Low HDL Cholesterol Explained
What a low HDL result means, why it usually points to insulin resistance, and what genuinely helps, in plain English.
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· · Reviewed against the sources listed at the end of this page.
The Quick Answer
HDL cholesterol is often called good cholesterol because it carries excess cholesterol away from your artery walls back to the liver. A low HDL, generally under 1.0 mmol/L (40 mg/dL) in men or 1.2 mmol/L (50 mg/dL) in women, means that clearance process is less effective than it should be.
Low HDL is rarely a problem on its own. It is usually a marker for something else: insulin resistance, high triglycerides, inactivity, smoking, or excess abdominal weight. The most useful step is not chasing the HDL number itself, but finding and treating whichever of those is driving it.
What HDL Cholesterol Actually Does
Cholesterol travels through your blood packaged inside particles, because fat and water do not mix. LDL particles carry cholesterol out to your tissues and artery walls. HDL particles do the opposite job, picking up excess cholesterol from artery walls and other tissues and returning it to the liver, where it is broken down or recycled. This process is called reverse cholesterol transport.
When HDL is low, this clearance slows down, which can allow cholesterol to accumulate in artery walls more easily over time. HDL particles also have anti-inflammatory and antioxidant properties that appear to help protect blood vessel walls independently of cholesterol transport.
The important nuance, confirmed by large drug trials over the past fifteen years, is that HDL is a better marker of cardiovascular risk than it is a direct target for treatment. Raising HDL with medication has not translated into fewer heart attacks, which is why modern care focuses on lowering LDL and improving the overall metabolic picture rather than chasing a higher HDL number.
Causes of Low HDL Cholesterol
Causes are grouped as metabolic (linked to insulin resistance and body fat distribution), lifestyle (largely reversible day-to-day factors), or medication and genetic causes, which are less common but worth knowing about.
Insulin resistance and metabolic syndrome
The single most common driver of low HDL. Insulin resistance changes how the liver packages fats, favouring high triglycerides and low HDL together, often years before blood glucose rises.
High triglycerides
HDL and triglycerides usually move in opposite directions. When triglyceride-rich particles increase, an enzyme called CETP swaps their fat for cholesterol out of HDL, shrinking and lowering it.
Excess abdominal weight
Fat stored around the abdomen and organs (visceral fat) is more metabolically active than fat elsewhere and is closely linked to both insulin resistance and low HDL, even at a normal overall body weight.
Physical inactivity
Regular aerobic exercise is one of the few reliable ways to raise HDL. A sedentary lifestyle, independent of weight, is associated with lower HDL levels.
Smoking
Lowers HDL directly and promotes insulin resistance. HDL typically starts improving within weeks of quitting.
Type 2 diabetes
Low HDL alongside high triglycerides is a hallmark of the lipid pattern seen in type 2 diabetes, sometimes called diabetic dyslipidaemia.
Anabolic steroid use
Can suppress HDL sharply, sometimes to well under half the normal level, within weeks of use. Usually recovers after stopping, though recovery can take months.
Some beta-blockers
Older, non-selective beta-blockers can modestly lower HDL. Newer beta-blockers have less effect. Never stop a prescribed medication without talking to your GP first.
Genetic lipid disorders
Inherited conditions affecting HDL production or breakdown, such as Tangier disease, are rare but cause very low HDL from a young age, often with a strong family history.
A very low-fat, high-carbohydrate diet
Replacing dietary fat almost entirely with refined carbohydrates can lower HDL and raise triglycerides at the same time, the opposite of the intended effect.
Signs That Can Accompany Low HDL
Low HDL by itself has no symptoms. What people sometimes notice are signs of the conditions that tend to cause it, particularly insulin resistance.
No direct symptoms
Low HDL itself does not cause symptoms. It is found on a routine or requested lipid profile, which is exactly why regular testing matters, especially if you have other risk factors.
Increased waist circumference
Because low HDL travels with insulin resistance, an expanding waistline (over about 94 cm for men, 80 cm for women in Australian guidelines) is often the first visible clue.
Skin tags or darkened skin folds
Acanthosis nigricans, a velvety darkening of skin at the neck or armpits, and skin tags can be visible signs of underlying insulin resistance.
Fatigue after carbohydrate-heavy meals
Some people with insulin resistance notice tiredness or a need to nap after high-carbohydrate meals, though this is not specific and many people have no such symptom at all.
Chest pain, breathlessness or leg pain on exertion
These are symptoms of established cardiovascular disease, not of low HDL directly, but they mean the process that low HDL is a marker for may already be affecting your arteries. Seek prompt medical assessment.
