I’d see a doctor. Most people who do IF don’t have this issue, or at least it isn’t significant enough to notice.
Assuming you have a fitness watch/monitor to track, you should write down your numbers to give to your doctor to see.
I see there are several things here to unpack. First how frequently are you drinking fluids. What are you drinking?
What are your macros? Percentage wise.
How much fasting time are you having between meals?
And yea I would have that checked up as well
You’re not going to get a good answer the way you asked the question. You are missing a lot of specifics that would give everyone context.
What do you consider significant? What is your resting HR before fasting and after? Is your meal time in the morning after you wake up or in the afternoon? Is it in the evening? How much water are you drinking?
If you change your meal time, does the HR change the same amount? Or is it a time-based change?
Are you having coffee with your meal? Or any other stimulant?
I think I was the same. I would use propronol to lower my high heart rate. Now, 5 weeks into IF and low carb, my heart rate feels normal and I haven’t used the beta blocker for a long time.
Not medical advice, just my experience.