My continuing low carb experience – will ketosis make me a better cyclist?

Cycling Ascents - Accommodation and Training Camps at the foot of Alpe d'HuezIf you’ve not seen the previous blog posts I’ve written on my thoughts and experiences on a low carbohydrate diet, then this would be a good time to check them out!  I’m going to go into some depth in this post so if you’ve landed straight here you might be better to come back after reading these:

Exercise without Carbs

Cycling on a Low Carb Diet Update

So….before we start I thought it might be useful to define some terms I’ll be using or you might have come across in case you are not familiar with them.  If you are, skip ahead!

(Nutritional) Ketosis – the state your body is in when it is producing ketones (above a certain level).  Usually achieved by restricting carbs to between 30 – 50g per day (could be more or less depending on the person and their level of exercise volume & intensity)

Low Carb High Fat Diet (LCHF) – any diet where carbs are generally restricted & replaced with additional fat (protein stays the same), but without the carb restriction down to the levels to promote nutritional ketosis.

Ketones (or ketone bodies) – a by product of burning fat (so the more floating around your body the more in ketosis you are)…and the preferred fuel for your brain when in a depleted carbohydrate state

(Diabetic) Ketoacidosis – a bad thing!  An condition potentially affecting diabetics when blood sugar and ketone levels both get dangerously high (not possible in non diabetics). Related to but not at all the same as ketosis…if someone tells you ketosis is dangerous then they are probably mixing it up with this.

Keto Adaption – when your body has been in nutritional ketosis long or often enough, and has produced sufficient enzymes to increase fat utilisation levels & your muscles have become efficient at using these increased levels of fat as fuel.  In real tems you are at the point where athletic performance returns to ‘pre ketosis levels’  Around 1 – 2 months as a rough estimate, but probably varies based on how ‘strict’ you are with keeping the carbs low.

Keto Flu – the flu like symptoms when first entering into ketosis. Your body & brain’s way of saying wtf do I do with this new fuel, and where have my carbs gone???  Usually over within a week or so, depending on how hard you reduce the carbs down.  Symptoms are often made worse due to lack of hydration & low sodium levels.

Z1, Z2, Z3, Z4, Z5 – nothing to do with ketosis or diets, but shorthand for training zones as defined by Andy Coggan.  Z1 is recovery pace,Z2 is endurance levels, or steady riding, Z3 is tempo (think challenging group ride pace), Z4 is threshold, and Z5 VO2 max.  Roughly.  There is more to it than that, but hopefully you get the idea.

I’d also like to state that while I’ve learnt a lot about low carb diets and ketosis over the last 6 months and the effect it’s had on my own athletic performance, I’m not an expert and definitely not a doctor.  If you are thinking about trying ketosis or a low carb diet out, I would very much recommend it (you’ll see why just below!) but I encourage you to do your own research, and if you have any existing conditions then to definitely check things out with your doctor or a medical professional.  Keep in mind though that while ketogenic diets are getting more popular they are still very much contrary to the ‘traditional’ nutritional advice so the response you get may not be 100% positive, but use it to make you own mind up along with whatever research you have done into your own personal circumstances to determine if it’s for you or not.  Get out clause / ass covering over 🙂

So, before I get to the question you want hear an answer for, why should you consider trying out ketosis? ie what will be the positive effects?

  • Potential weight loss, while not affecting energy levels for effective training. This is a big one! Balancing hunger, calories, energy levels and a training schedule on a traditional low fat high carb diet is a nightmare….on a low carb high fat diet it’s a relative piece of cake!…but you can’t eat the cake… 🙂
  • Less reliance on high carbohydrate energy products (which cause gastric problems for a lot of people, including myself)
  • Ability to exercise for long periods with minimal fuelling…less chance of bonking / hitting the wall etc
  • Concentration levels can be maintained for longer…no brain fog from being in a low blood sugar state
  • Consistent energy levels throughout the day
  • Feeling just as full of energy after a long ride as before it!  For example not needing to crash out on the sofa after getting back from a tough ride…handy for anyone who’s not a professional athlete.
  • More consistent mood
  • Better quality of sleep…another big one.  I personally think sleep is the most important aspect of recovery, and recovery is often woefully neglected
  • Less oxidative stress for a given level of exercise (compared to when consuming carbohydrate energy products)…this means quicker / easier recovery as you do less damage to your body in the first place

