giantlover4

Anyone ever try the keto diet for endurance? Or just simply replacing carbs with fats?

hyegeek

That how I eat. My longest ride eating that way is 144 miles. I only needed to snack on a few nuts (mostly to keep from feeling empty) to keep going.

Last summer, I crossed Washington state on the John Wayne Trail. My travel buddy ate a "normal" diet, I was eating a keto diet. My buddy would snack throughout the day. It took me more than two days to actually start getting hungry. I ate before that since it seemed the thing to do. After that, I did eat pretty big meals (still keto) to keep going.

curlyque

even the leanest person carries 30,000 calories of adipose tissue.....if you are keto adapted, you're not likely to run out of fuel during a sustained endurance activity. I also eat nuts and other calorie dense fats during tours or on long day rides.

gregf83 

If you're not keto adapted, you're also not likely to run out of fuel during sustained endurance activity. If you want to go a little faster however...

curlyque

If you keep eating the whole time, I guess you're right. Whatever works

Sorry, glucose is only influential during anaerobic activities, not a 'little faster'

eriku16

Umm... no...

steve-in-kville 

I ate paleo for about 8 months. I had to stop. I kept slipping into starvation mode. Like where I was only eating 600 cal./day. Started to gain weight, not loose. I had to do something so I switched it up. Know I feel better.

gregf83 

When riding close to your 1hr threshold power, virtually all the energy is coming from carbohydrates. If you're doing long endurance rides fat contributes a significant portion.

curlyque

If your doing long endurance rides, you require 'no' carbohydrates.... ketones supply all the requirements

curlyque

Let me correct that to 'anaerobic threshold'

Carbonfiberboy 

Still totally, massively, incorrect. Doing the sort of riding you are limited to by your diet, you can greatly reduce the contribution of carbohydrates to the lower ranges of your potential power. That works very well. In fact, all long distance riders including those who fuel with carbohydrates, practice this helpful discipline of doing endurance rides. However, there's a big space between VT1, the upper limit of the pure fat burning range, and VT2, the anaerobic threshold. Carbohydrates are necessary to spend much time in that zone, even if one never rides at anaerobic threshold. During yesterday's century, I spent about 1/4 of my riding time in this carbo-powered aerobic zone. To accomplish this, plus about 20 minutes above anaerobic threshold, without bonking, I consumed ~1000 calories of carbohydrate, and was still able to hold 18-20 mph during the last hour. I'll be 70 in June.

Someone who isn't going riding in an hour can dig up the graphs showing this.

gregf83 

I don't need to eat any carbs during long rides either. That doesn't mean my body isn't burning any. My understanding is that being on a ketogenic diet significantly increases fat oxidation during low to moderate intensity and significantly lowers glycogen use. I don't think it reduces carbohydrate oxidation to zero, however. The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists was an interesting read.

It seems like it works OK, although not for me personally. Im not interested in increased kidney stone risk and wouldn't like the decrease in high-intensity performance.

curlyque

You're entitled to believe that what works for you is the best choice, as am I.

However, the notion that the body cannot sustain a high level of output over many hours fueled by ketones, alone is completely archaic.

gregf83 

Sustaining a high level of output over many hours is an oxymoron. The study I linked clearly found the ketogenic diet resulted in reduced maximum power output.

If you've got some useful studies to read please share.

curlyque

I got a better idea..how about a bicycle mount for a glucose IV drip...then you can get a steady sugar fix and keep up with all your friends

Over and out

gregf83 

Evidently, a ketogenic diet also restricts the ability for intelligent conversation. Enjoy your ride.

DaveLeeNC

Independent of ketogenic or not stuff, I don't think that this is correct.

From all that I know (I am hardly a metabolic expert) this is just not true. I don't think that your fat metabolism drops when your effort level ramps up from VT1 to VT2. From all that I know it simply 'maxes out' and the power gap is filled in with other (not fat) sources and 'virtually all the energy is coming from carbohydrates' when doing a 1 hour threshold ride is just not how it works.

Am I wrong here?

dave

eriku16

Fat metabolism in exercise. - PubMed - NCBI

gregf83 

Yes, I believe so. Fat oxidation peaks at around 65% of VO2Max and drops to zero around 85% (roughly threshold type efforts).

DaveLeeNC

Interesting. From Chris Carmichael's Time Crunched Cyclist (page 23)

As your intensity level rises above 60% Vo2Max, the contribution from the glycolytic system starts to increase, and then it really ramps up quickly once you reach lactate threshold. Because glycolysis only burns carbohydrate, the overall percentage of energy coming from carbohydrate increases dramatically as you intensity increases from lactate threshold to VO2Max. You're still burning a lot of fat, however, because your mitochondria are also still hugging along as fast as they can.

Based on what has been posted here, that is simply wrong. Interesting. Thanks.

dave

Dunbar

You can actually have your respiratory quotient measured to see how much of each you're burning at a given intensity.

Carbonfiberboy 

It looks to me like the question of fat oxidation at increased exercise intensity is very, very complicated:
https://www.aleixo.com/biblioteca/obe...metabolism.pdf

My understanding of the above link is that the muscles are perfectly willing to continue to use fat at high exercise intensities, i.e. 85% VO2max, but that the body decreases fat transport from adipose tissue at high intensities. They say that this whole issue has not been well studied.

no sweat

Of possible interest Fat-Burning Runners: Study shows benefits of keto-adaptation in athletes' performance -- Health & Wellness -- Sott.net

I wonder how long it takes to get fully keto adapted... and what happens to the fully keto adapted athlete that eats "too many" carbs for a day or two.

My own experience with keto was a couple of weeks at most. It's a great way to shed a few pounds in a hurry. I've never tried to maintain weight on a keto diet. Maybe in part because of this, my athletic performance while keto was absolutely dismal.

Carbonfiberboy 

-- Peter Defty, President of VESPA, the article author.

I'm running right out to buy me some wasp extract. As some article commenters said, it might be a good idea to wait for the study's publication in peer-reviewed journals. The problem not addressed is if fatty acid transport from adipose tissue at high intensities can be improved by diet, and if this is the case, what is the mechanism? It seems unlikely to me, even if Mr. Defty's wasp extract becomes very profitable.

no sweat

I was merely interested in the fact that people are claiming decent VO2s for athletes on a low carb diet. If that's true, I'd like to know how they got there and what the gotchas are, that's all.

I have no clue who Mr Defty is and don't vouch for him. "wasp extract" is mentioned nowhere in the article.

The mode of your response is somewhat provocative and annoying. I just thought I'd point that out.