What should you not eat the day before a blood test?

Asked By: Gregori Isser | Last Updated: 10th June, 2020
Category: medical health diabetes
4.6/5 (271 Views . 18 Votes)
Fasting Requirements
Fasting means that, with the exception of water, you refrain from eating or drinking for a minimum of 8 hours (10 to 12 hours is preferable) prior to the draw. This means no coffee or tea, so save that morning trip to the café for after your draw. Taking your vitamins or medications is OK, though.

Click to see full answer


Subsequently, one may also ask, does what you eat the night before affect blood test?

So, if a person eats food before the iron blood test, the results may show inflated levels of iron. To ensure accurate results, people are asked not to eat anything on the morning of the test. Some people may take iron supplements or multivitamin tablets that contain iron. These can also affect results.

Furthermore, what should you eat before getting blood drawn? With certain blood tests, you may be instructed to fast for up to eight hours before your appointment. Fasting before a blood draw means you don't eat or drink anything except water. Don't wait until the day of your blood draw to ask if you should fast.

Also Know, what happens if you don't fast before a blood test?

A: If you don't fast before a test that requires it, the results may not be accurate. If you forget and eat or drink something, call your provider and ask if the test can still be done. And if fasting is an absolute must for meaningful results, they should stop and reschedule your blood draw.

What should you not do before a blood test?

Before Your Blood Test

  • Fast Smartly. Fasting for a blood test entails avoiding all food and beverages (except for water) for 8 to 12 hours prior to the test.
  • Drink Water. Many people believe they should avoid water before a blood draw, but this couldn't be further from the truth.
  • Insurance Coverage.

28 Related Question Answers Found

Can you brush your teeth when your fasting for a blood test?

?Yes, brushing your teeth is permitted unless otherwise indicated by your physician, assuming you do not use large amounts of toothpaste and swallow the lather.

What should you not do before blood work?

Fasting Requirements
Fasting means that, with the exception of water, you refrain from eating or drinking for a minimum of 8 hours (10 to 12 hours is preferable) prior to the draw. This means no coffee or tea, so save that morning trip to the café for after your draw. Taking your vitamins or medications is OK, though.

What should I not eat the night before my glucose test?

Do not eat, drink, smoke, or exercise strenuously for at least 8 hours before your first blood sample is taken. Tell your doctor about all prescription and nonprescription medicines you are taking. You may be instructed to stop taking certain medicines before the test.

Does what you eat the day before affect glucose test?

For a fasting blood glucose test, you can't eat or drink anything but water for eight hours before your test. You may want to schedule a fasting glucose test first thing in the morning so you don't have to fast during the day. Certain medications can affect blood glucose levels.

Are cholesterol tests affected by food eaten the day before?


Fasting for 10 to 12 hours before a cholesterol test ensures that a single food or meal does not affect the outcome of the test. However, if you ate a cheeseburger every day, that probably would affect your numbers. Cholesterol levels are affected by what you eat over time.

How long do I really need to fast before a blood test?

Please ensure that you have nothing to eat or drink (other than water) for 8-12 hours prior to presenting for the test. It is recommended that you fast for 8 hours for a 'Fasting glucose' and 10-12 hours for 'cholesterol/lipid' testing. 2. Do not fast for any longer than 12 hours, as this may affect your test.

Can I take medication before a fasting blood test?

If your doctor orders a fasting blood test, you should not have anything to eat or drink for 12 hours before you go to the laboratory to have your blood taken. Yes, you should take any medication which has been prescribed to you by your doctor unless your doctor tells you not to.

Do you really have to fast for 12 hours before a blood test?

Fasting means you don't eat or drink anything but water usually for 8 to 12 hours beforehand. If it's a 12-hour fast, avoid food and drink after 8 p.m. the night before. You also shouldn't smoke, chew gum (even sugarless), or exercise. These things can rev up your digestion, and that can affect your results.

How can I make a blood test easier?

Drink plenty of water before your appointment. When you're hydrated, your blood volume goes up, and your veins are plumper and easier to access. Eat a healthy meal before you go. Choosing one with plenty of protein and whole-grain carbohydrates may prevent you from feeling light-headed after giving blood.

Does fasting for 12 hours work?


Fast for 12 hours a day
According to some researchers, fasting for 10–16 hours can cause the body to turn its fat stores into energy, which releases ketones into the bloodstream. This should encourage weight loss. This type of intermittent fasting plan may be a good option for beginners.

How does dehydration affect blood tests?

Effect of dehydration on CBG measurements
Hypotension as a result of dehydration results in decrease in perfusion and increase in glucose utilisation in the local tissue leading to false low results of capillary blood glucose (CBG) tests.

HOW DOES NOT fasting affect your cholesterol test?

The truth is, your cholesterol can be tested without fasting. 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.

What is the purpose of fasting before a blood test?

It is important that a person has not had anything to eat or drink other than water for 8 to 10 hours before a fasting blood glucose test. Fasting helps ensure that the blood test records an accurate measure of fasting blood sugar levels. The results help a doctor to diagnose or rule out diabetes.

Does coffee increase blood sugar?

After meals, your blood sugar rises higher than normal. Caffeine may make it tougher to bring it down to a healthy point. This may lead to too-high blood sugar levels. Over time, this may raise your chance of diabetes complications, like nerve damage or heart disease.

Can drinking the night before a blood test affect liver enzymes?


Food and drink before the test may affect the results. Drinking a lot of alcohol within a day or two of the test can cause abnormal results. It's recommended that you avoid alcohol for about 48 hours before the test.

What should you not do before a physical exam?

Salty, fatty foods elevate your blood pressure and triglycerides. It's best to avoid them for at least 24 hours before your exam, and two or three days would be even better.

How much water should you drink before having blood drawn?

If your phlebotomy specialist says it is OK to drink water before getting blood drawn, try to drink the recommended daily amount of water, which is 64 ounces.