LCHF/Keto diet - effect on training/performance

Hi there,

I’m think of starting this type of diet to stop my chocolate and rubbish food addiction. Is there anyone else on here who uses a LCHF diet and if so, how has it effected your training/life in general. Any comments/discussions welcome.


I’ve been Living a LCHF Lifestyle for the past year. I can safely say that my 2018 season has been the best ever!

While it took a while to become fully Fat Adapted; took me 3 months or so… started in October of 2017, I have not needed Sugar or Carbs at all on any rides I’ve done to date.

I suggest you start now in the off season and take some Cliff BLOKS in your back pocket as insurance. I did that and never needed them, but it was nice to know if something went wrong, I’d have an easy sugar intake.

Electrolytes are key. I highly recommend Ultima Electrolyte Power. Buy in bulk.

As my body fat has dropped, along with TrainerRoad Workouts, my Power to weight ratio has increased and I stress, 2018 has been my best season.

I plan to stay LCHF for the rest of my life!


I’ve done LCHF and it did indeed “cure” my sweet carb addiction. However, science says it’s not all that useful for either training and/or performance.

Easy way to think about it: low intensity = low carbs; high intensity = high carbs.


As you can see, alot of Nay sayers when it comes to LCHF… I will repeat what I’ve said to others… try it, if it works for you, then it works, if not, go back to Carbs!


I’m not a naysayer of low carb, nor a cheerleader for high carb (I’ve done both with success), but one shoe does not fit all sizes.

Utilize the proper diet to support your lifestyle/activity level – whatever that may be – and all will be well.


I tried a Keto diet for nearly a year. I will share my experience. I have participated in endurance and ultra-endurance events for 16 years, I’m in my mid 40s.

It took me two - three weeks to get into Ketosis, seem to remember it being 18 days (note: for 16 years I have never really eaten more than 250g of Carbs a day (except holidays), so that might I could get into Ketosis reasonably quickly.)


  • Lost 42 lbs
  • Body FAT <7% (this also turned out to be a con)
  • FTP stayed the same during base and build cycles – 5 – 6 months
  • Once in Ketosis felt the most alert I ever have in my life
  • Could comfortably ride up to an Intensity factor of about 0.8 for 3 – 5 hours
  • Could ride for this duration without eating anything – I’d have bullet coffee before I left the house, I did put some 60%+ Fat cream in a zip bag for ride 4 – 5 hours a few times.
  • W/KG increased for the base and build period


  • Felt crap on the bike for the first two weeks until in Ketosis
  • Could not complete Specially, sessions became too intense
  • Struggled to not drop further weight
  • In the 6 – 12 months got ill several times and couldn’t train consistently as a result FTP dropped to an all-time low
  • The most shocking thing was when going back to a moderate Carb diet I put on all the weight I had lost plus 10 lbs

I decided it wasn’t for me. I don’t think I have a particular bias. It might be worth a go, it might be for you. Higher the performance, for me anyway, it’s not going to work out. Final note, I have since got back to about 8% body fat on a <220g of Carbs per day diet and had my best year ever on the bike this year. My power curve is the highest it has ever been across the board as well.


This! This is exactly what I’ve being saying to people… Try it… if it works for you like it does for me, then bingo… otherwise go back to carbs!

@Bbt67 Thank you for your post and personal snowflake experience!

1 Like

Not sure why my post has been hidden / now awaiting moderation, do i get awarded a badge for that?

^ Good point about Electrolyte’s if you don’t keep on top of them then there is a good chance of keto headaches.

And yes I am special!

1 Like

Interesting, thank for input all. I’m keen to try it. I just want off the cravings and the copious amount of trash I eat (and cant stop eating). I am worried about drop off in high intensity hit outs and associated times ( 10 and 25mile TT’s) but as said above, the longer you go the lower the intensity and the less reliant on carbs you should be.

I’m on the electrolytes. been reading about it. Is the electrolytes just for the transition time to be become fat adapted or permanently?

Heavy electrolytes during the transition phase, and then logically there after. I.e. I use them when I go on longer than 1 hour rides. Other than that, there is enough pink salt in my day to day eating, that I no longer need to glug it down like I did when I began.

Hey Brad!

