My GP is concerned about my blood pressure as it was an average of 137/80 and wanted my to take medication to lower it.
So I have been monitoring it and discovered that when I am between 24 and 36 hours fasted my blood pressure is high. Shorter times or longer times is fine. And I also seem to be very sensitive to salt when fasting. One reading was 202/103 - so I broke the fast and it dropped to a more reasonable level.
I believe this is what made my average high in the figure the doctor was concerned about (but I wasn’t monitoring the fasting and salt at the time). As my average now is about 125/80 since I stopped all electrolytes when fasting. I don’t fast for more than 72 hours and have followed a ketogenic diet for 10 years next month. But the 24 to 36 hours fasted figures are still high just not crazy high.
I was told that my body is under stress when fasting and so that is why the blood pressure raises.
Does anyone know if this is normal?
And is there anything I can do to lower the blood pressure while fasting?
I do not want to stop fasting as it is the only thing that reduces my insulin resistant.
Raised blood pressure when fasting
Correct, stress out your body, and things like Blood pressure, resting heart rate, stress hormones like cortisol are all going to push back. Your body doesn’t like when you don’t eat!
Listen to your body, your body clearly REALLY doesn’t like it! So don’t do it. Transient rises is one thing, going from 137/808 to 202/103 is WAY beyond an acceptable rise.
Eating correctly over time does that, if you’ve been keto 10yrs and you’ve been doing it even half right, you shouldn’t still be insulin resistant. Are you sedentary? Do you exercise or hopefully do resistance training? Because those put a huge dent in insulin resistance very quickly.
I discovered it was the electrolytes plus the fasting that made it go that high. Once I stopped the electrolytes it only goes to a max of about 150/85.
What is an acceptable rise?
And does anyone else monitor their blood pressure while fasting? Am I abnormal?
All one of the doctors i saw was worried about was the average, not the peaks.
I have never done that (measure blood pressure while fasting), but I tried to fast 7 days, and quit at 5.5 because I was getting dizzy when standing. Because insulin is going down, blood pressure should go down over time. But maybe there’s a short term rise?
Are you still taking medication while fasting?
I’m with you about the “insulin resistance”. According to my data, my fasting insulin is still mostly “high”, over the point at which many would call me insulin resistant, but the only way I can get it down is to fast. If I eat, it remains higher, at least to the extent I can tell.
It seems to me if it is making your blood pressure go up, even to 150, your body does not like fasting. Maybe listen to your body. If you are not ready to give up, maybe try a fat fast and see how your BP reacts to that. That might not be as stressful on you body. If your BP still goes up, I would say fasting is not for you.
I (61) can’t fast like I used to, 24 hours max. My husband (72) can’t get into ketosis anymore, the side effects were frightening (dizziness, severe palpitations, he felt ghastly and his breath smelled dreadfully of garlic, which actually concerned me the most).
This is why I can’t fast for more than 3 days. By 72 hours my blood pressure falls. Last time I tried it was 88/62 and I had to sit up for a while before trying to stand up.
I am not on medication, even though the doctor prescribed it.
Whoa, that’s low. That’s definitely time to quit the fast.
If you can’t do a true “fast”, there are other options, like a fat “fast” or even one of the new “sardine” fasts. To me, the fat one likely would have the least insulin response, though the sardine one probably wouldn’t be that much worse in terms of insulin response.
I googled what a fat fast was and it doesn’t seem very different to my normal diet.
I also have an appointment with yet another doctor from my local practice (let’s hope this one actually listens and understands what I’m saying).
In the meantime I’m trying the sardines (at least it is cheap!) But I’m not sure I can manage this for very long - I would rather just not eat.
First, I want to say that it’s impressive you’ve been able to maintain a ketogenic lifestyle for so many years and complete fasts of up to 72 hours. That takes a great deal of consistency, self-awareness, and psychological resilience.
That said, I am concerned about the blood pressure readings you’re seeing—especially the 202/103 measurement. Even though it came down after you broke your fast, that’s not something I’d be comfortable dismissing as a normal response to fasting.
The fact that you’ve carefully tracked your fasting windows, blood pressure, and electrolyte intake is incredibly helpful, and you’ve identified a pattern that’s worth discussing further with your GP. While fasting can act as a physiological stressor for some people, it’s important to understand why your blood pressure is spiking rather than assuming it’s simply part of the fasting process.
Since fasting appears to be helping your insulin resistance, I wouldn’t necessarily jump to abandoning it. Instead, I’d encourage you to work with your healthcare provider to see if there’s a way to preserve those metabolic benefits while also keeping your blood pressure in a safe range.
Keep taking such a thoughtful and proactive approach to your health- you’re doing a great job listening to your body, and I hope you continue making steady progress while staying safe.