The low carb high fat debate

[waimata]

Unfortunately I suspect they did not stick with it for long enough to really find out if it could benefit rowing. Majority pulled out around week 3 and I think it was pulled by week 6. I guess 6 weeks of sub standard training is too significant. Do not know for sure - second hand information. The protocol involved having them "carb up" for race day, and be in ketosis for training, although I'm not sure what sort of timeline.

I had read a study (sorry, I'm going to be that annoying person and not source right now) where they had done something similar to try to maximise both fat oxidation and carb pathways but in the end the muscle's response was more either-or to which fuel. So the period of fat adaptation had blunted the muscle's ability to use carbs, and high intensity performance dropped. Given that rowing training is such a mix of intensities I'm not surprised that everyone dropped out, but would have been interesting to see the study run its course!

[Stelph]

That's a shame, the books that I've read do suggest that it takes several weeks for the body to switch to using keto, it sounds like a lot of the rowers didn't give this enough time to properly test tho I can understand if they were somewhat sceptical of having such a low amount of carbs in their diet

Also I'm surprised that the study had carb loading before pieces/tests were done, again the bed ive read suggests that you shouldn't need to load carbs befor pieces, infact doing so completely undermines the body's switch to keto as far as I understand

[waimata]

I think the addition of carbs for races (though this never got to be tested due to the study being pulled) was to try to adapt the diet to utilise carbs for the high intensity rowing race while using ketosis for the lower intensity training to try to optimise both pathways. But this is just guessing.. A shame it couldn't run its full course but not surprised, must happen a lot in studies on trained athletes.

[bloomp]

Bloomp -- Thanks for the helpful articles. Do you (or your prof) know of longer-term studies?

Sorry to drag this up, but a much longer-term study came out a few months back. I spent a few semesters working on it, so feel free to ask questions. Several other data sets from the study will be published over the coming year.

http://journals.plos.org/plosone/articl ... ne.0113605

Somewhat related n=1, I have been training on low-carb for the past six months. I have no issues hitting top end speed (mostly triathlon training, working back into the single now) on run and bike intervals. As time was limited with grad school and teaching, I would do 2-3 interval run sessions and 1-2 interval bike session weekly with a long run and swim. 800m repeats (6-8 reps) were common and done below 6:00 pace with 1-2 minutes rest. I was doing distance (6+mi) runs (<2mmol/L) at 8:20-8:30 pace. I also had a running and cycling VO2 max test done in this time - maxed out at 60mL/kg on the run with my RER barely cracking 1.0 at the end of the test, and 55mL/kg on the bike with RER never going above 1.0. World-class? No, but I also was spending fewer than ten hours/week training.

I will report back once I really ramp up the rowing training, but I really don't foresee any issues. Is it difficult to keto-adapt while training hard? Yes, absolutely. But it's entirely possible. And I'd rather eat a pound of bacon than a bowl of pasta.

[SDsweep]

The problem with going full-on keto is demonstrated in this chart: https://twitter.com/TStellingwerff/stat ... 9045267458

No matter how well adapted the body is to it, you simply can't produce enough energy for top-level performance in shorter events like rowing 2k by using only fat.

This brings up one of the other common problems when people talk about LCHF diets, which is that they aren't clearly defined. Can a rower put up big numbers while on a diet that is lower carb? Probably, sure. You aren't using that much glycogen in 6 minutes anyway. But to do it by trying to only utilize fat simply isn't going to happen. So a diet that is 50/30/20 carbs/fat/protein rather than the 60-70% carbs that is normally recommended could very well work, and I'd argue that it's probably better for you in nonperformance related ways. But when people try to go REALLY low carb, it's a problem for an event as short in duration as rowing is.

Trent Stellingwerff, the guy whose tweet I linked to above, talks a lot about periodizing one's nutrition. I think this probably makes the most sense. More carbohydrate is consumed when the athlete is working at higher intensities and less is consumed when the bulk of the work is SS. This can be organized into macrocycles along with the athlete's training or handled on a day-to-day basis.

[bloomp]

The problem with going full-on keto is demonstrated in this chart: https://twitter.com/TStellingwerff/stat ... 9045267458

No matter how well adapted the body is to it, you simply can't produce enough energy for top-level performance in shorter events like rowing 2k by using only fat.

This brings up one of the other common problems when people talk about LCHF diets, which is that they aren't clearly defined. Can a rower put up big numbers while on a diet that is lower carb? Probably, sure. You aren't using that much glycogen in 6 minutes anyway. But to do it by trying to only utilize fat simply isn't going to happen. So a diet that is 50/30/20 carbs/fat/protein rather than the 60-70% carbs that is normally recommended could very well work, and I'd argue that it's probably better for you in nonperformance related ways. But when people try to go REALLY low carb, it's a problem for an event as short in duration as rowing is.