So, this sounds great huh?  Of course, as with pretty much everything in life, there are two sides to every story.  Here are some of the things that aren’t so great about the diet:

  • Learning what you can and can’t eat – as this is probably a big dietary change for most people, it takes time and effort to discover and learn new recipes, buy in all the different products you’ll need, and unless you live alone or convert you whole family you’ll probably be cooking two separate meals each time you eat (or at least cooking one meal and adjusting yours to include more fat).  There are plenty of resources out there to help however, and this is a good one to start with.
  • Following on from above…..Social eating.  It’s possible but not always easy to follow a LCHF or keto diet while out at a restaurant, and I wouldn’t even try if I was invited to someone’s house for a meal (although of course it’s probably ok to ask if you can pass on the potatoes).
  • No more beer….or French bread…or ‘insert your favorite carbohydrate rich product here’.  As you are either in ketosis or not, you can’t ‘cheat’ with this diet, and definitely not in the early stages.  In one way I think this is a good thing….sugar is remarkably addictive and it took me a good couple of months before I didn’t feel the urge to eat something sugary whenever I saw it. However now I look at a piece of chocolate in exactly the same way I’d see a big chunk of cheese…it’s just food.  It wasn’t like that 2 weeks into a LCHF diet I can tell you!  But tough it out and it will be worth it…
  • Your cholesterol levels could increase.  This is a complicated subject, so I’ll just say that for most people cholesterol improves…as shown by this study, but for a small number (myself included) your total cholesterol levels can increase.  I’m not personally concerned however, as my ‘good cholesterol’ (HDL) has increased, my triglyceride levels are low and while my ‘bad cholesterol (LDL) is higher than I would like, it’s the particle size that matters, and LCHF diets typically increase LDL particle size (which is good)… if you are still with me I think I’m going to be ok!
  • Aside from dietary implications, you might lose your capacity to exercise at very high intensities, such as sprinting, or short efforts above VO2 max for example.  Early on in the diet, when you are still adapting, anything above tempo (a strong effort but not really fast) feels terrible, but then as time goes on everything goes back to normal…with a little bit taken off the top end. Having said that though, this study showed that long term LCHF athletes had just as much glycogen stored in their muscles and replenished it at the same rate (despite not eating carbs) as the high carb athletes….so you might be fine!

So if you’ve got to this stage and think, yes, on balance sounds good, should I try it out?  Then I’d say absolutely, give it a try.  Especially if you are:

  • a long distance athlete (ie take part in events that take 4 hours or more)
  • are struggling with carbohyrates, or have the feeling that they are doing you no good
  • have swings in energy levels or mood (ie do you often feel you would like to take a nap early afternoon?)
  • would benefit from losing some weight, but don’t want constant hunger and lack of energy
  • not someone who needs a race winning sprint

If you’d like to learn more about ketosis and the effect on sporting performance, I’d really recommend this book by Volek & Phinney.  They are at the forefront of science in this area.

Now I’ve covered the bigger picture, how is it going for me?  The last blog post I wrote was just before Christmas, and I wasn’t convinced I was going to get through without being tempted back to the dark side (my traditional high carb diet).  It went remarkably well however, and while I did of course eat many things that meant I was nowhere near ketosis, I generally stuck to avoiding the high concentrations of carbs (except for the odd desert!) and then afterwards settled back into a LCHF diet, a bit more relaxed than the ketogenic diet I was trying to stick to prior to Christmas.  This worked well for me in the off season, especially as I wasn’t doing much exercise at all (our new project kept me off the bike for most of Jan – April).  However I decided to try and get back into Ketosis in April, to see what effect it would have on the long rides I typically do when getting back into base training.

