Tag Archives: keto flu

Going Ketogenic and HRV

Inspired by a fellow Quantified Selfer at our recent Denver QS Meetup and motivated by multiple guests on Damien Blenkinsopp’s excellent Quantified Body podcast I decided to switch from eating vegetarian to eating ketogenic. And always interested in heart rate variability (HRV), I wanted to look at the mix of going ketogenic and HRV.

I won’t go into too much detail about ketosis and its reported benefits. At a high level you switch your body over from sugar (glucose) burning to fat burning (ketones). To do this I was going from a very carb heavy diet to one that severely limits carbs and moderates proteins while ramping up fat. Imagine my long suffering vegetarian wife’s surprise when she came into the kitchen to find me chomping on bacon with a coffee full of butter.

One element of the switch involves a state called “keto flu” which is the body suddenly finding no carbs available and sending pretty clear signals to the brain that its time to find some carbs. Proponents of the diet tend to downplay the effects calling it a euphemistic “short term discomfort” but I have to say it felt like I had been hit by a truck.

Going Ketogenic and HRV

Me no like keto flu

Of course being a Heart Rate Variability (HRV) enthusiast I had to check the impact of the transition on my resting heart rate and HRV.

My Question

What impact would the transition to ketosis and its associated “keto flu” have on my HRV? What did the load on the body look like?

What I Did

I measured my resting heart rate and HRV for three weeks during the transition to ketosis. I was also measuring my glucose and ketone production so could verify when the transition was complete.

How I Did It

I measured my heart rate and HRV reading using a Polar H7 heart rate belt that was sending data to Marco Altini’s Heart Rate Variability Logger four times a day. I would take a reading first thing in the morning, later in the morning after traveling to work, after lunch and before bed. Once each morning I would use a glucose meter and a Ketonix breath ketone analyzer to check the trend in my transition to ketosis. Toward the end of the period I used a Precision Xtra ketone meter to verify with surety I was in ketosis.

What I Learned

Transitioning to ketosis is a real butt kicker of both mood and heart level activity. First my mood went very dark and on day two I almost tore my car’s steering wheel out of its moorings when I couldn’t find a parking space. Keto flu for me was like a bad hangover mixed with a flu-like dizziness. For me it took two weeks to transition to ketosis.

At the physiological level my resting heart rate over the period showed a large amount of load on the body. You can see from the graph that my resting heart rate popped up almost immediately. In the middle of the transition I was getting a readings of 85 to 93 Beats Per Minute (BPM) and that was unusually high. I am usually in the high 60’s to low 70’s.

Going Ketogenic and HRV

HRV showed a similar story. The four readings through the day showed that my HRV was lowered in the early day readings but tended to be similar in the later day readings.

Going Ketogenic and HRV

HRV has a circadian rhythm. As with our energy levels, it tends to drop over the course of the day. You can see that in the baseline. The slope of the curve was still negative while in the transition, but the slope was greatly reduced. I would have expected the slope to be the same and the lower start point end with a lower end point, but that was not the case. Perhaps the body has a baseline beneath which it won’t drop based on health and when in load the impact is in the beginning of the day when the body should be able to relax.

From an HRV perspective it looks like transitioning to ketosis has a similar effect on the body as being overtrained as an athlete.  The body’s Parasympathetic Nervous System seems to be less capable of putting the brakes on the system and bring the body to a relaxed state.

The happy news is that once through the whupping you get from keto flu the benefits are as advertised. I dropped 12 pounds and feel great. I have a lot of energy and feel very clear of mind. All the better to conduct more studies in the future.

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