Hello Tuesday. Tonight I’ll hit on some recent questions. These are quick responses, but I will update (probably this weekend) if I see something lacking . . . or if you tell me something is lacking!
Q1: Acetone in urine is a waste product, but is Bbh (beta-hydroxybutyric acid) in blood is a waste product of ketones used or not?
Ketone bodies (acetone, aceto-acetic acid, and beta-hydroxybutyric acid) are by-products created when you use fat, rather than glucose, to fuel your body. Ketones are a waste product.
The ketone bodies acetoacetate and β-hydroxybutyrate can be reconverted to acetyl-CoA to produce energy. The heart gets much of its energy from ketone bodies, although it also uses a lot of fatty acids. The brain gets its energy from ketone bodies when insufficient glucose is available (e.g. fasting). Almost every organ and cell can use ketone bodies for energy. Your body can produce the glucose those remaining cells: Red Blood Cells and organs: Liver from the glycerol backbone on a triglyceride . . . aka FAT! So you can get the glucose any part of your body needs even if you never consume glucose again.
Q2: How do we know empirically that a particular part of the body is using ketones?
In brief, we don’t know empirically . . . at least without biopsies. That’s a bit too invasive for home tests.
Q3: Is there any specific way to measure what the brain is using?
Yes, but it’s complicated and not something you can do at home. Womp. Womp. See this for details on testing https://www.ncbi.nlm.nih.gov/pubmed/19227486/ and this for newer details on testing:
Brain scans are available in many markets. If my experience is any indicator, the benefit you get from any scan is directly related to how skilled your scanner and interpreter are. Skip the groupon deals on this stuff.
Q4: How do we measure how much glucose we need to use up before switching to ketones?
Size does matter. Smaller people will have less storage area than a taller similar body style. The rule of thumb for an average sized male (now 180# 5’10”) is that the body can store 2000 calories of glucose. That same male will burn an additional 100 calories per flat mile walked (or run) above basal metabolic rate. So he’s got 20 miles of glucose in him.
For a female at 110# 5’6″ the storage is probably less than 2000, maybe 1500 – total guess. But she only gets 50 calories per flat mile walked or run above BMR. That should make sense, she’s moving less mass. She probably has 30 miles of glucose in her.
You do need to use up the glucose circulating and stored in the most accessible spots before the liver will motivate to pull apart fat molecules to create ketone bodies. As your body starts to remember how to use ketones as the primary fuel (which you would have done as an infant), more and more organs will switch over to ketone usage.
Q5: How to expedite use of the glucose stores?
Yes, excellent question. This response is for those who specifically want to expedite the use of the glucose stores.
In the miles example above, you could super-load with a 20/30/40 mile walk – no fuel along the way – none. Water and salt only. But that’s kinda miserable. Or you could stop eating carbs completely until you notice ketone in your urine (or blood you pricking braves). Or you could consider fasting and even fasting with exercise.
The fastest way to use up glucose stores is to fast. Salted water and that’s it. Use a BMR calculator to estimate your daily BMR (unless you’ve done the resting metabolic rate test and “know” your number). Your storage of free-glucose is probably 1500 to 2400. Your body will use up that glucose energy first. Estimate of glucose storage: X. Estimate of BMR: Y
_____ = days of water fasting to use up stores
Or a slightly modified version, fast for some period 12 / 16 / 24 hours and add in some exercise. Walking is fine. It doesn’t need to be hardcore.
This is grossly oversimplified, but hang with me. That 110# female has a BMR of 1250 cal and gets 50cal per mile walked. The fastest way to deplete the estimated 1500 cal of circulating glucose is to fast for 24 hours and walk 5 miles. Done and done.
The 180# male has a BMR of 1850 cal. If he has 2000 cal of glucose circulating, fast for 24 hours and walk 1.5 miles. Done.