The first thing my engineer brain thought was ‘well how can I measure that I will actually be in ketosis?’  Some people are happy to restrict their carbs and, quite rightly, assume that they will be in ketosis.  But being a precise kind of guy, I have to know!

I’ve used Ketostix before – which are great when you start out, but less accurate as time goes on (they measure the waste ketones in your urine, however after you become keto adapted your body disposes of less and less of them…as it finds a balance on how many to produce, and the body becomes more effective at actually using them as an energy source.)  I thought that my 2 months keto and then 3 month LCHF would potentially make them useless.

An alternative is blood monitoring.  Using the same device that diabetics use to measure blood glucose levels, you can buy strips specifically to check your blood ketone levels.  While very accurate, they cost a fortune!  So I plumped for option 3….

A Ketonix – a device that measures the acetone (another by product of ketosis) in your breath.  The advantage of this device is that it’s a one time investment – no strips required, so you can test as often as you like!  It also tells you in real time how much you are in ketosis (the blood test shows you how long / much you have been in ketosis as the ketones in your blood are effectively an energy storage facility by your body, but you could have a high value, eat a doughnut and be out of ketosis while still having (temporarily) high blood ketone levels).  Therefore using the breath test method (Ketonix) you can in theory find out which foods might kick you out of ketosis, how many carbs you can eat after exercise while staying in ketosis, etc etc.  Sounds perfect! Unfortunately, my Ketonix doesn’t work.

I know this as after many weeks of trying, and sticking to 30 – 40g of carbs per day, I still wasn’t getting values showing I was in ketosis, and often getting a zero reading.  So in the end I bought a blood monitor anyway, which over the period of a week showed I was definitely in ketosis, while the breath monitor was still showing me a big fat zero.

So, after an email to the vendor, I have a replacement on the way which with fingers crossed will work this time!  Note there is a common mistake made by people using the Ketonix regarding the breathing technique….it needs the very last bit of air in your lungs, which can be hard to get right.  I was literally turning my lungs inside out however (I once got cramp in my intercostal muscles I breathed out so far!) so I’m fairly confident I didn’t make that mistake.

Measurement aside, the diet is generally going very well for me.  Compared to my last update my cycling performance is right back to where it should be…perhaps even better – which I’ll talk about more later on (better compared to a high carbohydrate diet, and for the amount of cycling I’ve done so far this year). The sluggishness I sometimes felt in the early stages of the diet before or during exercising is gone, and now I’ve done some longer rides (just with electrolytes) I can clearly state that energy levels are not an issue (the legs on the other hand need a little more work – I’ve not done much riding yet this year compared to normal).  One key factor I feel has really helped get the most out of my performance on this keto diet, is ensuring I am getting enough salt prior to exercise.  It’s another aspect of the diet that is ‘against current advice’, but when in ketosis your insulin levels are very low, and it’s insulin which signals to your body to keep hold of salt.  So in ketosis (or for a lesser extent on a LCHF diet) you need more salt to compensate for the fact that more is just passing straight through your body.  Having your sodium levels wrong can create havoc with your endurance performance (low levels will restrict your blood volume as your body tries to keep the concentration in a certain range).  Obviously if you have high blood pressure already you will need to be careful about this, but if not, I’d keep adding salt to your diet based on feel.  A drink made from a beef stock cube will really boost salt levels, and if you have one of these an hour or so prior to exercise it can really make a difference.  Salted mixed nuts are now my cycling ’emergency snack’ rather than gels or bars, which I’ll occasionally take a small amount towards the end of a really long or tough ride.

