Keto: Body Temp and Heart Rate Variability (HRV)

#1

Help me process some personal experiment results. A little background first. I also come in peace. Im not here to challenge keto; just trying to get some answers.

I am a 41 year old male. 5’9, 160 lbs. I have been doing a cyclical keto diet for about 7 months. I was full keto for about 3-4 weeks to get adapted then started having carb days on Saturdays. I am NOT trying to lose weight. I wanted to try keto for general health and the concept / science appeals to me. I think it’s generally the best diet for health and longevity. After I was fat adapted, I could eat carbs on Saturday and by Sunday afternoon, I could be peeing ketones again so I was getting back into ketosis relatively quickly.

Over the past 7 months, my body temperature has decreased. It’s not unusual for an early am temp to be around 95.9 and to climb up to upper 97 or low 98 by afternoon. Now, we know that a ketogenic diet lowers T3 and may increase reverse T3. I’m not sure if this is a negative reaction from keto or a positive. There have been numerous studies that show that a lower metabolic rate leads to longevity. But there are countless medical opinions saying low body temp is cause for concern. So, I am concerned about the low body temp. Am I wrecking my thyroid? I’ve never had thyroid issues in the past.

Next, I have an Apple Watch and keep track of my heart rate variability. I didn’t have a pre-keto baseline but since keto, my HRV averages around 45. That always seemed a bit low to me but I don’t know.

I decided to experiment a bit over the past week and add in some carbs daily. A little oatmeal at breakfast, fruit, and some potatoes. Not a lot, maybe 100-150g per day. Enough to stop ketosis though. After about a week, my morning temp is about 97.1 and gets up to about 98.2 in the afternoon. My HRV is averaging about 80 with this am’s reading at 116. That is a substantial increase.

So, what gives? Overall, I like ketosis. My workouts are going great and I feel ok although I sometimes get minor pains in my right side/back/abdomen. I had them checked out and nothing showed up.

Is the low body temp cause for concern?

Is the lower HRV while in ketosis indicative of stress on my body?

(Tom Seest) #2

I find HRV to be an excellent way of tracking stress in my life, and use it to guide fasts. However, I’m not sure how accurate the Apple Watch is for it (I own one) so I track it with a chest strap ( Polar H10). Once you’re sure the watch is accurate, I’d continue to experiment and see what you find. In my case, my levels of stress are better if I don’t add in carbs but I assume that this is reflective of our individual circumstances.