My first fat adapted cycling failure


Why did you get those numbers. Thanks for the info, btw.


(Tom Seest) #22

Fasting, without exercise drives your glucose numbers low, and your BK levels high. But, it takes time for your body to adapt to these levels. When I first started riding, I’d feel awful if my Blood Glucose levels went down in the 90’s. Then, I adapted to the numbers in the 60’s, and so on. Some people have hit the 30’s. So, fasting is an excellent way to get there. But, if you’re miserable when you get there, your body isn’t utilizing them correctly. With fasting and riding, or Keto and riding, you always go based on HOW YOU FEEL. If you feel bad, eat and live to ride another day. It takes time to build up. It’s really no different than learning to ride a century. It takes time and effort but you eventually get there.

(ianrobo) #23

Tom the key is how you feel, I like many others on fasted long rides took emergency rations but the first day I knew I was fines when I did not bother …


You make good sense. In all the months where I’ve done intermittent fasting and then worked out I felt fine. I just need to train up for longer bike rides without gels or gatoraide type stuff.

(ianrobo) #25

correct and the only way to do it is to extend the ride length without carbs. I did this by doing circular routes around home so if I felt like bonking I had only a short ride home, I never did.

For me it is mind over matter … if you have been strict Keto and exercising like that you will be fat adapted in 3-4 months.


Thanks for this post. I’m about to leave for my racing club ride after 1 week on keto diet (actually 3 days of fast and 4 days of keto). I won’t be surprised if the ride is a bit of a disaster for me. I have no carbs worth eating in the house so only eggs for breakfast. Maybe someone can tell me if, at this point, I can eat carbs before a fast 50 mile ride to get me through the ride (largely to visit with my buddies).

My brief history of this diet was to eat a keto diet back in June. My weight tanked and I loved it. But I not only bonked on a century I did, I got so nauseous that I threw up. I only gave up the keto diet because of lengthy stay in Italy where carbs are king and no way I was doing to pass on that fantastic food and vino! So here I am back in the states and on a keto diet to lose those italian pounds I gained.


It seems like it is totally dependent on the individual. Some become totally fat adapted more quickly than others - so it seems. When I started to bonk I had some gel chews - they made me feel worse. Good luck with the ride. If you are not adapted to burning fat during rides I would ask someone to share some carbs along the way to make the 50. I am going to experiment with Ucan carb mix and electrolytes to see if that works on distance rides as I try to get fat adapted.

(ianrobo) #28

just for reference did this today


(ianrobo) #29

too many people do not give it enough time thats the whole problem. Fat adaption is not just after ‘keto flu’ goes it is probably a good 8-12 weeks after. But people think they are then dive into long exercise and then unsurprising bonk.

Personally you have to start riding training rides fasted, first an hour then 2 hours, work up to 4 and fine, do this and then understand your HR/power zones and where to place yourself you will be fine.

For reference today I was average HR zone 3, many say this burns carbs but as FASTER shows, the fly fat adapted athlete is at this level very able to burn vast majority in fat.

(Mike Glasbrener) #30

Data for techie people

(ianrobo) #31

as usual Peter with proper science. However he talks about a state of Ketosis and this may not be fat adapted. We all accept top end power is affected but for 99% of us thats not a problem, it means I can do 160km without stopping (except for water and getting lost today !!) and roberts have to stop and despite being older and not as fit as some I am faster !

(Mike Glasbrener) #32

:grinning:. I’m trying to find my groove again post fire. My fat adapted riding has been great. My ‘effin knees are discouraging though.

(ianrobo) #33

knees are awkward only thing to do is to rest or have to take it easy but inflammation should be low ? how about trying zero carb for a while ?§

(Mike Glasbrener) #34

Thanks. It’s cartilage, meniscus and a bit of ostioperosus. I had arthroscopic on right knee and was planning on getting left one done then fires threw a monkey wrench into those plans. I’m going to try and get a follow up appt. with my doc. Because so much housing and medical facilities were damaged/destroyed medical here will be goofy for a few years. I definitely want my experienced doc to do my left knee, not a “rookie”.

I do 2-36 hr fasts a week and am fairly strict keto the other 5 days. I think I may look at 16/8 the other 5… My inflammation is pretty good I think except for a bit of a deviation the last month.

