When you need to fast for labs, you might think a small sip of smoothie here or one bite of toast there won't make a huge difference. Here's why fasting is important for the most accurate lab results on your baseline blood levels.
What is fasting?
Fasting refers to a period of time when you do not eat or drink anything. When fasting for lab work, you should avoid all foods and beverages except water at least 8 hours before your test is done.
Why is fasting important?
When you consume food and beverages, your bloodstream absorbs nutrients such as sugars and cholesterol. This increases the levels of sugar and cholesterol that are detected in your lab results. Nutrient absorption affects many processes in your body that will also alter lab results.
What can I consume when fasting?
Unless your care team instructed you otherwise, do not eat or drink anything other than water for 8 hours leading up to your lab visit.
How to make it easier.
If fasting for 8 hours sounds difficult, here are some tips that might make your experience better:
- Schedule your visit for the morning so your fast happens while you sleep.
- Bring a snack to eat as soon as your labs are done.
- Stay hydrated by drinking water the day of your appointment.
Sources:
https://www.webmd.com/cholesterol-management/fasting-blood-tests
https://medlineplus.gov/lab-tests/fasting-for-a-blood-test/
https://www.healthline.com/health/fasting-before-blood-test#takeaway
https://www.verywellhealth.com/fasting-for-blood-work-5217491
https://www.mcgill.ca/oss/article/medical-student-contributors/you-are-when-you-eat