Trent Stellingwerff, the guy whose tweet I linked to above, talks a lot about periodizing one's nutrition. I think this probably makes the most sense. More carbohydrate is consumed when the athlete is working at higher intensities and less is consumed when the bulk of the work is SS. This can be organized into macrocycles along with the athlete's training or handled on a day-to-day basis.

So I, for one, did not say that everyone should be keto-adapting for training. I am merely reporting on what has been working for me and it happens to tie into the subject at hand. I am very familiar with the science behind metabolism - I quite literally just finished a masters in exercise science with Dr. Ed Coyle. You want to talk metabolism, I'm game. And the biochemistry behind what I am doing is well-founded. It's just unfortunate that not many studies have been properly executed in the realm of keto-adapted athletes.

I think that nutrition should be very individualized and athlete-based. A blanket percentage recommendation is useless on a case-by-case basis. For me, I likely have some genetic/basal level of insulin resistance so cutting out the carbohydrates even while training hard is much better for my health. Look at Peter Attia - incredibly fit but he had terrible blood measurements while eating the SAD. He switched to low-carb, performs better, loses weight and improves his blood measurements.

I am looking at my VO2 max test now - again, this was on less than 10 hours/week training. I am at an RER of .85 at 90% of my VO2 max. I'm sure that endurance athletes that can and do train significantly more than me would have a much greater lactate threshold and thus be able to maintain even closer to VO2 max at a similar RER or lower. You absolutely can put up the big power numbers that rowers need without high carbohydrate intake - in fact, because you are sparing so much glycogen, you likely have more available at any given time than someone who is reliant on carbohydrate at any exercise intensity.

The lab that put out the study I just linked to has another publication coming out that looks at keto-adapted athletes and performance. They released some preliminary results on inflammation markers, but it's quite literally the first study to compare high-carb and well-adapted low-carb athletes on performance measures. These are distance runners that have been keto-adapted on their own accord, not folks that volunteered for a dietary intervention. As soon as the study is out, I'll be happy to share it.

Anyhow - I will report back after club nationals and Canley with how things go.

[SDsweep]

As I was looking for a link to the Volek study to post in response to this, I came across an article that explains the point I was trying to make better than I could have. I'm just going to post the link here: http://www.runnersworld.com/sweat-scien ... at-as-fuel

The issue is that even fat-adapted athletes can't burn as many total calories per minute. So even though they were able to burn more fat per minute than the non-fat-adapted athletes, they were still producing less overall energy. Again, the curve of the graph in my earlier comment is the important thing. For an event lasting 6 minutes, there is no way to do it as quickly by relying on fat.

Unless you're aware of some data suggesting that fat-adapted athletes can burn fat at higher rates than the Volek study suggests...

[bloomp]

As I was looking for a link to the Volek study to post in response to this, I came across an article that explains the point I was trying to make better than I could have. I'm just going to post the link here: http://www.runnersworld.com/sweat-scien ... at-as-fuel

The issue is that even fat-adapted athletes can't burn as many total calories per minute. So even though they were able to burn more fat per minute than the non-fat-adapted athletes, they were still producing less overall energy. Again, the curve of the graph in my earlier comment is the important thing. For an event lasting 6 minutes, there is no way to do it as quickly by relying on fat.

Unless you're aware of some data suggesting that fat-adapted athletes can burn fat at higher rates than the Volek study suggests...

Fat adapted athletes still have glycogen to use. And 4-5 six minute races over the course of several days is not enough to deplete those stores. Yes, top speed requires carbohydrate to match metabolic demands. But eliminating dietary carbohydrate doesn't reduce your glycogen stores to the point that you can't maintain high intensities in training or racing. You are not using any single substrate at any given time - and while someone relying on carbs shuts down fat metabolism when they take in carbs, someone that is fat adapted always has complete access to stores of fat and carbohydrate.

Again, on mobile, but I have data that shows glycogen stores at various levels of carbohydrate intake. The liver is quite good at gluconeogenesis and that glucose readily can be converted to muscle glycogen.

[SDsweep]

from the link I just posted: Of course, there's a flip side to fat adaptation. The high-carb group was able to burn carbs at a higher rate: 7.83 g/min versus 5.65 g/min. Which is better? That might depend in part on whether you're able to ingest carbs while running without any problems.


The fact that fat-adapted athletes can burn carbs is accounted for in the graph I originally posted. They do burn fewer carbs though. The question is which leads to the highest total calories per minute, and you haven't said anything about that other than, "Trust me. I've studied this, and I have data."

