Hi there, I realized that anytime I do some exercise, my blood ketones levels go through the roof.
Here‘s the last example:
I have observed this again and again. Has anyone seen the same effects and can explain it?
multiple causes… my blood ketones are usually lower in the morning anyway I’m guessing due to the dawn phenomenon pushing my blood sugars higher so lowering ketone levels as my body gets flooded with glucose to get me out of bed.
If I’m fasted my ketones go a lot higher… were you fasted on the hike? And I guess your blood sugar would have been depleted after the hike.
Exercise inhibits insulin production so your body can access energy. You might also notice a temporary increase in glucose at the same time - nothing to worry about. I wouldn’t say 1.1 was through the roof in absolute terms, but a huge change from 0.1. 
Thanks for both your answers! You might be right. A combination of IF and sport would probably be the reason for this tenfold increase. And I’m not worried, just very interested 
Are you keeping carbs <20g / day. 0.1 is not generally considered in ketosis. Are are you just not yet fat adapted? I don’t notice much change in ketones post exercise but I have been fat adapted for many months. Mine runs 0.6 to 1.2 most days unless I’m fasted then the longer the fast the higher the ketones.
I’ve been fat adapted for more than a year now.
My readings used to be > 1.0 for the first 6 months, and then it slowly decreased. Nowadays I have a hard time getting them up unless I fast or exercise.
My carbs and proteins are in check and I still feel completely in Ketosis: no hunger or cravings, high energy, no nap or need for coffee…
That’s what I’m trying to understand.
Everyone is different - my blood ketone levels move around much more due to any fasting I am doing, I haven’t noticed much of a correlation due to exercise (didn’t specifically look for it though).
But, given your certainty that you are (and have been for a long time) fat adapted, my theory would be simply that your body has become very efficient - at rest - producing just about the amount of ketones it needs. So, your brain is mopping up nearly all produced ketones and your blood measurements look low.
I think the fact that you are seeing any ketones is what is important - along with the fact that with exercise, ketone production goes up - obviously much faster than can be used.
Interesting hypothesis. Any creative idea how I could validate or invalidate it?
@RobC is bang on! And you have already validated it for yourself. Your baseline is .1 give/take and then output goes up 10-fold to meet the additional energy requirements imposed by exercise. This is an amazingly dynamic and energetic system that constantly works to maintain homeostasis: matching synthesized fuel to current demand for fuel. It’s also a very ‘noisy’ system in the sense that individual measurements of any of it’s markers can be all over the place even for a short span of time. For example, I measure BrAce with a Ketonix multiples times per day and the individual breath samples are very noisy. But graphing the individual results to a moving average puts it into perspective very well. It’s beautiful.
Amazing experiment:
So it really seems to confirm this theory: fasting and effort (even though it was not really aerobic) both seem to triggers the production of ketones in my body.
As for the baseline. It seems to be there, even if the readings are low. It then allows my body to create ketones quickly when needed. And stays otherwise at an efficient minimum.
Thanks for all your input!
Don’t tell anyone about this. People here are convinced protein dramatically reduces ketones.
I workout in the morning and get a pretty good rise in ketones and typically a rise in blood sugar. But I’m only working out an hour (35 minutes weights, rest of time HIIT on the Dreadmill).
When I was wearing my CGM, things like working around the house would cause my blood sugar to stay high until I stopped working. It’s just your body’s way of having enough of what it needs for energy.
Also, you probably lost water from your blood, so your high ketones were perhaps just more concentrated.
I suspect that this started as part of the speculation that excess protein always got turned into glucose in the liver, because of gluconeogenesis. Now that we know that gluconeogenesis is driven by demand, I expect the protein-lowers-ketones idea to go away. I suspect that the real issue is what glucagon is doing at the time the extra protein is eaten, but that is also simply speculation.
Do you know what the mechanism would be, @carolT? I can’t think of one, off the top of my head.
P.S.
I also think that different people are going to have different glucagon : insulin ratios, even in ketosis. So someone imbalanced to the insulin predominant side of the equation will have the most sensitivity to the effect. Not that I have any data for this but I hope Bikman-Feldman collaboration will come up with some.