What You Should Know About Fasting Before a Blood Test

When the blood has been taken out of your hand or arm and the needle has been extracted, you should put pressure with a cotton ball on the site in order to stop the bleeding from the vein. Then the cotton ball or some type of bandage will be placed over the site of blood collection. If you happen to be allergic to tape or to alcohol swabs, let the lab technician know prior to having the test done.

Can I Drink Water When Fasting?

When you need to fast because you are supposed to have some lab tests, you might have to fast for up to 12 hours before having the test. Certain tests require fasting, such as cholesterol testing, glucose testing, etc. Ask your healthcare provider if you need to fast before having a certain test done. You should definitely stay away from alcohol for a full day before having your blood taken. Yet, for any unsure questions, just ask your doctor and you may be surprised at the answer.

Why Do I Need to Perform Fasting?

Before asking yourself, “can I drink water when fasting,” let’s first find out why you should fast before having certain blood tests done. Various substances contained in the beverages and foods you take enter into your blood, which can impact the results of certain blood tests. Usually, you will be required to fast before a blood glucose test. Similarly, you will need to fast before a lipid profile, which measures total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides. There may be other tests which require you to fast. If you fail to fast or don’t fast the whole time required, the test results could be inaccurate. This will mean you will have to do the blood test all over again. If you don’t think you will be able to fast, talk to your doctor before having the test.

Detailed Questions for Fasting

Below are some frequently asked questions regarding fasting. Continue to see if your wanted answers are covered.

1. Can I Drink Water When Fasting?

Yes, you can. It is perfectly okay to drink water when fasting. Actually, it is the only thing you can take into your body during the fasting period. Additionally,water intake can make you feel better during the fast and the blood drawing will be easier. Blood contains 50% water, so with enough fluid in your system, your veins will be more readily available and the lab tech will have an easier time taking out the blood.

Two related question:

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• Can I drink juice? No, only water can be consumed during a fast.
• Can I drink coffee? No, you should not drink any kind of coffee or tea during the fasting period.

2. What Is the Duration of Fasting?

Before having blood sugar drawn or a lipid profile, your doctor will have you fast for as long as 8 hours. Yet, your doctor may have different instructions regarding fasting for you and you should follow the recommendations whenever possible.

You can have something to eat or drink as soon as the blood is drawn. So, it is best to bring a snack along with you. Also, it is a better idea that you appoint the blood test in the morning so that you will spend the most time of fasting while sleeping.

3. Should I Continue Medications When Fasting?

Usually, you need to continue the medications you have been taking when fasting, unless your doctor tells you not to. As for supplements like vitamins and minerals, you should your doctor’s advice. Just don’t mess up your medication schedule or forget to take an important medication during the fasting period.

4. More Facts You Should Know

There are several questions you may have besides “can I drink water when fasting?” These include the following:

• Can I chew some gum? No, you shouldn’t even have sugarless gum as this can cause stimulation of the GI tract and can mess up the lab tests.
• May I exercise? No, exercising can alter the results of the testing.
• Can I smoke? No, smoking can adversely affect the results of the test.

What to Expect During the Procedure

After figuring out the answer to the questions like can I drink water when fasting, you will naturally want to know how the test is done. Below are some common procedures you may experience in your test.

Step 1: Confirm and Position You

First, you need to complete the paperwork which confirms that you have been fasting for the required time. Then the lab technician will take a look at your arm and hands to find a vein that is suitable for taking blood from. For any discomfort like faint, just inform the blood tester or collector, and s/he can talk you through your discomfort. You might decide that it is better to lie down for the test in order to avoid fainting or vomiting during the test.

Step 2: Get the Blood

When the lab technician has found a vein that is suitable to take blood from, he or she will take an alcohol swab and clean off the skin so that bacteria don’t adversely affect the blood test. With needle and collection device being prepared, the technician will use a sterile needle to make a puncture hole into the skin and through the vein to get the blood sample.

Step 3: Label the Tubes

The lab technician will make use of different collection tubes in order to put various amounts of the collected blood in. The blood test may require just one tube of blood or several tubes of blood, depending on the test. All the tubes used to collect your blood will have a label put on them that identifies you by your name and your birth date.