Another good tip which can give an energy boost is the use of MCT oil.  This is oil that has been refined (yes I know processing is not good) to just leave the medium chain triglycerides (C8 is the best, followed by C10) which are most efficiently used by your body during ketosis.  I’ll typically have this in the morning with butter in my decaf coffee  – look up bullet proof coffee…you can use real coffee for an extra fat burning boost…I’m just not very good with caffeine unfortunately.  Now I’ve been in ketosis a while I seem to digest it pretty quickly, so sometimes have one 1/2 hr or so prior to exercise for a boost in energy levels.  Normally fat prior to exercise is a bad thing as it’s difficult to digest (if you are on a traditional diet), but I think the combination of the medium chain oils and being keto adapted means it goes down just fine!

Other potential energy sources that I’m yet to do much experimentation with (but it’s in the plan) are:

Exogenous ketones – these are synthetic ketones (exogenous means produced outside the body) which are usually sold as a dieting aid…but potentially give a big increase in blood ketones hence energy levels

Vespa – a really interesting looking product that stimulates your body to produce more of it’s own ketones (using peptides extracted from wasps!) I’m keen to try this one out – if it’s good enough to help Romain Bardet win a stage and come second overall in the TdF then I’m willing to try it!  More to follow on both of these…

So to finish (sorry for being a tease :)) I’ll get to the original question..has being on a keto / LCHF diet made me a better cyclist?  Well I did a training ride the other day that’s a standard ‘long-ish’ test for me – 100km (give or take) with just short of 1600m climbing.  I went pretty hard, especially given it’s the first time I’ve done it this year.  Rather depressingly, power numbers while climbing were well down compared to previous years, but I did expect this as I’ve done much less riding this year – about 80 hours so far this year compared to about 180 at the same stage last year…and much less higher intensity work.  So that was to be expected, and I did wonder if I was setting myself up for trouble – going hard, longer than usual, first time of trying this year, not enough miles in the legs…all the standard ingredients in a recipe for disaster called bonking.  But I continued to feel ok so kept going.  The first thing I noticed was that despite the lower power, the lower weight meant that the climbing speed wasn’t too bad.  Also, sections in between climbs where I’d typically have to back off (my normal thinking is there’s no point burning your matches when on a carb based diet on the flats…I want to save more energy for the climbs, as I live in the French Alps) I felt that I could still keep a relatively good pace…and it didn’t appear to be affecting my overall energy reserves.  It felt like an upper zone 2 endurance pace, which before I changed my diet I could keep up for a long time but would ultimately be using some of my energy at a slow rate, was now mine to use for free!  This is possibly because the diet has bumped up the intensity I can ride at while still maintaining 100% fat burning…I’ve no idea of the numbers as I’ve never done the relevant testing but my guess would be that in the past, even when fit I was probably something like 75%/25% carbs vs fat at that intensity (upper Z2), so even though 25% of not much is not a lot of calories burnt, over time it still depletes your glycogen reserves.  Riding on the flat or downhill at this pace felt just fine even at the end of my ride, where typically everything normally feels bad (just different levels of bad!).  During the second half of the last climb of the day I did feel like I was starting to lose strength, but 20g of salty nuts later I felt much better.  Whether it was the salt or the small amount of carbs (I’d been riding between Z3 & Z4 on the climbs so will have been using glycogen) I don’t know, but it picked me up and I finished feeling pretty good, especially for the effort I’d put in, and the fact that I’d gone way harder than usual for a first effort of that type for the year.  So how did I do?  Well despite the fairly poor power (which gives me something to aim at improving), and lack of training hours I got round in a shade under my best time ever….which pretty much blew me away.  I was purposely trying to avoid carbs during the ride in order to test myself, but would not do this in a race situation so even with my current relatively poor level of fitness there is scope for improvement.  I was riding alone so there was no drafting effect, & given the amount of climbing the weather / wind doesn’t come into it too much (although weather conditions were pretty good, so this might have helped a little).  I was probably also unconsciously pushing a little harder maybe (as I wanted to be faster) but seriously didn’t realise until near the end of the last climb that I was on for a good time.

So, for one test in my own personal n=1 experiment, the result is a (totally unscientific)win for ketosis! Perhaps a little more testing needs to be done :), but it’s started in the right direction.

