Low blood keton levels

[SomeGuy]

These exogenous ketones always make me laugh… I ingest exogenous ketones, I have ketone bodies in my system, I am therefore ketogenic. Eeeeerrrrrrr… no. You are ketogenic when you burn primarily fat for fuel. The existence of ketone bodies in the system means nothing at all.

Indeed. If I eat exogenous celery, I have celery in my system. My body has still not produced any celery.

I am not celerogenic.

[Alecmcq]

I am not celerogenic

I must be baconogenic!

[PaulL]

Ketones are a by-product of fat metabolism.

While you could say this in casual speech, it would be more precise to call ketone bodies “intermediate products” of fatty-acid metabolism (or “intermediate metabolites,” for short), since they are not left over after a fatty acid is reduced to water and carbon dioxide, but are rather produced during the process and then consumed as the process continues. It’s very similar to how charcoal is produced during wood-burning, but is immediately consumed as the fire progresses.

In both cases, of course, the intermediate products have their uses, so sometimes we produce ketone bodies—or charcoal—to be used later, and don’t continue past the point where they are produced. But I see that as being different, somehow, from a “by-product.”

Please forgive me if I am being too fussy with all this. It’s just that the distinction between colloquial usage and precise technical language has come up in another thread, and I am sensitive about it at the moment. And the overall point of your post is dead on, so this quibble is not a criticism of that point.

[PaulL]

What am I doing wrong?

Probably nothing. For one thing, the technical definition of “nutritional ketosis” refers to a certain amount of β-hydroxybutyrate in the blood stream, whereas the breath meters measure acetone, and the urine strips measure acetoacetate. So it is possible that your serum β-hydroxybutyrate might be at a level that meets the definition of nutritional ketosis, but not very much acetone is making it into your breath.

But all three ketone bodies occur in blood, breath, and urine, and I’ve never heard anyone talk about how the values of all three ketone bodies in all three locations correlate with one another. For one thing, acetoacetate and acetone are easily interconverted, so there’s that to contend with. There is apparently a relationship between how much acetoacetate and how much β-hydroxybutyrate are produced during ketogenesis, but I haven’t really seen it discussed anywhere.

For another thing, as @SomeGuy points out in the post immediately before yours, if we are eating low-carb and are still alive, we have to be in ketosis. If we are not flooding our blood stream with glucose from our carbohydrate intake, a hormone called glucagon is produced in the pancreas, which stimulates the liver to produce what small amount of glucose we actually need (gluconeogenesis) and enough ketone bodies (ketogenesis) to fuel the other needs of the body. The brain and the heart muscle, in particular, do very well on ketones, whereas the red blood corpuscles (erythrocytes) lack mitochondria and therefore require glucose for their survival. And the skeletal muscles actually prefer fatty acids over ketones or glucose.

Athletic performance is a trickier topic … depending whether your primary activities entail sprint-like bursts of energy, or longer-term endurance/marathon activities.

Endurance can be better-fueled by fatty acids than by glucose, but the muscles need some time to heal their mitochondria and to reactivate certain other pathways that get shut down if high carb intake goes on for too long. This process of healing and reactivation is called “fat-adaptation” or “keto-adaptation,” and it generally takes close to two months in most people. During that time, endurance suffers. Explosive performance requires glucose, since fatty-acid metabolism is a slower process, even though it yields more ATP in the end and, with the drop in glycogen stores resulting from cutting carbohydrate intake, explosive performance also suffers after we embark on a ketogenic diet.

The experience of most athletes who embark on a ketogenic diet is that endurance returns quite a while before explosive power does. However, the team headed by Jeff Volek at Ohio State University has recently published a study showing that, by the two-year mark, the glycogen levels of keto-adapted athletes are indistinguishable from those of carb-burning athletes, so explosive power does indeed return, and at some point before the two-year mark.

[SomeGuy]

@PaulL Yes, all this. But this explanation will cut into Phinney/Volek book sales.

[amwassil]

Thanks. I sometimes tend to drift between casual and technical descriptions. I certainly did not mean to imply that ketones just get sloughed off uselessly.

[PaulL]

No worries. My post was more to keep the record straight for newcomers lacking the background.

[Shortstuff]

it seems Im not able to get into nutritional ketosis, just fat adaptation

Fat adaptation is not possible without being in ketosis, stop chasing pointless numbers.