Saturday, March 12

Quick on starch, ketosis and non-oxidative glucose disposal

Post-exercise ketosis is a phenomenon rarely discussed these days. But there is some considerable number of research done on this subject. A very interesting study done in the 80's tested the effects of alanine, glucose and starch ingestion on starvation ketosis and post-exercise ketosis (1).
"The effect on the blood ketone body concentration of a 100 g oral dose of either alanine, glucose or starch was studied in forty-four healthy men. Twenty of the subjects were highly trained long-distance runners who underwent 'glycogen stripping' as previously described by us (Koeslag et al. 1980). Twelve non-athletic subjects fasted for 65 h before the test, and twelve were studied on a normal day after a normal breakfast."
Trained athletes were tested after running 2 hours. They ate a low carbohydrate diet for 48h prior to the experiment. The starvation group was composed of 12 non trained subjects, fasted for 65 hours. 

Results

The arrow shows the point in which the different solutions were ingested.
"The ingestion of glucose or alanine after exercise caused the mean blood ketone body concentration to fall to less than 0 5 mmol/l in 2 h. The fall was more prompt, less variable and longer lasting after 100 g alanine was ingested than after 100 g glucose. At 15.00 the mean blood ketone body concentration was rising again in the subjects who had taken glucose, but not in those who had taken alanine. The difference between the mean blood ketone body concentrations of the two groups at 15.00 is statistically significant (P < 0-01).
(...) Starch ingestion caused the blood ketone body concentrations to fall, but to a lesser extent than after alanine or glucose ingestion. After starch ingestion, as after glucose, the mean blood ketone body concentration was rising again at 16.00 (Fig. 1), thus reaffirming the evanescence ofthe antiketogenic effects of carbohydrate administration."
So the antiketogenic effect was alanine > glucose > starch. We are talking about 100g of each, after either 65h of fasting (almost 3 days) and running 22km plus a low carbohydrate diet. This is by no means a "typical" scenario. But it shows us that starch is less antiketogenic than glucose. Evolutionary reasons perhaps? 

Extrapolating the findings to real life situations, there shouldnt be much of a problem about getting back to ketosis consuming carbohydrates only post workout, specially if you follow a very low carbohydrate diet, fast daily and train in a fasted state. This is the winning combo for minimizing glucose oxidation and maximizing non-oxidative glucose disposal after a glucose load. 

Studies have shown that adaptation to a high fat-low carbohydrate diet produces a shift in glucose metabolism, reducing glucose oxidation and increasing glycogen synthesis and glucose storage. A similar metabolic response is triggered by short term fasting and resistance training. 

Further reading on high fat diets and glucose metabolism:





ResearchBlogging.orgKoeslag JH, Noakes TD, & Sloan AW (1982). The effects of alanine, glucose and starch ingestion on the ketosis produced by exercise and by starvation. The Journal of physiology, 325, 363-76 PMID: 7050344

8 comments:

  1. Great post Lucas.What are your thoughts on doing the carbs preWorkout instead.Today I ate just meat all day until I hit the gym.Before I got to the gym I purchased a ready to drink PWO shake that has 30gms whey and 40gms carbs(mostly maltodextrin).It also has 100mgs caffeine and I must say I had a great workout drinking that with alot of water during the workout.

    What I am guessing is that the muscles you start pumping blood into get the good flow of carbs and whey when you need them most.Could be that the test results would of been even better if they took the carbs pre-workout instead....that is getting back into ketosis as quickly as possible.Then again a high protein diet is supposed to keep you out of ketosis from gluconeogenesis.What do you think?

  2. Wolfstriked,

    My guess is that yes, you should get into ketosis sooner eating carbohydrates before/during workout. But I think you miss the benefits of training in a fasted/carbohydrate restricted state. Research has shown that training in this scenario enhances the cellular responses triggered by exercise, for example, increasing glycogen resynthesis 3 to 3.5 fold compared to the fed state. As long as you train infrequently, dont overeat carbohydrates and follow a mostly fat/protein diet combined with periods of fasting, you should only get out of ketosis transiently for a couple of hours. Remember that the benefits of training (and why it stimulates muscle hypertrophy) are due to damage/adaptation. There is nothing wrong with getting out of ketosis transiently, either.

    Re: High protein & ketosis, read one of my posts on the subject for more info.

  3. I read the high protein and ketosis post.I agree and always thought to myself that you must be in ketosis on a high protein diet.No incoming carbs and your brain is functioning=ketosis IMO.When I first start low carb diets I am a zombie for two to three days.Then my brain functions better than normal once I am actually in ketosis.

    What do you think of higher protein speeding up the metabolism?I feel amped when I go higher protein and feel its more than just stable BSI found these two studies,I am pretty sure there are more as these two took me a minute to find.

    http://www.drhoffman.com/page.cfm/607

    http://www.wellnessresources.com/studies/high_protein_diets_improve_your_brains_leptin_function/

  4. Yes, high protein produces high thermogenesis and hence an increase in energy expenditure.

  5. malpaz

    how do you explain a high protein diet with high post meal BS levels, even with ample saturated fat? would this inhibit the favorable glucose metabolism one aims for with a ketogenic diet.

    basically, if the aim of the ketogenic diet is to run off fatty acids, what if the body refuses to do so by elevating insulin, storing fat and spiking BS post meal. this is all in the presence of plent of fat for a FA energy conversion but it isnt happening.

  6. Malpaz,

    Im not sure if Im following but high BS can occur despite a very low carbohydrate intake via insulin resistance.

  7. Hi Lucas!

    Would you write more about sport and ketosis?

  8. Hi Edo,

    Not my area of expertise but I can write something on sports and ketosis when I have some time.