I am almost at 72 hours of complete fasting, though I do drink coffee and tea and such. I have an order to have my blood drawn, and I’d really like to wait until I am stabilized blood-work wise, but I can’t seem to find much about how long-term fasting affects blood work.
Some background: I am 6’4 male, 400lbs and have started fasting since Sunday, as I drastically need to lose weight, I am extremely uncomfortable with being twice my healthy weight! I have so far had a great experience, I have gone from always being tired and wanting to sleep to steady energy, I have been sleeping much less and feeling much better, especially with mental energy.
I am planning on fasting for as long as possible, with medical supervision. I have an appointment with my doctor soon, and I have pending orders for blood work. My question is: how does long-term fasting affect standard blood work, and what should I be watching out for? Also, how long after beginning a fast does it take for my blood work levels to stabilize, specifically things like a basic metabolic panel and A1C levels. Any information/advice is greatly appreciated!
In essence, cholesterol will spike up during fasting. The body uses a “boat” that includes cholesterol to transport fats to your cells for energy when you aren’t eating. If you are extended fasting, more fats will be released to keep you going. More fats means more boats. This is why they tell you to fast for “12 hours” no more no less before a blood test.
The only thing I might consider is decreasing the coffee intake the day before and getting your labs drawn before you had any coffee. Cafistrol (sp?) is an oil in coffee that helps transport caffeine across the blood brain barrier but it does increase LDL p and total cholesterol. I suspect those extremely susceptible might notice a shift in their lipoproteins. If you don’t understand this stuff you might find cholesterol clarity by jimmy Moore helpful. It’s a resource I think every patient should have. Remember 200-250 seems to be the sweet spot for cholesterol.
This is what I saw:
- Cholesterol went insane. Both total and LDL went up a lot.
- WBCs, RBCs, and Platlets dropped. RBC and Platelets not by a lot.
- If you get fasting blood work your glucose probably will be low. 85 or under.
I have found the Cholesterol can normalize within a week. I am not sure about the other tests.
FYI my doctor seems unaware of the 12 hour fasting rule. She has never told me that. But clearly fasting can effect it.
*not an expert here, but returns on fasting drop at one point. some suggest 5 days should be the standard, metabolism might drop in a permanent manner. after all, fasting is a skill you develop, regardless of your objectives, a slow and steady consistent approach is better.