We have talked about this on the podcast a couple times. You can hear an older discussion on this here:

All in all, we recommend against a Ketosis diet when training because it usually doesn’t give you enough fuel to perform as well as you usually do or recover from your workouts sufficiently. Recently, we talked about why the keto-diet isn’t practical for cyclists which you can check out here:



I’ve been lchf for a few years now. It’s been great for my overall health, but this isn’t a health forum so I won’t bore you with that. What you need to know is the first month or 2 you are going to feel seriously weak in your workouts. Just go with it (reduce intensity or shorten your usual workout), and one day you’ll go to workout and it will be like a veil was lifted and all your previous performance is back, and you can resume building.


Some food for thought when looking at endurance performance - pulled from The Endurance Diet by Matt Fitzgerald.

TL;DR version.

  • Kenyan runners make up 17 of the 20 fastest male marathon times in history, 15 of the 20 fastest female marathon times in history (could have changed since published).
  • Their diet consists of close to 80% of daily calories from carbs.
    Note, correlation doesn’t equal causation

But the scientific literature points to higher carb intake for increased endurance performance. Definitely have a listen to the links @Ian posted.



I have some experience that might help. Similar to Bbt67, but never was ill just less time overall on it. I really enjoyed being on Keto while cycling. As a disclaimer, i did it for 3 months hard-core. I managed macros, electrolytes, vegetable intake and little to no stevia/monk fruit… really easy to maintain and no desire for sweets. I went from 84kg to 78kg in this period and FTP increased 3%. (4.1 w/kg at the time)

As the podcast points out, there is an issue with longer high intensity workouts, however increases avg power over longer endurance rides. Here are a few scenarios i found on the bike.

Regular weekend 3 hour climbing rides:
I’d have enough energy for 1-2 early ride sprints with full effort. I didn’t feel there was any loss in performance and finished as expected for most. After glycogen depleted (it is noticeable) there was nothing in the tank for high efforts… HOWEVER, I found a sweet spot in performance around 135bpm (I’m 30) that i could ride all day at even after the earlier exhaustion. Yes, in this case HR is much more the limiting factor than power (you can read up on the science of optimal fat burning zones) I couldn’t push past the threshold, but had no reason to go less. Contrary to what Coach Chad said in the podcast, i found some sugars can be added during workouts to improve performance, like jet fuel, just it doesn’t take much nor can your body handle much and it won’t magically bring back your regular performance for the ride.

1x/mo 160km ride:
I had my fastest time for this route and also had some “Show-off” pulls for some randos we passed on the route. I had no body aces such as back, hands, neck. My mate who usually rides faster was struggling at the pace and i pulled most of the last 60km back while smiling and joking… we were all weirded out (maybe the mates more pissed because i felt so good) For fuel, I had 2x string cheese, a pack of fatty ham and other then sugar free sodium, potassium, magnesium, calcium + aojiru mix, i did have 1x500ml diluted Sports drink (Aquarius) with plenty of sugar over the course of the ride. Legs were tired after of course, but hunger pangs were just not so bad that i could manage the food intake after.

Sprints and CX races:
Did one CX race. Its only 30 minutes, but there was no sluggishness, lack of power or any sense of a difference in performance in concentration. I did want to do more races to see if this was special case, but I promised myself only 3mo and the timeline became more important than staying on it.

What i found:

  • It isn’t as easy as just upping your fat content, watch protein levels and eat your damn salted veggies.
  • Endurance rides were more efficient from budget and calorie intake
  • <30 minutes of intense exercise showed no noticeable drop in performance
  • There is a sweet spot “fat burning zone” which you build your
  • General dieting afterwards was much easier
  • Neutral mood throughout day regardless of meal times… you may hate your less productive colleagues more.
  • Best HDL/LDL readings of my entire life.
  • Everyone thinks your crazy, so make sure to be prepared with the science to justify your plate of mayo.
  • You’ll learn a lot about your body, whether you have sensitivities towards food groups or just how to properly fuel.
  • When you cycle off, you will gain some weight from water retention. Don’t worry, it is easier to go back on the next time
  • There is no more celebratory beer after rides/ races… bring your gin and give shit to your uncivilized mates as you weep inside.
  • You have nobody to talk with about it and there is little studies to support endurance use to help you manage it.
  • You desperately need: sodium, potassium, magnesium, calcium… more than you can expect so add salt to everything… everything
  • You find even after being on keto, longer ride fueling isn’t such of an issue and your body seems to better manage switching the energy source. It isn’t instant, but it is noticeable.