Step 4: After the Blood Collection

When the blood has been taken out of your hand or arm and the needle has been extracted, you should put pressure with a cotton ball on the site in order to stop the bleeding from the vein. Then the cotton ball or some type of bandage will be placed over the site of blood collection. If you happen to be allergic to tape or to alcohol swabs, let the lab technician know prior to having the test done.

You shouldn’t lift anything heavy or do any type of physical exercise for a day or so after the test, so that the area doesn’t begin to bleed again or doesn’t bruise.

What You Should Know About Fasting Before a Blood Test

So, your healthcare provider has asked you to fast before your blood test. Fasting means not eating and drinking for a period of time. You often need to do this before bloodwork. This is because what you eat and drink ends up in your bloodstream and can skew your results.

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But can you drink black coffee when fasting for bloodwork? How about taking your medications? Family medicine specialist Timothy Tramontana, MD, MS, answers your frequently asked questions.

Q: How long should you fast for a blood test?

A: Typically, you should fast before bloodwork anywhere between 10 and 12 hours. Usually, people choose to do blood tests first thing in the morning. This way, you can fast overnight, when you generally don’t eat anyway.

Types of fasted blood tests

Blood tests are a quick, effective way for doctors to check your health and to see if certain treatments are working. Blood tests you may need to fast for include:

• Basic metabolic panel: Measures overall body function.
• Blood glucose test: Measures glucose (sugar).
• Cholesterol test: Measures cholesterol and triglycerides, a type of fat. Also called lipid panel or lipid profile.
• Liver function test: Measures liver health by checking proteins, liver enzymes and bilirubin.
• Renal function panel: Measures kidney function.

Q: Can you drink water before a fasting blood test?

A: Yes. You can drink as much water as you want, but it should be plain. Avoid lemon-flavored and carbonated waters, as well as teas until after your test.

Q: Can you drink black coffee when fasting for bloodwork?

A: Don’t drink anything but water. Coffee contains caffeine. It’s also a diuretic, which removes water from your body. Many people think coffee counts toward your fluid requirements. However, it makes you urinate more, which can affect some of your lab results. So, get your blood test done, then get your cup of coffee!

Q: Can you take medication before a fasting blood test?

A: You can take over-the-counter and prescription medications unless your doctor advises you otherwise. On that note, it’s definitely a good idea to tell your doctor about all medications and supplements you’re taking to avoid something potentially skewing lab results.

There’s no indication that daily medications — such as blood thinners and blood pressure meds — will cause any problems with fasting bloodwork, so definitely continue taking them unless told otherwise. And if you have a headache, taking an ibuprofen or another over-the-counter pain reliever shouldn’t cause any issues.

Q: What if you forgot to fast or ate something by accident?

A: Let your doctor know so you don’t end up doing a test unnecessarily. If you’ve already gone for the test without fasting, and the results come back normal, then you’re most likely OK. But if results come back abnormal, that may mean you have to redo the bloodwork while fasting.

Q: What if you have more questions about your test?

A: Call or send a message to your primary care team. Someone should be able to field your questions so you can feel as prepared as possible.

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Can You Drink Water While Fasting?

Intermittent fasting is alternating between eating and fasting during specific hours of the day. You can drink water while fasting, but you should be under medical supervision if you’d like to fast for more than one to three days.

Recent research has demonstrated the benefits of intermittent fasting. Unfortunately, understanding what you can eat or drink during a fast can get confusing. One of the most common questions is: “Can you drink water while fasting?”

The answer to this isn’t straightforward and depends on factors such as the purpose and the type of your fast. This article will explore whether you can drink water during certain fasts and what other factors you should be aware of.

A widespread weight-loss practice includes intermittent fasting, in which you alternate between eating and fasting during specific hours of the day. While regular diets focus on what you eat, the goal of intermittent fasting is to monitor when you eat. Research has found this an effective method for managing weight.

