First off i think its quite awesome that you take the time to try and research claims. My hats off to you, sir.

Second, like francois said, try more generic search terms. Here is something anyone, like myself, without access to pubmed can do:

Google " low carbohydrate diet retard growth" and click on scholarly articles. Its been demonstrated in both human and nonhuman animals.

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who's smarter than you're? i'm!

Peddle: to sell.
Pedal: to ride [a bike].

Ben has been accused of riding a power bracelet. This, of course, casts aspersions on his credibility.

Francois aint from around these here parts.

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who's smarter than you're? i'm!

That is not a spelling error. That is a grammatical error. Fail x2.

John

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Top notch coaching: Francois and Accelerate3 | Follow on Twitter: LifetimeAthlete |

I know peddle and pedal. I thought he was referring to pedaling vs pedalling. Both are correct.

I actually thought it was a (nice) pun given how Ben pedals around his products ;)

Unless he thought that was the correct spelling of the cotrect word. ;-)

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who's smarter than you're? i'm!

I'm at the end of a biochemistry class - and I happened to take a test yesterday that included ketogenisis - so this thread is pretty interesting to me. For those of you who don't know, the main focus of Biochemistry are metabolic pathways. We either synthesize biomolecules or we break them down (catabolism). The purpose of synthesis is usually to store energy and the purpose of catabolism is usually to create energy that can be used by our body.

My main take-away from this class is that there are efficient ways for our body to do all these processes and inefficient ways for our body to do these processes. Given a choice the most efficient processes take over. That's why it's important to have a lot of glycogen stored before a big race - because otherwise you have to switch over to fat breakdown - which is less efficient. That's what happens when we hit "the wall" - our body has no choice but to rely on these much less efficient metabolic pathways to supply energy to our muscles.

Ketogenesis only happens when we have a lot of Acetyl-CoA left over from the Citric Acid Cycle. The only reason we would have a large amount of Acetyl-CoA is that we don't have the proper intermediates to continue the citric acid cycle. This usually only occurs in starvation or uncontrolled diabetes. If your body is actually using Ketone bodies (one of which is acetone) for fuel you are in a bad place. If you have too many ketone bodies in your system the pH will go down and you may experience ketosis, which can lead to coma or death. One test for ketosis is to smell someone's breath - if it smells like acetone (nail polish remover) it's probably time for them to go to the hospital.

Most of people on this thread who seem to have had success with the "Ketogenic Diet" talk about losing 50-100 pounds. I guess you guys want to force your body to use inefficient metabolic pathways because that will help you lose weight. But, for people who are at a normal weight this seems like a really stupid plan if you want better athletic performance. In order to have the best performance you want your body to use the most efficient processes possible. That means having a decent amount of glycogen - which means you need to eat carbs. I agree that you don't need to eat a bunch of refined sugar (again because that can mess with how your body regulates these metabolic processes - and might lead to carrying extra fat) - but to purposely make your body do something that's very unnatural (produce ketone bodies) seems like it's not worth the risk. Even if you don't experience ketosis - you may be permenantly changing how your body regulates your metabolism (hormone signals from insulin and glucagon) - furthermore, not all tissues can even use ketone bodies for energy (e.g. the liver) - so, you might be doing damage to those organs if you are relying on ketone bodies for energy.

I read a quote somewhere...if you really want to learn about nutrition, talk to a biochemist. I'd like to think that is pretty true.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

Just a little clarification: ketoacidosis, which is what you are describing above is a life threatening condition that occurs in diabetics (type 1 mainly) due to the near absence of insulin. People on the ketogenic diet are not going to get into a state of ketoacidosis. Ketosis is a state where the body has started using ketones as a source of energy (carbohydrates are still present, they just aren't meeting the full metabolic needs of the body).

Without biochemistry, we would have no idea whats actually happening in there.

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who's smarter than you're? i'm!

I read this entire thread and no one recommended the Primal Blueprint Cookbook. Written by 2 successful triathletes (retired). Very sensible potentially ketogenic diet in my opinion.

I'm constantly amazed that people believe the laws of physics don't apply to our bodily functions.

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Don Larkin
Reach For More
http://www.reachformore.fit/
USAT Lvl1 Coach, NSCA-CPT, NASM-CPT, BS Exercise Science

Unfortunately its not just related to bodily functions. too many people are too quick to discount every branch of science.

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who's smarter than you're? i'm!

