Cholesterol is a fatty material that’s produced by your body and found in certain foods. While your body needs some cholesterol in order to function properly, having too much, or high cholesterol, raises your risk of a heart attack or stroke.

Because of this risk, knowing your cholesterol levels is an important part of good heart health. The American Heart Association (AHA) recommends that adults have a cholesterol test every four to six years, starting at age 20.

People with known high cholesterol levels or other chronic health conditions should get tested more often.

To prepare for a cholesterol test, you may have heard that you should fast, or avoid eating. But is fasting really necessary? The answer is maybe.

The truth is, your cholesterol can be tested without fasting. In the past, experts believed fasting ahead of time produces the most accurate results. This is because your low-density lipoproteins (LDL) — also known as “bad” cholesterol — may be affected by what you’ve recently eaten. Your levels of triglycerides (another type of fat in your blood) may also be affected by a recent meal.

New guidelines, published in the Journal of the American College of Cardiology, say that people who aren’t taking statins may not need to fast before having their blood tested for cholesterol levels.

Your doctor may recommend fasting before having your cholesterol checked. If they say you should fast, they’ll likely suggest that you avoid eating for 9 to 12 hours before your test.

For this reason, cholesterol tests are often scheduled in the morning. That way, you don’t have to spend a whole day hungry while waiting to have your test.

Cholesterol is measured using a blood test. A healthcare provider will draw your blood using a needle and collect it in a vial. This typically takes place at your doctor’s office or at a lab where the blood is then analyzed.

The test only takes a couple of minutes and is relatively painless. However, you might have some soreness or bruising on your arm around the injection site.

Your results will likely be available in a few days or within a couple of weeks.

If you aren’t already taking cholesterol medications, it may not be necessary to fast.

Depending on your situation, your doctor might recommend drinking only water and avoiding food, other drinks, and certain medications in order to make sure your results are accurate.

What else should you avoid? Alcohol. Drinking within 24 hours before your test can affect your triglyceride levels.

Your blood will likely be checked using a test called a total lipid profile. To understand your cholesterol test results, you’ll need to know the different types of cholesterol that the test measures and what’s considered normal, potentially risky, and high.

Here’s a breakdown of each type. Keep in mind that people who have conditions such as diabetes may need to aim for even lower numbers.

Total cholesterol

Your total cholesterol number is the overall amount of cholesterol found in your blood.

  • Acceptable: Below 200 mg/dL (milligrams per deciliter)
  • Borderline: 200 to 239 mg/dL
  • High: 240 mg/dL or higher

Low-density lipoprotein (LDL)

LDL is the cholesterol that blocks your blood vessels and increases your risk of heart disease.

  • Acceptable: Below 70 if coronary artery disease is present
  • Below 100 mg/dL if at risk for coronary artery disease or have a history of diabetes
  • Borderline: 130 to 159 mg/dL
  • High: 160 mg/dL or higher
  • Very high: 190 mg/dL and above

High-density lipoprotein (HDL)

HDL is also called good cholesterol and helps protect you from heart disease. This type removes excess cholesterol from your blood, helping to prevent buildup. The higher your HDL levels are, the better.

  • Acceptable: 40 mg/dL or higher for men and 50 mg/dL or higher for women
  • Low: 39 mg/dL or lower for men and 49 mg/dL or lower for women
  • Ideal: 60 mg/dL or higher

Triglycerides

High triglyceride levels coupled with high levels of LDL raise your risk for heart disease.

  • Acceptable: 149 mg/dL or lower
  • Borderline: 150 to 199 mg/dL
  • High: 200 mg/dL or higher
  • Very high: 500 mg/dL and higher

You want your cholesterol test results to fall within the acceptable ranges. If your numbers are in the borderline or high levels, you’ll need to make some lifestyle changes and may need to take medication such as a statin. Your doctor may also want to check your levels more often.

Getting your cholesterol levels tested is an important part of keeping your heart and blood vessels healthy. In general, fasting before your test isn’t required. But your doctor may recommend fasting if you’re already taking a cholesterol medication.

Be sure to ask your doctor before your test whether you need to fast.