One month Keto going OK but no energy during 'endurance' exercise

(Floris) #1

Hi, I’ve been doing keto for one month now and its going pretty well, feel OK and lost about 7 kg (from BMI 28.1 to 25.9). Don’t feel hungry, have some great recipes and measure my blood sugar and keto levels regularly with a Keto Mojo JKI, especially in the beginning.

glucose levels between 3.5 and 5 mmol/L
ketone levels between 1 and 3 mmol/L

So, seems pretty OK from what I have read online. However … I have very limited energy for exercising. I like to do some cycling but after two weeks on keto I did a 65 KM ride and totally bonked after about an hour (30 KM). I have bonked before on carbs as well but this was absolutely next level.

Got home and measured my glucose and keto levels (twice)
glucose 3.7 mmol/L
ketones 2.6 mmol/L

After eating something (think a salad with chicken, bifi saugage, feta and dressing) I felt really tired and not very well but thought it was because of the bonking. Measured about two hours after eating my levels again

glucose 3.8 mmol/L
ketones 7.3 mmol/L (really high)

So, didn’t do any more cycling but started to do some running, no joy there eighter, after just 4 KM a really quick drop in energy and needed to walk. Normally (like a year ago) I could easily run 12 KM in an hour but OK a haven’t done a lot of exercise the last 8 months. Tried a few more runs and got up to 8 KM but always have to stop halfway for a bit of rest and stretching, very frustrating. The strange thing is also that my heartrate goes trough the roof even though it doesn’t feel like it. My max is about 195-200 but on this very short run it very quickly goes to something like180 … crazy.

OK, so today, day off from work, finally some nice weather so on the bike I went … same route (with less wind) and started relaxed. Everything OK up to 55 KM and started to feel the energy go, slowed down and did the last 10 KM really easy. Got home, felt tired but had not really bonked so great. Measured my glucose and keto again (twice) and

glucose 2.3 mmol/L (very low)
ketones 4.4 mmol/L

What the $%%#@, WHY ?.

I didn’t feel too bad but after eating some yogurt and an egg salad I started to feel pretty bad, just as the last time after cycling so I measured my glucose and keto again.

glucose 4.1 mmol/L
ketones reading said HI, that means I believe above 8.0, so crazy high

So, after this massive text … anybody knows what wrong with me and why can I not do any ‘endurance’ exercise (endurance between quotes as 60 KM cycling or 8 KM running is not really endurance). Is this normal when you start keto, am I not yet fat adapted … any help, explanation, solution would really be appreciated, THANKS !

(Alec) #2

Totally normal, and expected. You are not yet fat adapted, this does take between 3-6 months, and can take more to get truly fat adapted for endurance exercise.

But please let me tell you it is worth waiting for… the feeling of constant energy during a long run or ride is amazing once your body does adapt to burning primarily fat.

There is another mechanism going on here as well… when endurance athletes go keto, their bodies also need to develop the mechanisms to efficiently and sufficiently create the required glucose through gluconeogenesis. This allows the body to make its own glucose in the required quantity: when we exercise we use both fatty acids and glucose, and as we don’t ingest much glucose, out bodies make it instead.

So, in summary, your body is going through some major development work to change from being a carb burning athlete to a fat burning athlete (with some self made glucose as an adjunct). Trust the process, let it happen, give your body the time it needs to develop these superpowers. You will like what happens over the next 6 months.


Another thing you can try is to add electrolytes to your morning routine. As well as a T of MCT oil. Both give me abundant energy and when I miss them on a given day I notice it ALL day.

(Bacon is a many-splendoured thing) #4

Take it easy with the exercise until you are fat-adapted. It takes your muscles a while to heal to the point where they can metabolise fat satisfactorily. Your body is going through a lot of changes right now, so don’t stress it too much. Just do what you can, and soon you’ll find yourself returning to your previous performance.

Think of it this way: You did how many years’ worth of damage? So you can’t expect immediate recovery. However, you will gain your performance back soon, and many people report that, once fat-adapted, they exceed their pre-keto levels. Your explosive power may take a bit longer to recover, but it will. This, too, is normal.

(Bob M) #5

Are those blood ketones?

It takes a while to transition. For me, my blood sugar goes up when I exercise, while yours is going down. (Though I haven’t bike longer distances in a while, so it’s not a direct comparison.)

And you could always take in a few carbs during exercise if you felt you needed them.

(Floris) #6

Oh wow, sorry for my late reply and thanks for all the advice, really appreciate it. It seems that I will have to be a bit more patient with doing ‘endurance’ exercises but that’s OK. I’m losing weight pretty fast so I’m very motivated to continue, this is so much better than reducing you’re calorie intake with a carb based diet I’ve been eating for the last 50 years, I (almost) never feel hungry or have cravings with keto.

Concerning supplements, I was advised (in the book with the keto menus I use) to add supplements, especially when you start out with keto. So I use magnesium and a combination of vitamin D and K2. Also use MCT oil in the morning lately … but I don’t feel that that has a big impact, maybe should measure my ketone levels before and after to be sure if it does anything.

Did a run yesterday (same route, 8 km) and started pretty slow and made it all the way without stopping. Didn’t feel great during the run but at least it is a step in the right direction.

Thanks again for all the advice.

(Robin) #7

Oh good…. You’re off and “running’ in the right direction.

(Steven Lloyd Warren) #8

Can I post?

(Doug) #9

Indeed, Sir. Post away. :slightly_smiling_face:

(Robin) #10


(Rutledge Mc Millin) #11

I like to run about 40 miles per week. Been doing it for 14 years or so. I’ve been on keto for 2 years. Everything you described is exactly what I experienced. Heart rate higher, hypoglycemic bonking, etc. As another poster stated, surely it has to do with your body’s capacity for gluconeogenesis and restoration of glycogen levels in muscle after exercise. I stayed at it, and after many, many thoroughly unenjoyable runs, after well over a year of effort, I finally developed the ability to run long and hard on fat alone. It’s still not the same as carb-fueled cardio, but it’s fun and challenging in its own way. I still have days where I can tell my body needs to take it easy, so i mix in slow runs on those days. I have little doubt that 5 slow miles in ketosis is healthier than 10 fast miles pumped full of glucose. So I take what’s there, and I adjust my exercise to fit the diet. In short, it gets better, but it will always be different.

(Bacon is a many-splendoured thing) #12

They may or may not be needed. If you don’t see an effect, save your money. But if you experience cramps, then magnesium will help. Also, a lot of people are deficient in D and K2, so you may need them as well. They will also help de-calcify your arterial plaque as it heals and get the calcium into your bones, where it will be very helpful. Getting enough salt will also help keep the other electrolytes well-regulated.