Glycogen is maintained and replenished during ketosis.
I was doing some reading and stumbled across this rather old, but very interesting paper. The idea is simple: they put rats on a ketogenic diet (surprisingly, real meat and vegetables) and had some train (running) and some not. Liver and muscle glycogen were examined before and after exercise (running). Here is the key for their abbreviations:
TE: Trained experimental. Ketogeneic, running program for previous week, running during experiment
TC: Trained control. Ketogenic, running program for previous week, not running during experiment
UE: Untrained experimental. Ketogenic, no running for previous week, running during experiment
UC: Untrained control. Ketogenic, no running program for previous week, not running during experiment
The block in the upper left corner shows the time where exercise is occurring. Everything after is recovery.
Figure 1 is ketone levels, 2 is liver glycogen and 3 is muscle glycogen. Clearly glycogen stores can be replenished during ketosis after exercise, and having been on an exercise regimen makes it happen for efficiently.
Last edited by The Scientist; 12-09-2012 at 05:16 AM.
I've been doing a ketogenic diet this winter as an experiment for me. When I started, I was so sore for about 10 days, I couldn't exercise. It gradually went away and now I'm lifting/sprinting as before. Prior to, my carbs were about 100-200g/day, now 25g or less.
What should our takeaway from the study you linked be?
To me it says that maintaining some level of glycogen is important, otherwise these animals would not be going through gluconeogenesis to keep levels up. The second is that the ability to do this is flexible, and exercise "programs" the body to ramp up glycogen production when in ketosis. This says that glycogen during exercise is especially important. Lastly, it eases my concerns about keeping up a heavy lifting routine while in ketosis, which I plan to try out starting this week.
Is perpetual gluconeogenesis very stressful to the body (and mind) in the long-term?
That question has never been specifically tested experimentally. Since carbohydrate restriction (ketosis) is the only time humans ever really go through continued gluconeogenesis, I think we can safely apply any information about long-term ketosis to long-term gluconeogenesis. This (long-term ketosis) has also never been looked at in a controlled experiment, but entire cultures (e.g., Inuit) did just fine on it, so I don't think there is reason to worry.
Originally Posted by j3nn
I guess the question that many want answered is if ketosis is optimal or just useful under certain circumstances? We know the body prefers glucose and will make it in its absence, which tells us how important it is. But if it creates it in near equilibrium, could it be possible that either way is "optimal"?
You mean one culture did it but i dont know about fine. I believe they showed major signs of early aging.
Originally Posted by The Scientist
Also i dont know how much but there is a bit of carbs from fresh liver and muscle meat.
I would only strongly recommend ketosis for someone looking to loose a lot of weight. Beyond that, there is really no evidence speaking to its long-term benefits for any application (other than childhood epilepsy). I am trying it out to see if I can lose a stubborn 10 lbs that I have never been able to get rid of. I think everyone jsut needs to run an experiment for themselves.
Originally Posted by j3nn
I'm not sure if you mean "early aging" to say that their skin/faces look worn and old, or something else. It seems like this might be the extreme temperatures they lived with, but I don't have hard evidence to back that up.
Originally Posted by Zach
The glucose content in meat/liver is negligible.