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Joe Friel

Hailey--I wish I could tell you but that is an unknown. My experience has been that I need very little carb during exercise. I just finished a 481 mile week riding (actually, 6 days on the bike--took a day off) in the mountains of Colorado with over 35,000 feet of vertical gain. During that week I drank a total of 5 bottles of sports drink. That's less than 1/day with an average of 80m/day. Have gotten one email and one comment from athletes who have done IM on water only since they eat LCHF. So I think we have a lot to learn on this topic.

Joe Friel

Mark R--An interesting topic but I know of nothing published on this topic. Good luck!

Joe Friel

Bill--I don't substitute anything for them as there is nothing being "lost" by not eating them.

Zach Bannow

I was surprised to read that you eat bacon, and deli turkey as they are not paleo... Anyway, along those lines, can you describe other ways you have deviated from the Paleo diet as outlined in the book you co-authored? I'm curious how this has affected your micro nutrient intake. With very little fruit, do you now have to take a multi-vitamin? I thought more than 3 eggs per week was bad for cholesterol... I've been paleo for about 4 years so I'm all ears for tweaks to the paleo concept.
Best Regards,



Interesting article.

I have personally found that I gain weight when I eat too much meat.

When I switch to a pescatarian diet (fish only) but with slightly elevated carb intake I lose weight quite well and generally feel better too.

Have you heard of this before?

FYI high fat is difficult for me due to intolerances to dairy.

Joe Friel

Zach--Things change as the research grows. Paleo now includes bacon, multiple eggs, etc as per Dr. Cordain, my co-author, who is pretty much the leader on this topic.


Joe, Thanks for this post. I've been reading all I can about LCHF since January. I've especially found Peter Attia, Tim Noakes and Gary Taubes to be helpful. I've been training for IM Wisconsin (my first IM)and have fueled most of my long sessions with <100 calories an hour of Generation UCAN, a very slow release carb that does not provoke insulin an insulin release. However, I've added 1 bar per hour to my long bike rides recently because I've been worried about going against so much conventional wisdom in my first Ironman. I"m a close follower of all your writings so it's a great relief to see you open to LCHF. Any thoughts on UCAN only or supplemental bonk breakers during the bike for my first Ironman? I feel that I am pretty fat adapted.

Joe Friel

KenSMoore--Gosh, I wish I could tell you what to do. I'm still learning about the topic you bring up here. So far just anecdotal stuff. Had a type 1 diabetic whose is also an MD write last week. He did his first IM on water only. He didn't say what his time was. He was satisfied with how he did. I did 481 miles in the mountains of Colorado in 6 days last week with 33,000 feet of climbing. Some very long days and some intense climbing. I drank about 5-6 bottles of sports drink for the entire week, I'd guess. Otherwise, just water. No solid food (other than a HF bfast every day). Was never bonky or unduly fatigued, Rode as well as I normally have done in past 5 years when I used much more carbs. Could I have gone without it altogether? Don't know. But I'm certainly moving that direction.

Michael Levy

Joe, in regard to the above discussion:

"Joe, if it's true that your "body has adapted to using more fat for fuel thus sparing glycogen," doesn't it seem likely that during a long, sub-threshold race you could take a bunch of carbs and improve performance relative to pre-adaptation? Is there no science on that?

Posted by: Michael Levy | 08/08/2013 at 06:30 PM

Joe Friel
Michael Levy--That would imply that fat was not adequate in providing fuel for a subthreshold effort. That's not the case at all.

Posted by: Joe Friel | 08/08/2013 at 07:36 PM"

Right, glycogen stores are a likely limiter in longer efforts. It sounded like you were postulating that your low-carb adaptation means you're burning a lower carb:fat ratio at sub-threshold efforts. That would explain your being able to go longer without carb intake now. What I'm wondering is, if that is the case, do you think you could go even longer, or at higher intensity, with during-exercise carbs? In other words, the weight management benefits are great, and it's neat that you can ride five hours without taking carbs, but do you think you'd perform better in a sub threshold race now vs pre adaptation given the same in race nutrition?


Joe, I am interested in reading more into nutrition, do you have any suggestions for good books/papers to read on the subject? I am from a science background, so I would rather have more detail than less.

I usually only use energy drinks for high intensity interval session ~1hr. Is there any evidence/logic that suggests that not consuming carbs for this sort of training would reduce the training's effectiveness?

Justin Kee

Joe - I've decided to go cold turkey and switch to HFLC. Any research on how long it takes the body to switch over? sorry i havent done much reading on the subject yet. I only race cyclocross and mtb, shorter events. At the intensity level of those two disciplines is it realistic you can sustain the efforts for 1 hour cross events and 2-3 hour mtb with no carbs? love the blog


Interesting. I ran LCHF diet for over 2 years and found my energy levels to be, well, very level. Quitting sugar and other HGICs was one of the most difficult dietary changes I ever made but once my body adapted I found that I could run on fats alone. However, I was not training like I am now, and in fact have switched to a more "traditional" endurance diet because that's what I've read I need to do. Now I have some new food for thought. Will be interested to see/hear/read how other athletes do on this diet on race day. Thanks.

Joe Friel

Justin--I wish I knew the answer. Still learning.

Joe Friel

Michael G--The research that I've found says there is no downside (performance-wise) from using carbs right before or during exercise.