I hope that helps, I try to fit 3months of KD in during the year. I find during your base period is the most productive time and use for it and mentally just easier to periodize that way. After that you can try CKD (cyclical) if your able to be disciplined your body has been properly adapted in the past. If you like to do more centuries or Randonneuring, its probably for you.


People will generally have good results no matter what “diet” they try because they focus on what they’re eating. Beware of false prophets and consider the placebo effect of the stories you’re hearing. “I had the best year ever when I did X diet” equals, I rode my ass off and watched what I ate for the first time ever, it must be the diet.

Go with what works for you, exercise is much less a factor than food quality and portion control. Eat right (amount and quality) and ride lots, it’s a pretty simple formula.

And since you mentioned getting away from crap food I’ll leave you with a book recommendation. “The End of Overeating” by Dr Kessler, it’ll change your life…


I have my reasons for doing Keto, but my experience thus far (6 weeks) has not been good. My watts have dropped almost as much as my weight (I “think”. Only had virtual power data until recently). First race on Keto was today, and though I’m not all that fast to begin with I came in just over the cutoff for a DNF (the crash and subsequent road rash and bleeding didn’t help). High intensity is a struggle for me right now, that said longer rides at moderate intensity are no issue.

Bottom line:

I feel better, my blood sugar is under control and I’m dropping weight. I’m hoping I can reverse my T2 diabetes and start incorporating in natural carbs from fruits and veggies and regain some strength for next year and come back with a better power/weight ratio and be a healthier person. That’s why I’m doing it.

Do what works for you.


I lost a bunch of weight when I started cycling, then plateaued for the longest time. No difference when I got on TR. I tried eliminating a few things, maybe not stringently enough. I had a suspicion that dairy isn’t for me, eliminated it for a month and lost 2 kg in the first week or so. So I kept dairy out but the 2kg crept back in. In recent weeks I’ve dabbled with intermittent fasting, where I usually aim for 16/8 but often due to back to back meetings at work things get out of hand and I end up fasting for up to 20 hours. I’ve dropped about 4kg and they have stayed off, even during extended weekends when the diet goes out the window (or post race binging). However I’m at a plateau again. I attribute this to giving in to temptation during my eating window, refined sugars mostly. I need to HTFU and kick the habit, I bet then the kgs will fly off. Well, when I say kgs, I really want fat % to go. Which is where the IF seems to be useful… and the internets is full of that. But all anecdotal.

1 Like

Big fan of intermittent fasting, following the 16/8 split but I couldn’t get it to work too well with cycling. A good read about Intermittent fasting is on if anyone wants to read up more on it. Martin Berkhan has committed many years to the practice

I appreciate this conversation and find it interesting how polarizing LCHF can be. Recognizing that I’m an N=1, I adopted a LCHF diet two years ago to improve my overall health and here are a few observations:

  1. You need to be really clear about why you want to change your diet. If it is simply to improve your performance on the bike, there are better ways. If, however, you have metabolic issues, LCHF is the way to go.
  2. LCHF is a long term commitment. It’s at least 6-8 weeks before you are fat adopted and your body has adjusted to the new way of fueling. During this time, you will experience a decrease in power. Once you have made the full transition, however, you seemingly can go for ever at 80% intensity with little need for fueling.
  3. The criticism that LCHF negatively impacts high intensity (>80%) work is overstated. LCHF is not no carb. Your liver and muscles are limited in how much glycogen they store, and once they are depleted, you can replenish with gels, etc while on the bike without going out of ketosis. During intense exercise, insulin levels are very low and any carbs consumed will go directly to the muscle to fuel the exercise.
  4. Finally, as others have stated, electrolytes are key and need to monitored, both on and off the bike.

LCHF may not be for everyone, but if you don’t process sugars well and need to improve your health, LCHF is a great way to go without losing much if anything on the bike. You simply need to fully understand the biology and be committed.


I did keto a while. Great for weight loss but wasn’t really compatible with long rides for me. First major ride on keto I bonked bad and had to pull over for a nap.

1 Like