Calories in, calories out is oversimplified and is almost impossible for many to adhere to long term. It is also important to note that exercise and diet are not mutually exclusive in terms of appetite. I trained a lot more than ever this year but I also ate a lot more than in the past. Exercise creates hunger.

Genetics play a huge role in which diet works best for an individual. The health authorities suggest a diet high in carbs but obesity is at an all time high and it is not due to folks being lazy. Overeating carbs makes you run high insulin levels and can lead to insulin resistance. Trigs also run very high in folks who have diets high in carbs.

I have friends that are vegans and it has transformed them, I have a friend who does Paleo and he is about the most in shape guy I know. There is no one size fits all here. I would say that eating very little to no carbs would be difficult for an endurance athlete but may work for non athletes.

I speak with Endos on an almost daily basis. Why do you think that type 2 diabetics need to carb count? This doesn't mean going ketogenic is the solution but calories in, calories out is not the only answer.

Regardless of all that, consume more calories than you burn and gain weight, or consume fewer calories than you burn and lose weight.

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Don Larkin
Reach For More
http://www.reachformore.fit/
USAT Lvl1 Coach, NSCA-CPT, NASM-CPT, BS Exercise Science

It is absolutely the only way to lose weight outside of surgery. Regardless of genetics or willpower, it is the only answer.

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who's smarter than you're? i'm!

Isn't this statement really putting the conclusion before the data? Isn't the whole purpose of science to break through our preconceived notions of truth (or what is natural) and determine based on data what is fact and then draw conclusions from the data rather that interpret the data to support a particular conclusion?

Part of the data in Phinney's NK performance book shows endurance cyclists greatly improving the efficiency with which they were able to oxidize fatty acids. Two of the participants in one of the studies cited in the book were adapted to burning 2 grams of fat per minute. At 100 grams per hour that's 900 kcal per hour. That is huge and would go a long way to sparing an athlete's coveted glycogen stores.

I think it is a perfectly reasonable hypothesis to suggest that the body can adapt to and become more efficient at oxidizing fat in the same way that the body adapts to aerobic exercise to create greater aerobic capacity. I'm not saying its safe or effective or even a good idea. I am saying it is worth a good empirical look.

After all, science is not a Stevens of the truth about our world. It is just a snapshot of what we think we know based on what we can observe. The most basic principle of science is "prove me wrong." in fact, science is a continuing cycle of really smart people of good faith being proven wrong. Most honest scientists, especially epidemiologists, will readily admit that one should take all their data with a grain of salt. One of the purposes for publication is to give others an opportunity to test the hypothesis and the methods. Remember that these guys are the ones that brought you HFCS, margarine and trans fat.

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Panabax

We’ve heard that a million monkeys at a million keyboards could produce the complete works of Shakespeare; now, thanks to the Internet, we know that is not true.—Robert Wilensky

Isn't an endurance athlete's ability to oxidize fats at a higher percentage of their max output what aerobic fitness really comes down to?

I mean that's what our body works to achieve via stimulus through endurance training. It's not like elite athletes store materially different amounts of glycogen than the average athlete (please do correct me if I'm wrong on this one), so fat metabolism rates are the real kicker in determining the speed we can do these races at.

If you were trying to suggest something else, then please rephrase.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

I guess my point was that fat oxidation is not the only adaptation that is taking place with aerobic training. Aerobic capacity is necessarily the ability to oxidize something, but the limiting factor in any given individual may or may not be the ability to mobilize fuel from our stores. In other words, I started in 2011 from an untrained state. My aerobic exercise increased the size and stroke of my heart and the thickness of my LV. I am sure that there are many more capillary blood vessels in my legs so that the oxygen coming into my lungs can be delivered to my muscles more efficiently. I am certain I have more slow twitch muscle fiber in my legs than I did which further increases my ability to oxidize fuel. The body adapts to all types of stress by making adaptations. My point was maybe training the body in the absence of carbs will cause adaptations to increase the efficiency with which fat is mobilized so that higher outputs can be achieved without glucose as a fuel source. Previously, I was working on the assumption that I could only go "so" fast on fat and to go any faster required more glucose per mile. I think that premise is worth proving or disproving. Right now I am running about as fast as I ever had and I haven't eaten any substantial carbs for over two weeks. Last weekend, however, sucked a$$. Now, with the understanding that most of you probably warm up faster than I run flat out, the switch to fat as a primary fuel source does not seem to be effecting my performance now (it did last weekend for sure). Wouldn't it be nice not to eat all that damn GU in an Ironman race?