Joe Friel

Michael L--I wish I knew the answered to all if your questions. I don't. There is inadequate research on this so all I can go by are anecdotal evidence, including my own.



A couple of experiences/observations on LCHF diet or Paleo Diet.

Personally, I don't really apply to the discussion. I'm 38 years old, and while I have seen some changes both in performance and recovery, I have not witnessed any significant body changes in regards to muscle or fat.

I have tried LCHF and I had mixed results. I'm a small rider, but muscular for my build--too muscular when I started road racing. I wanted to become a stronger rider in the mountains, so I started the Paleo Diet to shed some muscle and extra weight. It worked, and I've been riding a 2lbs per inch ever since.

There was a price to pay, though--recovery! I did not recover as well on the LCHF diet. For me, it was a short term strategy to get leaner. Once I went back to a traditional diet (carbs) I started to ride stronger, recover better, and feel more enthusiastic about the bike. Plus, I stayed light with a moderate diet.

I also have a friend--riding buddy--who is approaching his mid 50s and is totally committed to LCHF. He looks amazing, and is very explosive for his age--strong climber. But, when we head out for a few hours, he's always tired and fighting fatigue. He doesn't train excessively, but he's dogmatic when it come to the glycemic index. Again, he's benefited from LCHF because he's lean and mean, but what good does that do you if you can't recover from one ride to the next?

My experience is that LCHF is a good temporary strategy, that should be slowly replaced with a moderate diet.

Life is short, eat some pizza now and then.



Hi Joe, is it similar to the Atkins diet? I tried the Atkins diet some 20 years ago, lost good amount of waight but stopped it due to the repports on not knowing the side effects if followed for long time. Now I´m 48, my weight is 95 Kilos (209 pounds?)and I was going to start the paleo diet.

I might follow your idea and become my own rat lab and try a paleo/HFLC diet.

Excuse my poor english!!
Regards from Lanzarote, Canary Islands

Joe Friel

Pautaplana--Yes it is similar to Atkins. Good luck!

Kasper Sørensen

Joe, have you any experience with clarified butter? It seems like an appropriate and fairly affordable source of fat.

Joe Friel

Kasper S--No, I haven't. Let me know what you find out.


Hi Joe, great post .I've been thinking for some while now that dumping loads of sugar into my system probably isn't a great idea so this all make sense.
One question. you say that you still use hi GI food/ recovery drinks after long/intense rides. In the book "The Art and Science of Low Carb Performance" the advice on p60 "Post-Exercise Carbs" states that ".....Consuming even small amounts of carbs after exercise rapidly decreases the release of fatty acids from fat stores and oxidisation of fat in the muscle..."
The authors go on to say "....Over-stimulation of insulin by fast acting carbohydrates also can have a more insidious effect-diverting glucose into fat storage.
Any reason why you are deviating from this?

Joe Friel

DeanTonna--Yes, I've read that too. I'm still in the early stages (11 months) of eating LCHF so am still learning. I'm just a bit reluctant to not use carb in recovery at this stage. I continue to experiment to see what works best for me. As I said in the body of this post, Nutrition for sport (or probably life in general) has a lot of individual variables. I'm trying to figure out those that work best for me. I may some day not use carbs at all post-workout. But I'm not convinced that's best for me--yet.

Christofer Bamford

Hi Joe,

I'm a cyclist and tried LCHF for about 6-8 months I guess. Here iswhat I found:

1.Weight loss...absloutely. It did level off thoug at a BMI of about 23-24(which isn't too bad).
2.Endurance, no change and as for you, I could excersise on water.
3.The "lactate"/burning leg feeling when climbing - Vanished! I mean COMPLETELY gone.
4.Recovery - improved, particularly onthe aches and pain side.
5.I lost my top end and got dropped during high intensity sections that lasted longer than a couple of minutes.There was no pain or discomfort as when you blow, just a lack of power. It was like pressing the accelerator to the bottom in a car with a small engine. For a bike race, (as you know), this means that you are on your own sooner or later.

I'm thinking that for next year I might return to LCHF during the base period. Teaching the body to burn fat in such an extremely efficient manner,surely must be a good thing. Then during the build period, I'd start introducing carbs again.

What do you think about this approach?


Joe Friel

Christofer Bamford--I think it's certainly worth a try. And I'd like to hear what you find out. There's a lot to be learned about LCHF for anaerobic endurance like we find in bike racing.


Thanks for the great post Joe. Welcome to the LCHF world. I've been LCHF for almost 2 years now. I can confirm that my endurance is through the roof and recovery is lightening fast.

As far as high intensity workouts/races goes, I've been using the targeted carbs strategy. Basically, for a race or hard speed workout, I'll use a gel after a really thorough warm-up. And I'll continue to use one gel every 45/60 mins after that depending on intensity. Works great, try it. The gels are like rocket fuel when you live the LCHF lifestyle. During exercise, your insulin response is very small to ingested carbs so the gels won't kick you out of fat burning mode and you'll have some extra blood glucose for those hard efforts/sprints.

For recovery, after races/speed workouts/long runs, I go super low carb to avoid the pro-inflammatory effect of carbohydrates.
We also have a great support group on FB for LCHF runners called runKeto. Come check it out...

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