(ianrobo) #35

now on fasts, I listened to latest Primal endurance podcast with Brad Kearns today and that had an interesting discussion on them if you are exercising (ie. long fasts not needed and may do more damage) but Brad is doing a lot more exercise than the average person !


In the end I ate a banana at the bike shop at the start of the ride and then rode slowly with a friend recovering from an injury so no hammerfest for me today. I felt fine. I’ll just experiment hoping not to feel so nauseous as to vomit ever again! I do like to think I’m somewhat able to burn fat because the last 2-3 years I’ve not eaten any breakfast and gone on 50 mile hard rides - but otherwise not on a keto diet. Kept me thin while previous breakfast eating was doing nothing to maintain my weight - as in I was gaining over time.


I found this awhile ago. Fantastic read.

(Stu Shez) #38

Hi @Mkellett

I found your story very interesting…

First of all, I should say hi. It’s my first post here having just signed up. I was signposted to the site by someone on a generic keto FB page. My posts or questions about training / cycling on keto were falling on deaf ears over there where the biggest concern is weight loss (no bad thing I hasten to add…). My last post below:

I had a bit of a mad experience yesterday (now Sunday)… I’m six days into keto and no where near adapted yet. I’m a mountain biker and yesterday I ran our club’s intro ride for new members at Llandegla in north Wales. This is a relatively easy ride, circa 13miles and 2.1k ft of ascent.

By 8 miles I was suffering, by 10 I thought I was going to have to lie in the snow and die! By the time I finished I could barely string a sentence together and was dizzy as feck. Driving home was a nightmare, vision was going, micro sleeps and allsorts. This was so bad I had to pull off the motorway for a rest, I couldn’t keep my eyes open.

I’ve ridden whilst doing keto in the past but never have i struggled so much. My fitness is good - last Sunday I did 32 miles off road in mud and was fine! I’ve never felt exhaustion like I did yesterday.

I came home and went to bed for two hours, I still felt totally spaced out all night.

Lesson learned for me. You need to be far more fat adapted than 6 days in before you start to push your endurance at all. I can’t wait for that to happen!

Having read all of the posts above I can see I’m being wildly optimistic in terms of my timescale for fat adaptation - I had thought a fortnight to a month but clearly that’s not the case. In the past when I’ve used keto I’ve noticed that after four or five weeks I have endless energy for steady cycling, when I need more “High octane” power though is when I struggle; hills, sprints, that sort of stuff.

Yet another facebook group have advised UCAN / B-Ox Juice as pre and mid ride solutions to provide keto friendly carbs (if there is such a thing?) but I don’t yet know enough about keto /those substances to make an informed choice.

Targeted keto seems like a bit of a cop out and again, maybe I don’t know enough but I’m concerned that I would struggle to get back into keto quickly, thereby losing the benefits of fat burning.

Hopefully if I hang around this forum for a while (it’s great by the way, very informative!) I’ll pick up the info I need and soon be able to make better choices and not bonk as badly as I did last Sunday - I really cant emphasize enough, this was beyond anything I’ve ever experienced in a lifetime of different sports and exercise. I really was going to crash the car if I didn’t get off the road it was that bad…

ATB, Stu.


Hey Stu -

Yes, the message we are getting is that one may, or some of us may have to slowly adapt to be a fat adapted athlete after being fat adapted in ketosis. I am no expert but I have been reading every possible thing I can. I am now seeing that the keto flu - which would kick in around where you are has to do with a lack of salt and electrolytes. Perhaps that is it?? I am now thinking that, while I bonked badly while on some electrolytes, I bet I should have had more of them and focused on getting salt. One thing for sure, the info on the “Keto Flu” should be followed with quick instructions on how to get around it - SALT.

A separate experience I had was following recommendations for fat adapted athletes and before a 100 mile ride consumed a can of coconut milk, protein powder, amino acid, and Ucan. It was just too much for me to have had and I had a bad stomach for the first 50. Once that cleaned out at a rest stop I just consumed a few mini cups of pickle juice for 50 miles - and I felt strong as hell. At the end up a hill I found my self sprinting past cyclist that had passed me miles before. I am going to test myself next season (it’s cold here in Washington DC and I don’t do really long rides in the winter) - I will try just a higher level of salt and electrolytes and then try doing that with Ucan for a really long ride and see what happens.

(Todd Allen) #40

One difference for me is that after bonking I don’t need to eat to recover. Merely resting for a while is sufficient to recover enough to continue on at a moderate pace.