High heart rate during a ketogenic diet

This is NOT a discussion on whether a keto diet is a good or bad idea. It is simply something I told a friend I would try with him for a short time during my off season. With that said, my heart rate seems to be much higher during my workouts. I know there are a lot of other factors such as less volume and still recovering from an ironman, but I was curious if this is normal for someone on a ketogenic diet?

Expected. One of the negative consequences of inadequate carbohydrate intake is a reduction in plasma volume, and hence reduced cardiac filling pressure and hence reduced stroke volume. Your body attempts to compensate by increasing heart rate, but cardiac output still tends to be reduced, requiring greater shunting of blood away from your liver/kidneys/intestines toward exercising muscle. Skin blood flow also tends to be diminished, thus impairing exercise capacity in the heat.

How long have been keto?

Expected. One of the negative consequences of inadequate carbohydrate intake is a reduction in plasma volume, and hence reduced cardiac filling pressure and hence reduced stroke volume. Your body attempts to compensate by increasing heart rate, but cardiac output still tends to be reduced, requiring greater shunting of blood away from your liver/kidneys/intestines toward exercising muscle. Skin blood flow also tends to be diminished, thus impairing exercise capacity in the heat.

So, the increased heart rate is symptomatic of the body trying to get more from the lower volume blood?

Not to hijack the thread, but is there an overall performance limitation to keto-based diets vs. other approaches? I know that people have said it’s a godsend for losing weight in difficult situations.

Expected. One of the negative consequences of inadequate carbohydrate intake is a reduction in plasma volume, and hence reduced cardiac filling pressure and hence reduced stroke volume. Your body attempts to compensate by increasing heart rate, but cardiac output still tends to be reduced, requiring greater shunting of blood away from your liver/kidneys/intestines toward exercising muscle. Skin blood flow also tends to be diminished, thus impairing exercise capacity in the heat.

So, the increased heart rate is symptomatic of the body trying to get more from the lower volume blood?

Not to hijack the thread, but is there an overall performance limitation to keto-based diets vs. other approaches? I know that people have said it’s a godsend for losing weight in difficult situations.

Is there a benefit in the long run by forcing the body to work as effeciently as possible to get the most from the low blood volume? Like do it in the off season and early base periods?

My heart rate was 10-15 bpm higher than normal, I had muscle aches after normal easy paced runs and I felt like I was starting my runs at about 13 miles, i.e. tired from the start.

I was getting dreadful head rushes too, sometimes leg buckling!

I gave up on it, I just don’t think I can train well whilst in Ketosis.

How long have been keto?

2 weeks
.

experimented with keto for 5 weeks. Experienced the same and eventually abandoned as “not for me.”

I am doing high fat low carb for fall/early winter months, and while I am not trying to go fill keto, I definitely notice that if I am too low carb my HR sky rockets. I think I have found that balance where I can stay low carb, but not too low that I have the increased HR. It is amazing the effect a banana in the hours before my workout has on my HR during a workout.

This is NOT a discussion on whether a keto diet is a good or bad idea. It is simply something I told a friend I would try with him for a short time during my off season. With that said, my heart rate seems to be much higher during my workouts. I know there are a lot of other factors such as less volume and still recovering from an ironman, but I was curious if this is normal for someone on a ketogenic diet?

Tried the no/low carb thing for a few weeks way back in the day. Same thing…crazy high heart rate, felt like shit whenever I tried to work out. Abandoned it shortly thereafter.

I did keto about a year ago and, while I didn’t track my heart rate during my workouts, I could only get through about 30 minutes of HIIT because I felt like I was going to pass out (as opposed to 60 minutes on non-keto). I did find that if I felt like crap, a simple electrolyte drink would pick me right up.

How long have been keto?

2 weeks

Most of the literature says that 2 weeks is not long enough for you to adapt. More like 4-6 weeks.

My personal experience was the same as yours. For 4 weeks I had a higher HR, then it was like a switch turned on. I felt great. It never happened for my wife.

is there an overall performance limitation to keto-based diets vs. other approaches?

In a word, yes, especially during shorter-duration, higher-intensity exercise.

Is there a benefit in the long run by forcing the body to work as effeciently as possible to get the most from the low blood volume? Like do it in the off season and early base periods?

No evidence for such, and if anything, you would expect that reduced blood volume/filling pressures would diminish, not enhance, the cardiac adaptations to training.

Dr. Coggan has already given you the answer. My individual results are as follows: on easy runs my pace has decreased from 10:00 min/mile to 11:00 min/mile @ 140 HR. For hill intervals on the bike, on a particular 4.5% grade, my speed has declined from >14mph to <12mph, at 5 bpm higher heart rate. Endurance and heat tolerance have also declined. In the heat, I basically bonk after 1.5 hours at an easy to moderate pace on the bike. I have been on LCHF diet for about six months since my wife went on LCHF to lose weight. BTW, unless you are actively monitoring and controlling for ketones, your diet is probably better styled “LCHF” than “ketogenic.”