Revealing the secret of 'not eating anything before taking blood' and what happens if we 'accidentally eat'

Let's decode this secret to better understand the requirements that doctors give!

When going for a routine health check-up, you have probably been asked by your doctor to "fast" before a blood test.

So why is this rule in place? Can what you eat or drink alter your test results to the point where it misdiagnoses your health condition?

Let's decode this secret to better understand the requirements that doctors give!

Why fast before blood test?

According to information from Webmd: When you eat or drink, nutrients from food quickly enter the bloodstream, changing test results.

Fasting ensures that test results accurately reflect your health status, without being affected by temporary fluctuations from your last meal.

Some tests that require fasting include:

1. Fasting Blood Glucose Test: To measure blood sugar accurately, especially for patients at risk or with diabetes.
2. Lipid Profile: Measures blood cholesterol and triglyceride levels to assess risk of cardiovascular disease.

Eating before the test can cause triglyceride levels to spike, leading to inaccurate results.

Comprehensive Metabolic Panel: This test measures liver and kidney function, glucose levels, and electrolytes in the body. Fasting helps eliminate temporary fluctuations in these levels.

Vitamin and mineral tests such as iron, vitamin B12 : Assessment of deficiency or excess levels may be affected if you have recently eaten or drunk before the blood sample is taken.

Gamma-glutamyl transferase (GGT) : Measures the level of the enzyme GGT in your body. Elevated levels may indicate liver disease, bile duct problems, or alcohol abuse.

Kidney function panel assesses your kidney health : Your doctor may order this test as part of a general health checkup or if you have a problem with your kidneys.

How long should I fast before a blood test?

The required fasting time usually ranges from 8 to 12 hours, depending on the type of test you are having.

For example, for fasting blood glucose and lipid profile tests, the typical fasting period is 8-12 hours. Other tests such as liver or kidney function tests also require fasting for a similar period of time.

Note that you should only drink water during your fast. Beverages containing caffeine, such as coffee and tea, can affect the test results.

Avoid smoking, chewing gum, or strenuous exercise before the test, as these activities can also alter blood levels.

What happens if you 'accidentally eat' before the test?

If you accidentally eat or drink before the test, it is important to tell the phlebotomist or doctor right away. Food can affect the accuracy of the results, especially blood sugar and cholesterol. In this case, your doctor may ask you to reschedule your appointment to ensure the most accurate results.

For example, if you eat a carbohydrate-rich meal before a blood sugar test, your blood sugar level may spike and give a false diagnosis of diabetes or prediabetes.

Important notes when fasting before blood test

1. 1. Drink enough water: Drinking water helps keep the body hydrated, making veins easier to see when taking blood.
2. 2. Do not drink coffee, tea, or soft drinks: These drinks contain caffeine and sugar which can alter test results.
3. 3. Limit the use of supplements and medications (unless prescribed by a doctor) before the test.

It is important to strictly adhere to fasting requirements before a blood test to obtain the most accurate results. If you are unsure about specific requirements, check with your doctor or healthcare professional before having the test.