Is a high fat - low carb - moderate protein diet just as good for marathon runnner's as carb loading but still stinks for weight lifters, Crossfit and sprinting?
It is a nice discussion of the studies of carb loading versus keto and the apparent paradox. Also why keto fell out of favor.
Both observational and prospectively designed studies support the conclusion that submaximal endurance performance can be sustained despite the virtual exclusion of carbohydrate from the human diet. Clearly this result does not automatically follow the casual implementation of dietary carbohydrate restriction, however, as careful attention to time for keto-adaptation, mineral nutriture, and constraint of the daily protein dose is required. Contradictory results in the scientific literature can be explained by the lack of attention to these lessons learned (and for the most part now forgotten) by the cultures that traditionally lived by hunting. Therapeutic use of ketogenic diets should not require constraint of most forms of physical labor or recreational activity, with the one caveat that anaerobic (ie, weight lifting or sprint) performance is limited by the low muscle glycogen levels induced by a ketogenic diet, and this would strongly discourage its use under most conditions of competitive athletics.
Also is there no way to make up for the glycogen hit on keto or are you always going to torpedo your efforts if you are doing weight lifting and keto at the same time? (assuming i got that right...)
asked byMikeD (3641)
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on December 08, 2010
at 07:00 PM
Eva, I liked this paper (confused about the date of release, but the studies by the author (Phinney) were conducted in 1980 and 1983). You point out some of the good things that I also would have pointed out. First, that others who have tested athletic performance on low carb had done it incorrectly with respect to nutrients: if we are eating just meat and fat we should be getting sodium and potassium in broths. Don't just eat muscle meat, folks! Here's a good quote:
When meat is baked, roasted, or broiled; or when it is boiled but the broth discarded, potassium initially present in the meat is lost, making it more difficult to maintain potassium balance in the absence of fruits and vegetables.
But the other two points about how previous experiments on low-carb and performance have gotten it wrong are good also. That they have used either too much or too little protein. (The paper under discussion recommends 1.2-1.7 g/kg daily.) And that ketoadaptation can take up to two weeks. (All too often you see people say something like three or four days.)
But I think the biggest point, and what MikeD was trying to get at, was that while VO2max and endurance times did not change at all, the ability of the cyclists (the subjects in the second experiment) to sprint decreased:
The bicyclist subjects of this study noted a modest decline in their energy level while on training rides during the first week of the Inuit diet, after which subjective performance was reasonably restored except for their sprint capability, which remained constrained during the period of carbohydrate restriction.
Unfortunately, though, the paper does not give a quantified result for this, so we can only speculate about exactly what method was used to arrive at the conclusion. But the point is that moderate-high aerobic activity ("chronic cardio") and low-moderate aerobic activity ("move around a lot at a slow pace") are unimpaired in a ketogenic diet, but sprinting and weight training probably are, because those activities deplete glycogen so much and without carbs it takes longer to replenish the glycogen. (Note also that the cyclists in the second experiment got better and better at burning fat during their aerobic exercise instead of glucose/glycogen.) Anyhow this pretty much fits the experiments of a lot of VLCers, and I think we kind of knew it already. This research provides nice confirmation of it.
What does this mean for the big picture? Well, if you're hunting you might primarily need to "move around a lot at a slow pace" so it's good to know there will be no problem with that. But surely hunting might also require you to sprint every once in a while and to lift heavy things. So we could speculate for a while about these things. I think we already have.
[[EDIT:]] Wait, hold the phone. I found one of the earlier studies (university access), the second one. Here is the relevant passage I think.
