When your healthcare provider orders certain tests, you may be told to fast for several hours before the test or overnight.

What is Fasting?

Fasting is when you consume no food or drinks, with the exception of water, for a set period of time. It is important to drink plenty of water, not just because you are not eating, but because it is easier to draw blood from your veins when you are well hydrated.

Why Fasting is Necessary?

The nutrients in the food and beverages you consume are absorbed into your blood stream and could impact factors measured by certain tests. Tests to determine your lipid levels (cholesterol, triglycerides and HDL) usually require fasting. You will also be told to fast before glucose testing. Other tests may also require fasting. If you don’t fast, or fast for a shorter time than prescribed, your tests could give inaccurate results, meaning you will likely have to repeat the test.

Continue to Take Medications

Be sure to take your usual medications unless told otherwise by your healthcare provider. If you are taking vitamin/mineral supplements, ask whether you should continue to take those as well.