HDL — high-density lipoprotein, the so-called "good cholesterol" — is the most over-simplified value on a lipid panel. The standard headline is "higher is better." It is not that simple. The relationship between HDL and heart disease is U-shaped: very low HDL is bad, mid-range HDL is protective, and unusually high HDL (above about 80 mg/dL) appears to lose its benefit and may even be associated with increased risk.
The other twist: medications that raise HDL on a lab printout (CETP inhibitors, niacin) have repeatedly failed to reduce heart attacks. This is one of the cleanest examples in cardiology of "the number is not the goal." HDL is a marker of healthy lipid metabolism — not a lever you should pull directly.
What HDL actually does
HDL particles run reverse cholesterol transport. They scavenge cholesterol from arterial walls and tissues and shuttle it back to the liver for disposal. They also carry antioxidant and anti-inflammatory molecules. People with naturally high HDL tend to have less plaque, lower inflammation, and a lower lifetime cardiovascular risk.
But HDL on a lipid panel measures the cholesterol cargo the HDL particles are carrying — not how well those particles function. Two people can have identical HDL of 55 with very different "HDL function." The new generation of research is moving toward HDL particle number and HDL functional capacity, but those tests are not yet clinical standard.
HDL cholesterol levels chart
| Demographic | Low | High | Unit |
|---|---|---|---|
| Men — Low (risk factor) | 0 | 39 | mg/dL |
| Men — Average | 40 | 59 | mg/dL |
| Men — Protective | 60 | 80 | mg/dL |
| Women — Low (risk factor) | 0 | 49 | mg/dL |
| Women — Average | 50 | 69 | mg/dL |
| Women — Protective | 70 | 90 | mg/dL |
Reference ranges differ by sex — pre-menopausal women run higher HDL than men due to estrogen.
- Men: Below 40 mg/dL is low (independent risk factor). 40–60 is average. Above 60 is generally considered protective.
- Women: Below 50 mg/dL is low. 50–70 is average. Above 70 is generally considered protective.
The "more is better" rule has an upper limit. HDL above 80 mg/dL — particularly above 90 — has been associated with increased all-cause mortality in several large cohort studies (CANHEART, Copenhagen General Population Study). It does not mean very high HDL causes harm — it likely means it tracks with other things (heavy alcohol use, certain genetic variants, inflammation) — but it does mean the goal is not "as high as possible."
What high HDL means
HDL above 60 mg/dL has historically been treated as a "negative risk factor" — a free pass that subtracts a point from your risk score. The 2026 guidelines have softened this language because of the U-shape evidence above.
Why HDL might be high:
- Genetics. CETP loss-of-function variants are common in some populations and produce HDL of 80–120.
- Alcohol. Moderate-to-heavy alcohol intake reliably raises HDL. This is one reason the "alcohol is good for the heart" idea persisted for decades — the HDL went up, but the all-cause mortality story is much messier.
- Endurance training. Long-distance runners and cyclists often have HDL above 70.
- Estrogen. Pre-menopausal women, hormone replacement therapy.
- Some medications. Fibrates, niacin (which is rarely used now after disappointing trial results).
HDL of 95 in a non-drinker, non-runner who feels fine is usually a healthy genetic finding. HDL of 95 in someone drinking 4–6 nights a week is a flag for the alcohol, not a victory.
What low HDL means
HDL below 40 (men) or 50 (women) is an independent cardiovascular risk factor — meaning it adds risk on top of LDL, blood pressure, and the rest. Low HDL almost always travels with insulin resistance, central obesity, and high triglycerides — the metabolic syndrome cluster.
Common drivers:
- Insulin resistance and metabolic syndrome. The strongest, most common cause. HDL falls as triglycerides rise.
- Smoking. Drops HDL by 10–15%. Quitting reverses most of this within months.
- Obesity, especially visceral. Each 5 kg of weight loss raises HDL by ~1–2 mg/dL.
- Sedentary lifestyle. Aerobic exercise raises HDL more reliably than any drug.
- Anabolic steroids. Suppress HDL dramatically — often to single digits.
- Genetic conditions. ApoA-I deficiency, Tangier disease, LCAT deficiency — rare, but cause HDL near zero.
The hard truth about raising HDL: medications that selectively raise HDL on a lipid panel — niacin, fibrates, CETP inhibitors — have largely failed to reduce heart attacks in randomized trials. The right approach to low HDL is to fix the metabolic problem driving it (lose visceral fat, exercise, quit smoking, treat insulin resistance). The HDL number is a thermometer, not the fire.
Reading HDL in the context of the rest of your panel
HDL is most useful as part of a ratio:
- Total cholesterol / HDL ratio — under 3.5:1 is ideal, above 5:1 is high risk. Outperforms LDL alone in several long-term studies.
- Triglycerides / HDL ratio — under 2 is ideal, above 4 is a strong marker of insulin resistance and small-dense LDL particles.
- Non-HDL cholesterol — total minus HDL. Captures all the atherogenic particles.
HDL on its own moves slowly. Lifestyle changes show measurable HDL gains over 3–6 months — exercise (especially zone-2 aerobic work) is the most reliable lever, weight loss helps when there is visceral fat to lose, and stopping smoking adds 3–5 mg/dL within a year.
Track this biomarker over time in AskAnything.health — upload your lab results and see trends at a glance.
When to act on HDL
- HDL below 40 (men) or 50 (women) — treat the underlying metabolic syndrome (visceral fat, insulin resistance, smoking) rather than chasing the number with medication.
- HDL below 25 — investigate. Anabolic steroid use, advanced liver disease, severe inflammation, or rare genetic deficiencies are on the differential.
- HDL above 90 in someone drinking heavily — the alcohol is the story, not the HDL.
- A drop of more than 10 mg/dL between consecutive panels — review smoking, weight, and any new medications (especially androgens).
This information is for educational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider about your lab results.
Tests that complete the picture
- LDL Cholesterol — the primary treatment target.
- Triglycerides — the triglyceride/HDL ratio is one of the cleanest insulin-resistance markers on a standard panel.
- Total cholesterol — together with HDL gives you the total/HDL ratio.
- Apolipoprotein A-I — the structural protein of HDL particles. Slightly more reproducible than HDL-C but rarely measured.
- HbA1c — often reveals the insulin resistance driving low HDL.