A 2015 study found that eating frequently is linked to obesity or being overweight. According to the study, people who ate more than four times a day were 50% more likely to be overweight or obese than those who ate a maximum of three times a day. The study involved more than 18,000 American adults over 20.

One of the most common intermittent fasting practices is eating during an eight-hour period of your choice — typically from 10 am to 6 pm — and fasting for the remaining 16 hours. This intermittent fasting leads to a period of zero calorie intake after your body has burned the calories you ate during your last meal, causing your body to break down stored fat — a process called metabolic switching.

Research shows intermittent fasting reduces the risk of several chronic conditions, such as age-related neurodegenerative diseases, inflammatory bowel disease, and cancers. Intermittent fasting also enhances brain functions, especially verbal memory, and burns body fat without sacrificing muscle mass. Since intermittent fasting focuses mainly on limiting your calorie intake, though, there’s no restriction on drinking water.

Water-only fasting

Water fasting involves drinking only water while abstaining from solid food for a period of time generally lasting one to three days (or longer, if you are under direct medical supervision). There are many reasons to go on a water fast. A primary reason to start is to reduce caloric intake to lose weight.

Research suggests there are some benefits of water fasting. A 2021 study involving 45 healthy participants found that water-only fasting reduces the risks of metabolic disorders and inflammation-related conditions. According to the study, fasting slows down your aging process and causes a noticeable reduction in body weight, waist circumference, and body mass index (BMI). Water-only fasting also has other health benefits.

Lowers your blood pressure

A 2014 study involving 174 participants with hypertension found that water fasting helps lower blood pressure. According to the study, medically supervised water-only fasting reduced the participants’ blood pressure considerably. At the end of the study, the participants did not feel the need to take any other medication for their hypertension.

Could improve heart health

According to research, water-only fasting lowers the risk of cardiovascular diseases. One such study involving 30 healthy participants found that water-only fasting increases the red blood cell count, human growth hormone, and hemoglobin. The study also recommends frequent short-term fasting as a method to counter the risks of metabolic diseases. Still, more research is needed to understand the long-term effects of water-only fasting on heart health.

Improves kidney function

A 2018 study found that water-only fasting improves kidney function, reduces oxidative stress, and lowers bad cholesterol (LDL cholesterol) levels. Unchecked oxidative stress causes a spike in the number of reactive molecules in your body that can lead to cell and tissue damage.

QUESTION

Fasting for medical procedures

Some medical procedures require you to be on a water-only diet for roughly eight to 12 hours before the procedure. This ensures that you’re on an empty stomach to minimize the risk of any complications during surgery.

You should also fast before some medical procedures to prevent lung damage. Under normal circumstances, your body prevents the contents of your stomach from entering the lungs, but anesthesia limits your body’s ability to do this. When food or stomach acids enter your lungs, that can lead to infections and lung damage.”

Can you drink water while fasting?

While most health experts suggest you can drink water while fasting, that depends on your purpose. Those who fast for religious purposes may forgo water as well, even if that is not the healthiest decision.

Others may fast for their health. Fasting burns calories and helps keep your weight in check. A lot of research indicates fasting is good for health, whether that involves intermittent fasting, water-only fasting, or both. However, the long-term effects of such fasts are still to be understood. Your body does not get enough calories when you fast, and this could cause:

• Dehydration
• Inadequate electrolyte levels in your body
• Heart arrhythmias
• Lower metabolism
• Constipation
• Erratic blood sugar levels
• Lightheadedness

If you think a water-only fast is not for you, there are other options you can explore. In addition to water, you can add other clear liquids to your diet. These include:

• Fruit juices without pulp
• Sports drinks
• Carbonated drinks
• Tea and coffee
• Clear broths

On the other hand, you may wish to avoid items such as milk and orange juice, as they contain more nutrients and may take more work for your metabolic system to break down.

If you want to lose weight, check with your doctor whether fasting is safe and what you can eat or drink during such fasts.

In addition to children and teens under 18, the following people should avoid fasting:

• Pregnant women
• Women who are breastfeeding
• Individuals with diabetes
• People with a history of eating disorders

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