughly 36 to 38% higher risk of dying from coronary heart disease compared to men with adequate HDL levels. That elevated risk held up even in men whose total cholesterol was otherwise normal. In other words, low HDL is an independent risk factor: it raises your cardiovascular danger regardless of what your other numbers look like.
This is why your doctor pays attention to HDL separately from total cholesterol and LDL. A “normal” total cholesterol reading can mask real risk if your HDL is too low, because fewer particles are available to clear cholesterol from your arteries.
Reading Your Results
HDL appears on a standard lipid panel alongside total cholesterol, LDL, and triglycerides. Here’s how to interpret the HDL number:
- 60 mg/dL or higher: Optimal for both men and women. Associated with lower cardiovascular risk.
- 40–59 mg/dL: Acceptable, though higher within this range is better.
- Below 40 mg/dL (men) or below 50 mg/dL (women): Considered low and a risk factor for heart disease.
Your doctor may also look at your cholesterol ratio, which is your total cholesterol divided by your HDL. A lower ratio signals better balance. For example, someone with a total cholesterol of 200 and an HDL of 50 has a ratio of 4.0, while someone with the same total but an HDL of 25 has a ratio of 8.0, indicating significantly more risk.
Do You Need to Fast Before the Test?
Traditionally, lipid panels required a 9 to 12 hour fast. That’s changing. Research published in the Journal of the American College of Cardiology found that HDL cholesterol is largely unaffected by eating. While triglycerides can rise by about 26 mg/dL after a meal, HDL stays essentially the same whether you’ve fasted or not. Multiple guidelines from cardiology societies in Europe, Canada, the U.S., and elsewhere now state that fasting is not routinely required for a lipid profile. Your lab or doctor may still request fasting for the most accurate triglyceride and LDL readings, but your HDL result will be reliable either way.
What Lowers HDL
Several common factors push HDL down. Smoking is one of the most potent, and quitting reliably raises it. Carrying excess weight, especially around the midsection, is strongly associated with low HDL. A diet high in refined carbohydrates and trans fats also suppresses it. Physical inactivity plays a major role as well, since regular movement is one of the strongest natural HDL boosters.
Certain medications can lower HDL as a side effect, particularly beta-blockers and some older blood pressure drugs. Type 2 diabetes and metabolic syndrome are both linked to depressed HDL levels, often alongside high triglycerides.
In rare cases, genetics are the primary driver. A condition called familial HDL deficiency results from inherited mutations in genes responsible for building the HDL particle or pumping cholesterol onto it. People with one copy of the affected gene have chronically low HDL. Those who inherit two copies of a mutation in the ABCA1 gene develop Tangier disease, a more severe form that causes orange-colored tonsils, nerve problems, and cloudy corneas alongside extremely low HDL.
How to Raise HDL
Aerobic exercise is the most consistent lifestyle intervention. A systematic review of exercise studies found that regular aerobic training increases HDL while simultaneously lowering LDL and triglycerides. The effect is dose-dependent: more frequent and more vigorous activity tends to produce a larger HDL increase. Even moderate activity like brisk walking for 30 minutes most days of the week moves the needle.
Dietary changes help too, though the effect on HDL is more modest than exercise. Replacing refined carbohydrates with unsaturated fats from sources like olive oil, nuts, and fatty fish tends to raise HDL. Moderate alcohol consumption (one drink per day for women, up to two for men) is associated with higher HDL, but the cardiovascular tradeoffs of alcohol make this a complicated recommendation.
Losing excess weight has a dual benefit. For roughly every 6 pounds lost, HDL rises by about 1 mg/dL. That sounds small, but combined with the improvements in triglycerides, blood pressure, and insulin sensitivity that come with weight loss, the cumulative cardiovascular benefit is substantial. Quitting smoking raises HDL by an average of several points within weeks, with continued improvement over the following months.
When lifestyle changes aren’t enough, statins prescribed for high LDL also produce a modest HDL increase. Specific medications targeting HDL directly have had a complicated track record in clinical trials, so treatment decisions typically focus on lowering LDL and triglycerides while supporting HDL through habits.