How long to fast for blood work?

Answer 1

If you are doing a standard blood glucose test, 30 minutes to an hour after a meal usually gives the best indication. The problem with the accuracy lies in the glycemic index of the foods consumed during the meal. The glycemic index is important as high index foods break down in the digestive system and spread out the nutrients, sugars and fats quickly and low index foods take longer to break down.

Another problem is that not all high and low glycemic index foods mean bad and good respectively, they vary. Sweets like jelly beans are extremely high in glucose, but are a very high index food, so it breaks down in the system quickly and the sugar levels drop not long after. Doesn't mean they are better for you, it just means they give a hard sugar fix quickly and that is not really a good thing. At the same time, you don't want to be eating a sweet food that is a low index as the sugar levels stay high for too long and make levels difficult to control.

If you a doing a specific glucose stress test, like one ordered by a doctor or one done at a pathology clinic, then 2 hours after you eat, but this test is usually designed to give you plenty of glucose to see how well your system can break it down.

Answer 2

For lipids at least 9 hours. 12 hours is often recommended

Answer 3

pretty sure it's 16 hours

Answer 4

12 hours