There are indications in the results of this study that the price paid for such extreme conservation of carbohydrate during exercise appears to be a limitation on the intensity of exercise that can be performed. Although resting muscle glycogen and blood glucose levels were normal at EKD-4 [i.e., fourth week on the ketotic diet], at EKD-3 [third week] there was a marked attenuation of the RQ [respiratory quotient, which tells you how much glucose is being burned versus how much fat, I guess] value at VO2max, suggesting a severe restriction on the ability of subjects to do anaerobic work. This does not appear to be a function of differential accretion of glycogen by different fiber types, as the muscle biopsy specimens obtained before exercise showed the fast-twitch fibers to be qualitatively replete with glycogen at EKD-4. Thus, the controlling factor does not appear to be the presence or absence of substrate [i.e., glycogen] within the fiber. Rather, it is more likely a restriction on substrate mobilization or fiber recruitment. The result, in any case, is a throttling of function near VO2max, apparently by limitation of carbohydrate utilization. This appears to occur in exchange for a more ready use of fatty acids at moderate submaximal power levels, ie, at or below 65% of VO2max.
So it seems they didn't test sprinting ability directly, or if they did they didn't do it rigorously enough to put it in the official paper. But the basic idea, if I've understood correctly, is that when you go ketotic for enough weeks your body gets better at burning fat instead of glucose, in order to spare glycogen. This makes perfect sense. Additionally, and what is new to me, is the suggestion that the reason we're not as good at doing weightlifting or sprinting on a ketogenic diet is not that we deplete all of our glycogen and then can't get it back fast enough; rather it's that your body restricts glycogen "mobilization" or somehow otherwise restricts "recruitment" of the muscle fibers. And it seems to be some whole-body, systemic change that underlies both of these things: the improved ability with fat-burning in low-level aerobic exercise, and the lower ability with anaerobic exercise. The same thing that your body does to encourage the first hinders the second. So it's like a trade-off: you can go ketotic and get really good at using your fuel for aerobic stuff, but you sacrifice the other thing. That's kind of fascinating.
But I'm a novice at this and for all I know there have been a zillion studies since this one clarifying or disproving, but it's fun to learn about anyway.
on December 08, 2010
at 08:11 PM
Mamo Wolde won the 1968 Olympic Marathon in record time, at the age of 36. His diet was said to be composed of only meat and water.
on December 08, 2010
at 06:10 PM
I didn't seem to get what you got out of this research. The research studies showed no degradation in performance after time alloted for ketoadaptation and in the first study, there was improvement, probably due to (healthy) weight loss on the diet. The researchers then surmise that many probs found using other keto diets might be due to the fact that keto eaters are not paying heed to details like how the innuit drank blood and made a lot of bone broths and that just eating slabs of cooked muscle meat may in fact not be so healthy because of lack of potassium and salt. This is an important consideration for keto eaters, especially with the often quoted paleo doctrine to not add salt to food. The innuit consumed salt through brackish water and through blood. Are we doing that?
As for various types of exercise and various diets, I just didn't see any of that discussed much in the link. HOwever, my feeling is that marathon running and many of the very intense athletic events done professionally are simply not paleo. If someone were in a tribe and decided he/she wanted to spend 7 hours per day simply running around for no particular reason or continuously attempting to lift heavy things every day, for no apparent reason, to the point of exhaustion, then fellow tribe members would probably just assume this person was severely mentally damaged.
The body was simply not meant for that kind of thing and it takes a toll on longterm health, no matter how careful the diet and implimentation. Yes, I would not be surprised if it is possible to very carefully support such high levels of intense unnatural exercise using scientific means, but there will be consequences longterm on some parts of the body that when the body is continually being pushed and cajoled beyond its usual design performance. One might want to consider that activities that are well suited to the ketogenic diet or less carby diet may also be activities that are most natural for the human body to be participating in and activities not well suited to the ketogenic or less carby diet might be activities that are not natural nor even particularly good for long term health. I can't even count on two hands how many people I know that have permanent physical damage from just a few years of high school athletics, even though they did not go on to become pros. (football is a major offender)
on December 08, 2010
at 06:58 PM
The part about weightlifting requiring muscle glycogen seems to be an assumption tacked on the end. Unless I missed it, the study only looked at endurance exercise. This assumption may or may not have merit. People can certainly lift weights on standard ketogenic diets, it's not impossible. But their performance may be limited, and improve with targeted or cyclic addition of carbohydrate.