Family history of early heart attack or stroke
Not a symptom in you, but an important piece of context your GP will want to know, particularly a parent or sibling affected before age 55 (men) or 65 (women).
Red Flags, When to See Your GP Promptly
A mildly low HDL on its own can usually wait for your next routine check-up. Some combinations of findings should prompt a GP appointment sooner:
Chest pain, pressure or breathlessness
Whether at rest or on exertion, this needs urgent medical assessment. Call triple zero (000) for sudden, severe chest pain.
Low HDL plus high triglycerides plus high LDL
This combined pattern carries meaningfully higher cardiovascular risk than any single abnormal value and usually prompts a more active treatment discussion.
Low HDL with high blood pressure and increased waist circumference
Suggests metabolic syndrome. Worth a dedicated GP appointment to plan a structured approach rather than addressing each number separately.
Very low HDL (under about 0.7 mmol/L) at a young age
Especially with a family history of early heart disease, this warrants a more thorough workup and possibly specialist referral.
New low HDL after starting a medication
If low HDL appears soon after starting a new medication, particularly anabolic steroids or a beta-blocker, tell your GP. Do not stop a prescribed medication yourself.
What Your GP Will Do Next, The Workup
Australian GPs follow a fairly standard pathway when a lipid profile shows low HDL, usually looking well beyond the HDL number itself.
Look at the whole lipid profile, not HDL alone
Your GP will review HDL together with LDL, total cholesterol and triglycerides, and calculate ratios such as total cholesterol to HDL. A low HDL with otherwise normal lipids is viewed differently to a low HDL with high triglycerides and high LDL.
Check fasting glucose and HbA1c
Because low HDL is so closely tied to insulin resistance, a fasting glucose or HbA1c test is a standard next step to look for prediabetes or diabetes.
Measure waist circumference and blood pressure
These, together with triglycerides, HDL and glucose, are the five components used to assess metabolic syndrome. Three or more abnormal components meet the definition.
Calculate your absolute cardiovascular risk
Australian GPs use a calculator combining age, sex, blood pressure, cholesterol, smoking status and diabetes to estimate your five-year risk of a heart attack or stroke, which guides how urgently other risk factors need treating.
Review medications and lifestyle factors
Your GP will ask about smoking, alcohol, exercise, diet, and any medications known to affect HDL, including anabolic steroids and some beta-blockers.
Consider further testing if the pattern is unusual
A very low HDL at a young age, especially with a strong family history, may prompt referral to a lipid specialist to look for a genetic cause.
Treatment, What Actually Helps
Why raising HDL with drugs was abandoned
Niacin (nicotinic acid) and a class of drugs called CETP inhibitors were both shown to raise HDL substantially, in some trials by 30 percent or more. Despite this, large, well-conducted trials found no reduction in heart attacks, strokes, or cardiovascular death when these drugs were added to standard statin treatment. Several were stopped early because of side effects with no offsetting benefit. Because of this evidence, Australian and international guidelines no longer recommend medication specifically to raise HDL.
Aerobic exercise
Regular aerobic activity, such as brisk walking, cycling or swimming, is one of the best-supported ways to raise HDL, typically by 0.1 to 0.15 mmol/L with consistent effort over several months. Benefit generally increases with duration and intensity, though even modest activity helps. Australian guidelines suggest at least 150 minutes of moderate activity per week.
Quitting smoking
HDL typically begins improving within a few weeks of quitting and continues to rise over the following months. This is one of the more reliably reversible causes of low HDL. Your GP can discuss nicotine replacement, medication, and support programs such as Quitline.
Losing excess abdominal weight
Reducing visceral fat around the abdomen improves insulin sensitivity, which tends to raise HDL and lower triglycerides together. Even a modest reduction of 5 to 10 percent of body weight can produce a measurable improvement in the lipid profile.
Focusing on overall risk, not just HDL
Because raising HDL numerically has not been shown to reduce heart attacks, the current approach is to treat the whole picture: lowering LDL where indicated (often with a statin), managing blood pressure, treating insulin resistance or diabetes, and addressing the lifestyle factors above. Your GP's absolute risk calculation, not your HDL result in isolation, guides how actively that should be pursued.
Foods That Support a Healthier Lipid Profile
Extra virgin olive oil
Monounsaturated fatReplacing butter or refined vegetable oils with olive oil is one of the better-supported ways to nudge HDL upward, particularly as part of an overall Mediterranean-style pattern.
Oily fish (salmon, mackerel, sardines)
Omega-3 fatty acidsTwo serves a week is the usual Australian guideline. Omega-3s help triglycerides more directly than HDL, but lower triglycerides support a healthier HDL level over time.