View up the Col d’Ornon – the last descent of the day of my 100km test loop


18 Replies to “My continuing low carb experience – will ketosis make me a better cyclist?”

  1. Kevin,
    Super excited to have found your site! Started Keto three weeks ago and have been extremely frustrated with my power outputs on zwift. All the sudden I cannot hang with the normal group of riders I usually ride with. I am hopeful that I turn the corner in a few weeks like you have written about getting back to “normal power.” I was worried that this was the new norm and have almost given up but after reading this I am gonna go on for the original three month trial I was going to do! If I keep getting dropped come spring I might need to head back into a modified carb only for specific rides and stay low carb when not cycling. Planning a trip to France in summer of 2019. Hope I can meet you!

    1. Nice to hear from you Matt. You are probably in the toughest period right now and you are asking your body to perform just as well as it has in the past but with a completely different fuel source. If there are long hard efforts in the rides you are getting dropped on try taking a small amount of carbs part way through the effort – if you are riding at threshold intensities or higher for more than 10 – 20 minutes then your body will be able to use them without necessarily kicking you out of ketosis. But I’m afraid that you will likely see a drop in performance in your higher intensities for a good while to come…ketosis is better suited to low to mid intensity efforts, and this is even more true prior to you becoming fat adapted. Good luck and let me know how it goes for you!

      1. Thanks for the reply Kevin… I might need to rethink keto but at least it’s winter! Most of my rides are with a group that is faster than me and last for 1-2 hours of pretty intense effort. Today they were keeping a 3.5w/kg pace and I lasted maybe 15 minutes and told them to go on. Old me probably could have hanged. Keto me no way! Confused but will stay on course. When you say take a carb during effort. How many grams and what kind of source would you suggest? I fear I burn through my glycogen stores so fast and then power just suffers the rest of these rides. Only week 4 though so… like you said, probably a very tough portion of training!

        1. Unless your FTP is north of 4w/kg then I’d say that these rides are too tough for 4 weeks into ketosis…if you can only manage a 15 minute effort which you would have previously kept up for an hour or more indicates to me that your glycogen levels are low (normal for someone just into keto)…and as your body is still burning it at a relatively fast a rate you run out of steam much more quickly (also normal for the stage you are at!). Over time your body will get better at creating your own glycogen, and you will burn it more slowly for a given intensity – so you’ll get back to where you should be, except for the hardest efforts .I’d just keep it at a lower intensity for another month and then see how the faster rides go after that. Can I ask why you are trying a keto diet?

          1. Hey Kevin,
            Intrigue more than anything. My last ride of the fall was a 150km group ride at a pretty good pace. Many things probably contributed (x bike with different gearing, faster pace, tough workout day before) but I bonked with 50km left. I realize this could have been a one off but this got me thinking about keto. Then I read Attia’s self research numbers and was pretty fascinated by them. Ultimately though I am terrible at eating. I’m an anesthesiologist and I am to go go until I would get home. Woulldnt eat breakfast, wouldn’t eat lunch, then would come home snack on some high sugar food, then eat some high carb meal. So… keto seemed good bc I could get away with this “fast” without it being so detrimental to my health. I decided to give it a try over the winter months. FTP pre keto was 245, FTP yesterday was 215. Pre keto weight was 74.5 now I’m 69. However that 69 is probably still elevated bc of some weight training. I think I just wanted to try it out. I will most likely go back to introducing some starchy carbs come spring and become more targeted. I want to be able to hang with my friends and they are getting stronger of the winter while I’m getting weaker. That weakness is relative obviously bc of my body going through some changes. The question is would my power jump back up if I started eating carbs again or even be higher? My workouts haven’t changed which means after 5 weeks on a normal diet I probably would be stronger. Am I still building muscle even though I feel weaker? Is it just cells changing and their ability to utilize different macronutrients, or did I actually lose muscle, strength, and the ability to hang with these guys. No doubt being 6 or 7 kg lighter I will be faster as you found on your hill climbs. What I need to figure out is… is that 10–12% drop in power (now) worth that 6-7 kg loss in weight? The answer for me today is NO. I would rather have the power. However if that ftp returns at month 2-3 on keto to what it previously was and continues to climb then I think I would continue keto/targeted keto bc of its health benefits and everything else. Wow long answer to your question which could have been summed up as: I want to be able to go long, be strong, stay light, and be healthy! Kevin would you want me to send you emails instead or are you okay with these dialogues being on your blog. I do appreciate your time and wisdom. I also believe we will one day meet in person which is super cool! Thanks,

