What's going on with my HR

(Sebastien Szczepaniak) #1

Hi everyone -

Relatively new to Keto (started Jan 15th - Strict Keto < 20g net carbs), completely new to this forum but (very) experienced cyclist.
My max HR is 167bpm, endurance between 123 and 139bpm, level 3 as of 140…
For the first time today (I noticed last week as well but to a lesser extend), my HR got very fast to 140, 145, 150 bpm on a simple endurance ride (Zwift), pushing only 2.0W/kg.
Normally, at that power, I should be around 120 bpm maximum, I was flirting with 150 but completely able to talk (as if I were around 120 bpm). I was completely amazed.
Can someone explain to me if this is a sign of fat adaptation or just a regular effect of a Keto Diet? or anything else?
Worth to note that while my HR was high and my feeling was all right… power was very low and it was very difficult to push more… I was abnormally tired with a feeling of no power in legs…
Thx a lot beforehand


Fat adaptation. Also, increase salt and electrolytes. Worked for me.

(Sebastien Szczepaniak) #3

Thx. When you write fat adaptation, you mean after fat adaptation my HR will resume to former level (when fat adapted) or this is my “new HR range” (Being already fat adapted or not) ? - I have supplemented during ride with electrolytes as I felt cramps were about to come … thx a lot


Many people feel this while starting to become fat adapted. It’s called the “Keto flu”. For me, electrolytes were the cure. Others struggled with it longer. It does go away

(Sebastien Szczepaniak) #5

You referred to cramps right? And for the HR, will this resume to previous levels after adaptation?


Cramps, odd heart behavior, hot flashes, fatigue, and more. The Keto flu takes different shapes for different people. It is a transition symptom. The electrolytes balanced my heart rate and stopped my hot flashes and fatigue. I had very little in ways of cramps myself.

(Sebastien Szczepaniak) #7

Thx much


@seb I’ve noticed that my resting heart rate is lower while I’m on keto. I went off for a while around the holidays and my resting heart rate rose from about 64 to 83.

(Sebastien Szczepaniak) #9

Hey Tyler

Thx for feedback.
Did a new ride today and again my HR was way off what it was during my last 20 years :slight_smile: basically 10 beats up vs. what ti used to be at endurance level.
My resting rate though is only 2/3 (around 40 bpm) up vs.before Keto.
Anyone else believes it’s just transition phase going on and it will be back to normal after a while (a while still needs to be defined right?).
Is fat adaptation on its way?


I’d go get checked out. See what your electrolyte levels are.

(Windmill Tilter) #11

Elevated heart rate is fairly common. It’s typically noticed in the form of an elevated resting heart rate though. Usually it’s an electrolyte thing. Have you been supplementing electrolytes? Take a look at Brenda Zorn’s “keto-ade” recipe here on the forum. It’s helped heaps of people rebalance electrolytes in the beginning and it’s dirt cheap.

The recipe is just Himalayan sea salt, and magnesium citrate. It’s usually a magnesium deficiency responsible for the heartrate stuff if I remember correctly. You can buy magnesium citrate at the grocery store or pharmacy where they sell laxatives.

It might resolve the issue in a few days, or it might not. It costs about $1.00 to find out.

Fat adaptation is a continuum. You were already on it before you even started keto. You’re just further along it now. If your goal is to reach the level of fat adaptation achieved by elite endurance athletes like the folks that run 200k races, it’s going to be a while. Here is a good book on the subject by two of the most respected researchers in the field.

When most people refer to being “fat adapted” here, they’r talking about being able to walk a dog for a mile with good energy levels. Your goal is very different. If you want to see what’s possible with respect to fat adaptation, take a look at this journal article on the fat metabolisms of keto ultra-endurance athletes vs high carb ultra-endurance athletes. It’s by the same authors as the book linked above.

(Windmill Tilter) #12

These two threads in the cycling sub-forum here also talk about elevated heart rates at lower power outputs, and higher lactate thresholds:

(Sebastien Szczepaniak) #13

Thx much @Don_Q for your perspective and links.

I knew already the art and science of low carb performance book which I’m going to order soon.

The study you provided is absolutely fascinating, fact that compared to trained ultra-endurance athletes consuming an HC diet, long-term keto-adaptation results in high rates of fat oxidation, whereas muscle glycogen utilization during and after a 3 hour run are similar, is really promising.
I guess next step would be to really understand absolute performance difference and if better for LC between the 2 cohorts (which is clearly not studied here) but anyway this gives hope and courage to follow on the Keto adaptation I’m going through.

Question for me is how to accelerate fat adaptation in order to get rid of these pathetic performance level I’m having right now… knowing that I am already at 20g of carbs per day… maybe this is just patience and consistency that I need here.

Anyone else having a perspective here?