I think the general consensus is that fat metabolism is not the key to going fast. Rather, it is training, speed work, VO2 Max natural ability, and so forth. It is part of the key to going long, but the real "trick" as I understood it was to burn enough fat so you could take on enough carbs to finish an IM distance race with some carbs left. It it were not for the fact that there is a limit to how much sugar you can digest, fat would not enter the equation at all for the current prevailing mind set, or so it seems.

Hell, what do I know. I'm not claiming to know anything. I just think science works both ways and the fact that data support one conclusion do not mean that that same data precludes some other seemingly contrary conclusion. You have to test the contrary conclusion in the same way you tested the primary conclusion.

But hell, I like running today. That is a gift.

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Panabax

We’ve heard that a million monkeys at a million keyboards could produce the complete works of Shakespeare; now, thanks to the Internet, we know that is not true.—Robert Wilensky

I would like to think it is true as well but it just doesn't always work that way. Biochemists tend to be rather granular folks. This is great for developing a thorough understanding of a limited number of processes. Unfortunately, our bodies are not a limited number of processes and it becomes easy to miss the forest for the trees. The theory behind jejunoileal bypass, for instance, was pretty solid even though the reality was increased morbidity.

Things which "work" in theory biochemically don't always actually work in practice. This is why I tend to trust actual trials with actual humans. Unfortunately, the funding just isn't there for most of these sorts of trials and so we end up with small n's and crappy sample designs whose results can be argued over.

Still, it is often the best we have. I tend to trust in my inability to understand at a theoretical/biochemical level how something will actually impact overall health.

Hey Panabax,

Hopefully I didn't come across wrong, but I really think you're chasing a red herring.

Have a read of this 3 part series on running economy (it's good stuff!):

http://www.sportsscientists.com/...-economy-part-i.html
http://www.sportsscientists.com/2007/12/running-economy-part-ii.html
http://www.sportsscientists.com/2007/12/running-economy-part-iii.html

A lot of the training terms you elucidate are going to reduce to the two most important energy terms we *really* care about in endurance sports (ESPECIALLY ultra-distance events like an Ironman). Please note this isn't definitive, but more a first-order approximation. (Nor do I assume to know how to train these factors)

- Economy (amount of energy required to move X distance), which tends to include how "well" you move at a certain velocity (swim stroke, aero on the bike, minimal excess movement while running). I don't think there's a HUGE difference

- Fat oxidation rates, which includes effects like sustainable cardiovascular output, vasculature in the muscle, mitochondrial density, etc.

Both terms are the sum/product of multiple factors.

Improved economy lowers the total amount of energy we need to get across the finish line.

At a given glycogen reserve, the higher our fat oxidation rate, the more total energy we can burn per minute.

In short--we're saying the same thing :)

I don't think you're going to get any material training benefit from eating a low carb diet. Your body is *maybe* getting better at gluconeogenesis (and the preceding pathway to get there from fats) at a rate quicker than you would under a balanced diet, but I kind of doubt it. I'm pretty sure your workouts are tapping into your established glycogen supplies, which just means you're hampering your ability to recover from a workout, which will swamp out any other marginal training effect.

Unless you're wiling to go *very* slowly, there's no good way to avoid eating carbohydrates during an ironman. To a zeroth order, the person who can burn the most calories per kg body weight will winn, which means using every possible mechanism our body has in place. :)

Hope the run went well and your training continues to improve.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

See EF Coyle in pubmed...lots of good stuff.

:) I was trying to avoid linking all that literature in. I probably failed in simplifying my description by too much.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

I will review the articles you cited. Thanks for that. I'm in my last couple days of taper before my marathon on Sunday. My training runs are back to where they were while I was eating a more conventional diet. I have already decided to take on 100 kcal every 5 miles on the run, so I won't generate much useable data as a result of my performance - unless I bonk anyway from depleted glycogen levels.


So, for me, the interesting question is can I influence my fat oxidation rate at any given output merely by restricting carbs and existing in a ketogenic state, holding everything else constant. If so, that might be good to know.

Thanks again.

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Panabax

We’ve heard that a million monkeys at a million keyboards could produce the complete works of Shakespeare; now, thanks to the Internet, we know that is not true.—Robert Wilensky

This is also a very important set of distinctions to make when discussing these diets. A low carb diet isn't necessarily the same as a ketogenic diet used for treating epilepsy (and usually they're very very different). The classic ketogenic diet has a ratio of fats to carbs+protein of 4:1 or even higher. Many of the diets I've seen called "ketogenic diets" do not come close to that.

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Yeah, it's a great bike but the engine needs work.