          2. Hi Matt, First of all if you are happy to keep going with this discussion on the blog them I am too! I think it sounds like a keto diet would suit your lifestyle, but you are unsure if it’s going to work for you from a sporting performance point of view. First of all, I think that worrying about FTP test results is probably the worst thing you could do right now – I presume you did a 20 minute test and that’s probably the power / duration that’s taken one of the biggest hits as your body tries to adapt. Putting your latest FTP numbers to one side, to me working out if it is right for you will boil down to a few points:

            a) do you feel better on the new diet? 4 weeks is long enough that if you’ve been restricting your carb intake sufficiently, you should be well into ketosis, and feeling the energy level and other benefits.
            b) is feeling strong 4 hours into a z2/3/4 ride more important than your FTP?
            c) do you struggle to get to the weight you want to be on a carb based diet?

            If you answered yes for all of the above…I’d personally live with the lower FTP (which I’m sure will come back with time) and stick with it. If you answered no, then maybe keto isn’t for you. We all have different levels of carb tolerance, if you are ok with carbs, you might not find the benefits enough to outweigh the disadvantages. Keto clearly seems to fit your lifestyle, you need to decide if it fits with your cycling ambitions. But don’t forget that it’s a long term commitment – I haven’t been monitoring my FTP as I’ve not really been training hard while on keto but based on feel I think that it’s taken me more than 6 months to get my 20 minute power back (rather than the 2 – 3 months you mention…but it could be different for you!)

            Assuming you are going to stick with it – to answer your question about re-introducing carbs, I’d hold off for the time being. I think that at the stage you are at it will be sending mixed messages to your body. Experiment by all means with carbs when you are keto adapted, but it sounds to me you are not there yet and I think that I’d personally swing more the other way – restrict the carbs more to force your body into making it’s own glycogen. Initially I had to be lower than 30g (ideally less than 20g) of carbs a day to get into ketosis, and build up enough blood ketones to start to feel stronger on the bike again. It sounds to me like you are running a little on empty with regards to glycogen reserves, and if you provide more for your body through food the less likely it is to make the switch to producing it’s own (which is the goal). I found that the cold turkey approach worked for me – I also weighed the food I ate and put it into a spreadsheet – yes it’s a pain, even for an engineer 🙂 But I found it essential in order to get a real idea of the amount of carbs I was eating – until you do this is can be hard to know for sure you are in the correct range.

            Lastly, you shouldn’t have any problems from a muscle / strength point of view – ketones (as well as the hormonal changes ketosis causes in your body) are known to ‘spare’ protein:


  2. Hey Kevin, probably should have read this earlier. Wife is away for the weekend. I have four kiddos and rode for an hour after putting the younger two down for a nap. Pretty good effort but pretty low power. After taking one to a birthday party the other three wanted some Mexican so we went. On the way I felt off. Maybe dehydrated, probably electrolytes were out of whack but also felt hypoglycemic which shouldn’t be the case. I being very disciplined have probably gone less than 10 grams a day of carbs. I use the Senza app. Well tonight I ordered a coke and had a few chips and salsa. These being the first bad carbs I have eaten in 5 weeks. I only have the urine strips and checked which showed I was definitely in ketosis still. I need to get a blood monitor bc. I would like to play around with on days I do a hard ride figuring out how many carbs i can push to help me on the bike. Yes I would answer yes to your questions. It does fit my lifestyle! I will fight the urge to get that ftp up, all the while continuing to train for nothing in particular. I do think a little more carbs than the 10 or so I have been consuming could help replenish the glycogen quicker. I’m gonna get that blood monitor and play around with some pre prandial post prandial levels before and after certain bike efforts while consuming some carbs and other times more but never to push myself out of ketosis. Like you said some people respond differently. Question. Is the goal okay to just stay in a Ketotic State. If one can consume 200grams of carbs and remain in ketosis is that okay to do? I think that there is still a possibility that one could remain in ketosis and still have productive gains from carbohydrates on the bike in this time of transition to a well oiled fat burning keto utilizing machine. I need to shift focus away from production. This is difficult however being so type A. I will be in touch! Thanks Kevin