[bloomp]

from the link I just posted: Of course, there's a flip side to fat adaptation. The high-carb group was able to burn carbs at a higher rate: 7.83 g/min versus 5.65 g/min. Which is better? That might depend in part on whether you're able to ingest carbs while running without any problems.


The fact that fat-adapted athletes can burn carbs is accounted for in the graph I originally posted. They do burn fewer carbs though. The question is which leads to the highest total calories per minute, and you haven't said anything about that other than, "Trust me. I've studied this, and I have data."

The graph you refer to does not appropriately reflect the levels of fat oxidation that Volek reports. It also does not include carbohydrate metabolism.

The graph reports a fat adapted athlete to be able to burn 800kCal/hour - however the 1.54g/min of fat oxidation that Volek reports comes out to 831kCal/hour. Not counting the 5.65g/min of carbohydrate that a fat adapted athlete is still able to burn. So that is an additional 1356kCal/hour available to a fat adapted athlete. Certainly these substrates are metabolized at those rates at varying intensities - but if you need to exercise for six minutes and complete a 2000m race, you still have the ability to metabolize enough carbohydrate for work at or above your VO2 max. Even IF you wanted to run a 2 hour marathon, that's 13.1 miles/hour, and about 1300kCal/hour in demands. That's a rough estimate, but we know that running a mile is ~100kCal depending on body weight. Since we know that marathon pace is at or below the LT, we know that fat still contributes significantly to metabolism at that intensity.

Contrast that with a 2:05 marathon runner who is constantly supplementing with carbohydrate in order to avoid bonking - sure he has the ability to oxidize just shy of 1900kCal/hour, but once you start taking in any glucose, the insulin response blocks a majority of your fat mobilization and oxidation! Thus, he has to rely on exogenous glucose for much of the race. Your body simply doesn't have 3800kCal of glycogen stored, and even if it did, you will bonk with about 10-15% of that still available. An elite marathoner has such little muscle mass that he might have 2500kCal of muscle glycogen at the start of the race.

You can fuel the engine either way for the same result, at least looking at the biochemistry of the matter. Whether anyone will test such assumptions is out of my control, but the bioenergetics match up.

[bloomp]

An update:

http://www.metabolismjournal.com/articl ... 0334-0/pdf

"We studied two groups of highly-trained competitive ultra-endurance athletes who were well matched in regards to training status and physical characteristics. The main difference was that the LC athletes consumed 6-times less dietary carbohydrate than LC athletes (82 vs 684g/day) for an average of 20 mo. The most notable findings were that compared to HC athletes, the LC keto-adapted runners showed: 1) two-fold higher rates of peak fat oxidation during graded exercise, 2) greater capacity to oxidize fat at higher exercise intensities, 3) two-fold higher rates of fat oxidation during sustained submaximal running, and 4) no differences in preexercise muscle glycogen concentrations, the rate of glycogen utilization during exercise, and the rate of glycogen synthesis during recovery."

[Remomex]

But was their performance helped (LC) or hindered (HC) by eating a lot of carbs/not eating a lot of carbs? Or does the body make other adaptations that "equalize" the adaptations found in this study for the LC athletes?

[bd_sculler]

Paul, Thanks for that update. That is very interesting reading.

But was their performance helped (LC) or hindered (HC) by eating a lot of carbs/not eating a lot of carbs? Or does the body make other adaptations that "equalize" the adaptations found in this study for the LC athletes?

From page 19 of the article:

While we showed distinct differences in metabolic responses between LC and HC athletes, we did not measure performance. It will be important for future work to address a range of performance outcomes from endurance to anaerobic capacity to strength/power, as well as sport and/or military-specific tasks

Those with academic backgrounds will notice the military reference (always thinking about the possibility of grant money from the military.)

[bloomp]

But was their performance helped (LC) or hindered (HC) by eating a lot of carbs/not eating a lot of carbs? Or does the body make other adaptations that "equalize" the adaptations found in this study for the LC athletes?

Again, I don't make a habit of preaching one diet that will work for every athlete.

The point of the study is that LC does not inhibit performance, and in fact you can perform to the same level as someone on a HC diet. The fact that you are essentially sparing glucose/glycogen at lower intensities makes LC much more favorable for ultra athletes. But being able to have high levels of fat burning at 70%+ of VO2 max is incredible.

For something (as bd says) like military operations, being able to operate at a high intensity, or high level of consciousness for prolonged periods of time without eating is incredibly beneficial. Fats also tend to keep better than carbohydrates and have a much higher caloric density. See: pemmican, done right before preservatives were available. IIRC the folks that race across Antarctica generally just eat butter.