Blood ketones after meal, during fasting window and after training

(August) #1

Hi. This is my third time around doing the keto lifestyle, and ive incorporated intermitted fasting/time restricted eating into my routines. I usually have my first meal around 1800/6pm and finish eating around 2200/10pm. I typically have two moderately sized porkchops or equally sized beef slices together with a medium sized cauliflower, brussel sprouts or broccoli. I like to throw a carrot in there as well :slight_smile:
On the side I typically have high fat creme fraische (35% fat), and I might consume 100g of that.

My 2nd meal (which is my last) is typically a serving of home made yogurt (l.bacillus reuteri) with a tsp of low sugar strawberry jam (6g carbs per hundred). I might also have a small serving of cubed cheese.

I work out 3-5 times a week in a combination of cardio and strenght. My sessions typically are 15 minutes of cardio (target pulse 140-160), 45 minutes of strenght and another 15 minutes of cardio to end my session.

Ive been in keto since mid-august 2021, and lost about 17 kg so far.

So, I bought myself a blood ketone and blooodsugar measurement equipment. The test strips are quite expensive, but I wanted to measure my values throughout a typical day. My tests were conducted intermittently over a few days about 3 months into ketosis, and then during a single day I measured ketones and blood sugar values after I woke up in the morning, at noon, at 1400/2pm, at 1700/5pm (just before training), at 1900/7pm (just after training) and then 90 minutes after my meal.

I noticed the following:
My blood sugar is very stable, and all measurements were between 4.6 to 5.5. My blood ketones were surprisingly low compared to the urine keto-sticks I’ve been using so far (which all have been the darkest color): 0.4 - 2.5. I was quite surprised to learn that my lowest ketone levels were after my exercise (which was done fasted).

This is my question: From my understanding the body cant really use both carbs and ketones at the same time, in a way. So I guess that during exercise my body was drawing sugars from my muscles and liver, and therefore my ketone production went down (after exercising for about 1h15m, fasted). Can someone help shed some more light on the mechanics going on inside my body for this to happen? What happens if I utilize all my sugars and dont have any left. Will my body collapse?

I guess what happened to me is normal, but are there any dangers related to this? I mean, I would be more comfortable if my body would just keep making ketones and use them for fuel since there is no danger of me running out of fat stores in the near future (im still 97kg and around 24% body fat, so I have plenty of fuel stored haha). Or is that actually what happened - the reason I measured so low level of ketones after my exercise was that the body had already burned them?

Thanks a lot for your help on this!

#2

What you have described is normal, in terms of ketone readings. I suspect folks are often confused about this after Steve Phinney wrote that ketone levels increase with exercise. Certainly with strength/glycolytic activity, the opposite is the case. I can only infer he was talking about endurance activity. I personally have gone into workouts at 1.0 - 2.0 mmol and tested at 0.4 immediately afterwards. In fact, over time, trained individuals will find themselves continually in a more modest range (0.3 - 0.9) as they become more efficient at using ketones.

Your blood sugar is worth closer monitoring. I suspect your late night eating is contributing to the 4.6 to 5.5 morning readings (if that’s what you were relaying). And by 5pm, when you train, the readings should be lower - if you have been fasted c.18 hours.

(Bob M) #3

Your morning blood sugar may be higher.

image
image.jpg937Ă—625 125 KB

Or even better. Basically, the same exact curve from December 2017 to April 2019.

image
image.png734Ă—701 129 KB

(Bacon is a many-splendoured thing) #4

Or another possibility is that during your exercise your body was drawing ketones from your blood stream, and therefore the circulating level dropped a bit. Remember that blood ketone measurements reflect the gap between production and consumption, not the actual rate of production or rate of consumption.

(Bob M) #5

Which is one reason I think people like me (9 years LC/keto as of 1/1/22) tend to have (very) low ketones: our body matches input and output very well, leaving little “in transit”.

(August) #6

That thought is what I ended my post with - that the reason I measured lower ketones after training was because the body had burned what it needed, and not necessairly that it had switched to glucose burning.

You say “possibility”, but do we actually know what happens?

(Bacon is a many-splendoured thing) #7

Since there is no way to measure the rate of production of ketones in the liver, nor any way to measure which cells are using them, and how much, it is difficult to determine precisely what is going on. There is probably also a good deal of individual variation, as well, I would imagine.

Studies done by Phinney and Volek have shown that fat-adapted athletes burn fatty acids for their endurance performance, while explosive power is fueled from glycogen stores, whether in the individual muscles or in the liver. Muscle glycogen must be consumed in the muscle that created it, but liver glycogen can be shared at need throughout the body. While athletes new to a ketogenic diet report that their endurance performance returns much sooner than their explosive power, Volek’s team recently published a study showing that the glycogen stores of athletes who have been keto-adapted for two years or longer equal those of carb-burning athletes.

(August) #8

Thank you Paul. Do you happen to also know something about the rate at which we produce ketones and glycogen during exercise? Is it need-driven, or more of a fixed rate? How does the utilization of muscle and liver stored glycogen during more explosive exercise interfere with ketone production and utilization? Does the blood sugar rise when this happens?

Also, from what I understand of what you are saying, we dont really know if the reason for having lower ketones in the blood after strenght training is due to there simply being less excessive ketones available due to metabolism, or that the body got its energy from a different pathway (glycogen stored in muscles and liver)? Or do we know this? Is this what you were referring to when mentioning the study of Phinney and Volek - aka fat adapted WILL continue on the ketogenic pathway = the reason I’m low on blood ketones after training is that my body utilized most of it and therefore there is less excess in the blood to measure?

Finally, why do some here suggest that I pay more attention to my blood sugar. I dont believe that my morning blood sugar was the lowest I measured. 4.3 is the lowest, and it was just before exercise at 18.20 in the evening (fasted). Measured again at 20:18 after training it increased to 4.9 (fasted). My morning blood sugar that day was 5.1 measured at 08.37 (fasted, last meal 22ish the night before).

#9

That’s why I suggested it. That is on the high side, very likely influenced by the late night eating.

I think you’ve answered your own question, after several responses already.

#10

This is exactly the point made by Dr Paul Mason which, anecdotally, has been observed in other well-known long-term KD followers like Luis Villsenor (who floats around 0.4 upwards). That Phinney/Volek graph has a lot to answer for!

(August) #11

What do you consider normal range for blood sugar on keto, and what is your reference?

#12

4.0 to 5.4 fasted; up to 7.8 post prandial - Diabetes UK. The NHS states as low as 3.5 fasted is normal in non-diabetic population.

On keto, I think you should expect to be on the lower end especially post-prandial.

(Bacon is a many-splendoured thing) #13

The situation with fueling skeletal muscles is complicated. They seem to prefer fatty acids to ketones or glucose for most of their metabolic needs (a process called, variously, “physiological insulin resistance” and “adaptative glucose-sparing”). Dr. Phinney’s experience as a cyclist has been, he says, that a ketogenic diet makes him basically “bonk-proof.” There is, of course, a limit to how many calories we can pull from our fat stores in a day, but it’s fairly large (there are a number of posts by Richard about this, if you search the forums).

My guess would be that serum glucose would tend to rise in situations where explosive power was called for, as the liver releases glycogen to fuel the need, but that during a marathon, it would probably stay comparatively low. Fatty-acid metabolism is slower than glycolysis, which is why glucose is needed for explosive power, but it is more than adequate for endurance performance, as studies by Phinney and Volek have shown.