  3. Hi Matt – with regards to replenishing glycogen, in my view the goal on ketogenic diet is to achieve this through mainly through gluconeogenesis (not to be confused with glycogenolysis), rather than eating carbs.

    Basically the first process (gluconeogenesis) is the body’s way of creating new glycogen from non carbohydrate sources like protein, fatty acids, and lactate. This is what you want your body to be doing on a ketogenic diet in order to get your muscle glycogen levels up. It makes sense to me that the efficiency or scale of this process could take time, and that perhaps in your situation you are asking too much from it at your stage in your dietary change by continuing with high intensity workouts (this last sentence is conjecture on my part!)

    The second (glycogenolysis) is a non desirable process which can happen when you run out of stored carbs and are not on a keto diet, as it provides glycogen to your body by taking it from your liver & muscle glycogen, and then (even worse) by breaking down the protein in your muscles.

    I know that it has been shown that people who exercise can tolerate more carbs and still stay in ketosis – and if you get a blood monitor (definitely a good idea) you can test this out and see what level of carbs you can take immediately after exercise and still stay in ketosis. I have no idea if by doing this you will compromise the gluconeogenesis process or not….or even the rate of keto adaption. I’m kind of an all or nothing person and took a cold turkey approach…which worked for me (as I was willing to accept the lower performance at higher intensities during my off season training). Now I feel like I’ve got as much glycogen as I need – like these guys:

    But I admit it’s taken me a long time (getting on for a year!) Once past the initial adaption, I definitely think there is a place for increased carbs – I’ve used them sparingly in the last few 4 hr plus races I’ve done and it’s worked well. But that’s the issue – I don’t know if increasing your carbs intake now will compromise your keto adaption (obviously assuming that you are still staying in ketosis by monitoring your blood levels…as I wouldn’t rely on the urine sticks for the level of carb / ketosis juggling you’ll need to be doing), but I’d certainly be interested in how it works out for you.

  4. So the more I read I think I probably should just change it up a bit. With four kids I hardly ever have time to go on 4 hour rides. Those might happen one weekend day a month, but typically it is intense effort for 1-2 hours. HR not dropping much below 170-175. I have never tried adapting while on keto to a decreased pace and longer distance with a low heart rate. There in lies the problem and frustration bc I want to be able to put out that maximum intensity but don’t know if I want to wait 2 years to get there. I don’t know if that a cycled keto diet works. Like you I am usually an all or nothing type of person. At this point confused though bc I like not having to worry about eating and the energy level I am at while not on the bike. I like the leaner look. There are a ton of positives, but it overwhelms me that I can’t hang with my buddies anymore. Gotta figure this out. Might mean getting out of ketosis and watching what I eat which I think is impossible not to do at this point. Still eating high fat moderate protein but increasing those carbs to find that sweet spot where my intensity level can be high for that 1.5 hours and feel strong while doing it. There has to be a happy medium. So Kevin on these 4 plus hour races are you holding back. Is it possible you burn through your glycogen on a tough climb and then have to bring it down until you can get levels back up? I’m lost

  5. Hey Kevin,
    Hope your well! I think I turned the corner which has been encouraging. Power is up. I have been messing around with the blood monitor. I need to start increasing duration of rides though bc I have kept it under 1.5 hours at this point. I started some interval training as well. How are things for you?