Nuts (almonds, walnuts, macadamias)
Unsaturated fat, fibreA small daily handful, unsalted, is associated with modest HDL improvements in trials. Watch total energy intake if weight is also a goal.
Legumes (lentils, chickpeas, beans)
Soluble fibreHelps lower LDL and improves the overall cholesterol balance, complementing HDL-focused changes rather than raising HDL directly.
Wholegrains (oats, barley, wholemeal bread)
Soluble fibre, slow-release carbohydrateSwapping refined carbohydrates for wholegrains improves insulin sensitivity, one of the underlying drivers of low HDL.
Avocado
Monounsaturated fatA useful substitute for saturated fats such as butter and processed meats, with a favourable effect on the overall lipid profile.
Vegetables and fruit, wide variety
Fibre, antioxidantsSupports weight management and overall metabolic health, both of which influence HDL indirectly.
Foods to limit: refined carbohydrates and trans fats
Reducing intake helpsWhite bread, pastries, sugary drinks and foods containing trans fats (check labels for partially hydrogenated oils) worsen the exact pattern, low HDL and high triglycerides, that most needs improving.
Sources and reference ranges
Adult reference ranges on this page follow the AACB and RCPA harmonised reference intervals unless stated otherwise; the range printed on your own report always takes precedence because laboratories differ.
- healthdirect Australia: cholesterol
- Pathology Tests Explained (Australasian Association for Clinical Biochemistry and Laboratory Medicine)
- Australasian Association for Clinical Biochemistry and Laboratory Medicine, publisher of the harmonised reference intervals
- healthdirect Australia: full blood count
Low HDL Cholesterol, Frequently Asked Questions
What is considered low HDL cholesterol?
In Australian pathology reports, HDL cholesterol is usually flagged as low when it is under 1.0 mmol/L (about 40 mg/dL) in men, or under 1.2 mmol/L (about 50 mg/dL) in women. A level above roughly 1.3 mmol/L (50 mg/dL) is generally considered protective for heart health. Laboratories differ slightly, so always check the range printed on your own report.
Why is low HDL bad for your heart?
HDL carries excess cholesterol away from artery walls back to the liver for removal, a process called reverse cholesterol transport. When HDL is low, that clearance slows down, which allows more cholesterol to build up in artery walls. Low HDL is also a marker for the metabolic pattern behind it, usually insulin resistance and high triglycerides, which independently raises cardiovascular risk.
Can you raise HDL cholesterol naturally?
Yes. Regular aerobic exercise, quitting smoking, losing excess abdominal weight, and moderate alcohol intake (where alcohol is otherwise appropriate for you) are the changes best supported by evidence for raising HDL. Replacing refined carbohydrates with unsaturated fats such as olive oil, nuts and fatty fish also helps. Improvements are usually modest, in the order of 0.1 to 0.2 mmol/L over several months.
Do HDL-raising medications lower heart attack risk?
No, and this is one of the more important findings in recent cardiology. Niacin and CETP inhibitor drugs raise HDL numbers substantially, but large trials found no reduction in heart attacks or strokes when they were added to statin therapy. Because of this, doctors no longer prescribe medication specifically to raise HDL. The focus instead is on lowering LDL cholesterol and treating the whole risk picture.
Is low HDL linked to insulin resistance?
Yes, strongly. Low HDL combined with high triglycerides is one of the earliest and most common blood test signs of insulin resistance, often appearing years before blood glucose becomes abnormal. This combination, along with abdominal weight and blood pressure, forms part of metabolic syndrome.
Can smoking lower HDL cholesterol?
Yes. Smoking is one of the most consistent, reversible causes of low HDL. It reduces HDL both by direct effects on the liver enzymes that produce it and by promoting insulin resistance. HDL typically starts rising within weeks of quitting, with meaningful improvement over the following months.
Should I worry about a slightly low HDL on its own?
A mildly low HDL by itself, with normal triglycerides, normal LDL, healthy weight and no other risk factors, is a lower concern. Your GP looks at your whole lipid profile and overall cardiovascular risk score, not any single number. Low HDL matters most when it appears alongside high triglycerides, excess abdominal weight, high blood pressure or a family history of early heart disease.
What medications can cause low HDL?
Anabolic steroids are one of the most potent causes, sometimes dropping HDL dramatically within weeks. Some older beta-blockers and some progestin-containing hormonal contraceptives can also lower HDL modestly. If you take any of these and have low HDL, mention it to your GP rather than stopping medication on your own.
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This page provides general educational information about low HDL cholesterol. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your GP about abnormal blood test results. They have access to your full medical history and can interpret your results in context. SmarterBlood does not provide medical care and is not affiliated with any pathology laboratory or testing provider.