Will Fasting Hurt Or Help Your Cholesterol Test?

Before taking a cholesterol test, adults are typically told to fast for up to 12, but that may no longer be necessary.

The study, published Nov. 12 in the Archives of Internal Medicine, found the amount of time a person spent fasting prior to a cholesterol test had little impact on the end results.

“This finding suggests that fasting for routine lipid level determinations is largely unnecessary,” wrote the authors.

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A cholesterol test, also called a lipid panel or lipid profile, measures the four types of lipids (fats) found in the blood. It measures low-density lipoprotein (LDL) cholesterol, sometimes called “bad cholesterol” because high levels of it could lead to plaque buildup in the arteries, potentially causing a heart attack and stroke.

The test also measures high-density lipoprotein (HDL) cholesterol, sometimes called “good cholesterol” because it helps carry LDL away from the blood. Cholesterol tests also measure total cholesterol and triglycerides, a type of fat found in the blood. People are typically told to have no food or liquids other than water for nine to 12 hours before the exam.

“Eliminating fasting as a general requirement for cholesterol testing could greatly increase convenience for patients without significantly altering test results,” he said.

In an accompanying editorial published in the same journal, Dr. J. Michael Gaziano, a chronic disease epidemiologist at Harvard Medical School in Boston, said the “exceedingly small” gain of information from a fasting blood test likely does not offset the logistical constraints put on patients, laboratories and doctors for the procedure.

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Study Limitations

Because the study is just a snapshot in time, it has important limitations. It doesn’t prove that cholesterol levels don’t change significantly before and after a meal for individual patients.

Researchers say the small differences noted in the study may matter for some, including those who are taking specific medications to lower their cholesterol or triglycerides. Those patients may still need fasting tests.

But for many others, eating may not make a difference.