What causes high cholesterol is usually a mix of lifestyle habits, inherited genes and medical conditions or medicines. The National Heart, Lung, and Blood Institute (NHLBI) says an unhealthy lifestyle is the most common cause of high LDL (“bad”) cholesterol.
Genes, other health conditions and some medicines can raise it too.
That split matters because it tells you which causes you can change and which you can only monitor. This page sorts the causes that way, using NHLBI, CDC and American Heart Association pages, and ends with what a lipid panel actually measures.
What LDL and HDL cholesterol actually are
Cholesterol is a waxy, fat-like substance your body needs in the right amounts. It travels through your blood inside particles called lipoproteins, and the two you will hear about most are LDL and HDL.
NHLBI explains that high levels of LDL can build up as plaque in your artery walls, which can lead to a heart attack or stroke.
HDL carries cholesterol back to the liver to be flushed out of the body, which is why it gets the “good” label. The American Heart Association adds that your body already makes all the cholesterol it needs, so dietary extras are not required.
Video: Cleveland Clinic
The causes you can influence: lifestyle
NHLBI lists several habits tied to unhealthy cholesterol. Eating a lot of saturated fat raises LDL, and the institute says no more than 10% of your daily calories should come from it. Saturated fat is found in fatty cuts of red meat and in dairy products.
Low physical activity is linked to a higher risk of unhealthy levels. Smoking lowers HDL, particularly in women, and raises LDL. Drinking more than two drinks a day for men or more than one for women can raise total cholesterol.
NHLBI also notes that stress may raise hormones such as corticosteroids, which can make your body produce more cholesterol, and that little or low-quality sleep has been linked to poorer cardiovascular health. If stress eating is part of your picture, our guide to cortisol triggering foods covers how the hormone and diet interact.
The CDC groups diet, inactivity and smoking the same way. It adds that inactivity can lead to weight gain, which can lead to high cholesterol, and that smoking damages blood vessels so they collect fatty deposits more easily.
The causes you cannot choose: age, sex and genes
Age is the quiet one. NHLBI says high cholesterol is most commonly diagnosed between ages 40 and 59, because the liver removes LDL less efficiently as you get older. It can also appear in young children.
Sex plays a role at different life stages. NHLBI reports that between ages 20 and 39, men have a greater risk of high total cholesterol than women, while a woman’s risk goes up after menopause, when total and LDL cholesterol usually rise and HDL usually falls.
Ancestry shifts the pattern as well. NHLBI says Asian Americans are more likely to have high LDL than other groups, and Hispanic Americans are more likely to have lower HDL.
The biggest genetic cause is familial hypercholesterolemia, or FH. Some people inherit gene changes that cause very high LDL from birth. The CDC estimates that about 1 million US adults have confirmed or probable FH, and that roughly 1 in 311 people worldwide have it.
The CDC notes that FH often cannot be managed with lifestyle changes alone. The American Heart Association says people with FH face a higher risk of premature heart disease and stroke if it is not identified and treated early.
One practical flag: if a relative had a heart attack early in life, the CDC suggests talking with your health care team about your own risk and whether your family should be tested.
Medical conditions and medicines that raise LDL
This is the cause people most often miss, because nothing about it looks like a cholesterol problem. NHLBI names chronic kidney disease, diabetes, HIV/AIDS, hypothyroidism, lupus, overweight and obesity, polycystic ovary syndrome and sleep apnea as conditions to raise with your provider.
The CDC adds that type 2 diabetes lowers HDL and raises LDL, a combination that increases heart disease and stroke risk. Some prescription drugs can push the numbers the same way, including certain beta-blockers, diuretics such as thiazide, steroids such as prednisone and retinoids used for acne.
Never stop a prescription because of this list. The point is that a surprising result is worth discussing with the person who prescribed it.
| Cause | Group | Can you change it? | What the source says |
|---|---|---|---|
| Saturated fat intake | Lifestyle | Yes | NHLBI: keep under 10% of daily calories |
| Smoking | Lifestyle | Yes | Lowers HDL, raises LDL (NHLBI, CDC) |
| Physical inactivity | Lifestyle | Yes | Linked to unhealthy levels (NHLBI, CDC) |
| Age | Fixed | No | Most diagnoses between 40 and 59 (NHLBI) |
| Familial hypercholesterolemia | Genetic | Not by lifestyle alone | About 1 in 311 worldwide (CDC) |
| Type 2 diabetes, hypothyroidism, kidney disease | Medical | Managed with your provider | Listed risk conditions (NHLBI, CDC) |
| Some medicines | Medical | Only with your prescriber | Beta-blockers, diuretics, steroids (NHLBI) |
Sources: NHLBI “Blood Cholesterol: Causes and Risk Factors” (updated April 2024), CDC “Risk Factors for High Cholesterol” (May 2024).
Why you can feel fine and still have high cholesterol
High cholesterol does not announce itself, so the only way to know is a blood test. NHLBI describes a lipid panel as measuring total cholesterol, LDL, HDL and triglycerides, and says your provider may ask you to fast for 8 to 12 hours first.
NHLBI gives a general healthy-profile goal of non-HDL cholesterol below 130 mg/dL with HDL of at least 40 mg/dL for men and 50 mg/dL for women, then adds that you should check with your provider about the levels best for you. Individual targets depend on your overall heart risk.
Food claims also travel faster than the evidence. A good example of how to test one is our piece on whether tomatoes cause inflammation, and our explainer on seed oils applies the same scrutiny to another popular fat debate.
This page is general information, not medical advice. Ask your doctor for a lipid panel and talk through your own results.
Frequently asked questions
Can you have high cholesterol if you are thin and eat well?
Yes. NHLBI says genes you inherit can raise LDL, and FH can cause very high LDL from a young age regardless of weight or diet. Medical conditions and some medicines can also raise it.
What is the most common cause of high cholesterol?
According to NHLBI, an unhealthy lifestyle is the most common cause of high LDL or low HDL. That includes a diet high in saturated fat, low physical activity, smoking and heavy drinking.
Does high cholesterol run in families?
It can. The CDC says that if you have a family history of high cholesterol you are more likely to have it, and that FH is an inherited condition causing very high LDL from a young age.