    1. Hi Matt,
      Good to hear things are going well, and you are getting your power back! Sounds like the blood monitor was a good investment for you. If your intervals are feeling ok then that’s a great sign that you are producing the glycogen you need yourself (as well as probably being more efficient in burning it).
      I’m good thanks – I’ve been focusing on triathlon lately so leaves less time for the bike, but I find that the measured, long duration efforts really lends itself to the benefits I get from a keto diet (I’ve done a 1/2 ironman recently, during our holiday in New Zealand….hence the lateness of the reply from me!)

  6. Im glad you wrote this blog so I dont have to. very similar journey but Im a bigger cyclist, usually around 100kgs. Took me about two months to stabilise my cycling performance from a power point of view. and now yes, I seem to be bonk proof. I can cycle 150k on a cup of tea which would have been impossible for me in 2016. I also dont really miss the carbs now, and on the odd occasion when I take down too many (friends dinner, christmas) I feel bloated and horrible for a couple of days. That said, I now do eat carbs when Im looking for a big effort on the bike – it feels liike having two engines and is very promising. Im experimenting much more with this ths year. Did a long ride today and took in a reasonable number of carbs before the ride. it felt great. My as yet untested theory is that this might be the way forward – i.e. carbs are fine if you are frying them off fast. Other than the cycling, I shed fat on LCHF, and generally feel better. I like it.

    1. Hi Paul, good to hear from other keto cyclists out there! Sorry for the delay in replying (I’ve been away for a major holiday in New Zealand recently amongst other things). I too suffer when I very occasionally indulge in carbs…I call it a carb hangover and I’ve found the best way to beat it is to get out on a long ride and burn them off! I’m also having success with limited carbs in important training sessions / races, but find that my tolerance of them is even worse than it used to be so have to be really careful not to over-do it,otherwise I get some serious stomach / intestinal cramps (but that’s probably because I have low level colitis anyway). But yes, it’s been noticed by quite a few people that as long as you are running fairly high intensities or long hard efforts (that result in your body really cranking out the ketones) that replacing carbs works well… even though we are burning much more fat we’ll still eventually run glycogen levels low without some way of replacing them (this study suggests that while we burn carbs at about half the rate of high carb dieters, the rate our bodies produce glucose during exercise is the same: So putting some back when needed is a good strategy…..

  7. Hi Kevin. 4 weeks in to keto and finding the same results as you! People claim keto is good for cycling but it seems these people don’t do any threshold efforts on the climbs, haha! My power is down but I’m hopeful of it’s return after reading your blog. The blood monitor has been extremely useful for learning how many carbs I can have whilst staying in ketosis so I think I’ll be using that to balance my energy stores before a race (with a few carbs I think). Luckily, I race cyclocross so experimenting in the summer hasn’t spoilt anything. Keep us up to date on your progress and thanks for sharing.

    1. Hi Matt, thanks for posting your experience with the diet. 4 weeks in is really early days in my experience so keep with it if everything apart from the power levels is working for you! CX might be a tricky one to get the most out of a keto diet however due to the power profile you’ll need (lots of repeats of high intensity efforts with threshold in between). If you are riding at VO2 max for a significant portion of your racing you might find that the power you can push is a little down compared to a traditional carb diet. But if you really get well adapted you might find you can make those glycogen stores last longer. Good luck!

      1. Hi Kevin. Thanks for your reply. I’m definitely going to stick at it and see where I can get. I agree that the CX looks to be a challenge but I will experiment with adding carbs on race day and see what happens! Once I’m “adapted” (I hope it will be obvious) then maybe a cyclical ketogenic diet may be useful. I certainly look forward to my next sportive where I hope to sail past all the feed stations! Thanks again for sharing your experiences, it’s really interesting to learn from other people. Keep up the good work.

  8. Hi Guys ,
    Heres my story about keto .
    About 6 Month Keto , before Keto FTP 213 , Weight 71 .
    After keto FTP 135 , weight 61.
    Any idea how for increase FTP

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