No, it is not a side effect of doing 5:2 but I have a couple of suggestions:

If you can’t feel your heart pounding like a bass drum, about explode out of your chest (probably accompanied by chest pains & dizziness) then, a HR of 233 on a 39 yo – whose max HR is 184 – (not to mention the “athletic” resting HR on an unconditioned person) indicates one of 2 things to me:

1. Your HRM is either on the fritz or the watch or the strap (or both) need new batteries (this is the most likely reason).

And if changing the batteries fails, or you buy a new HRM, and get the same readings then:

2. Stop all exercise & call an ambulance immediately because a resting HR of 47-51 is seen in either athletes or very conditioned, fit people (I’m 53, very close to ideal weight & fit and mine is 51-57) or people suffering brachycardia – something that should be checked out by a doctor. As for the high HR, this is indicative of someone who has restricted arteries and is in danger of having a heart attack.

However, as you have normal BP then my money is on your HRM. I use them all the time too and I know from experience that, when they start giving unreasonable & unexplainable “weird” readings then its time to get a new one.

All the best (& don’t die 😀 )

Hi sly_chickee,
I am interested in the results of your ecg. What happened?
I was investigated for the same when I had a healthy bmi, many years ago.
I had always had a very low resting pulse, and it had got lower (low 40s) as I became fitter and Ieaner through a 24 mile a day commute to work by bike. (Bmi still well within healthy range). I had had heart palpations (heart thumping at speed approaching 200) lasting a few seconds to a few minutes since my early teens, but these became more and more frequent. As a child I had mentioned the symptoms, but coming from a family of drs and nurses, it was brushed aside as nothing to worry about.
Nothing was found to be wrong, just a naturally occuring, very low bp. As I approach a healthy bmi again, I am feeling signs that these symptoms are starting to reappear.
Now I am approaching 50, I am wondering whether I should get the symptoms checked out again? Your results might help to shed some light…?
Many thanks.

Hi everyone,
I too have noticed a drop in heart rate since fasting. I’ve been using the FD since late January and have dropped 10kg steadily over the period. I’m 50yrs old, now 86kg and have always looked after my health – non smoker, non-drinker. I was exceptionally fit in my youth but since late 30s haven’t really had time to do training specifically, just tried to do a little each day, eg. I’ll always take stairs over a lift and then try and beat the lift to the top. So still competitive.
Anyway, my resting heart rate has always been between 55-60 but since measuring it recently I’m amazed that it’s down to 44-47 most days. Also it tends to rise slowly from the end of one fast period to the next, where it drops back to the lower rate of about 44.
I’m not experiencing any dizziness or other negative effects either. Another positive effect, that I can’t say is a direct effect of fasting but seems too much of a coincidence, is that every year when I go away I train in the hotel pools with the aim of beating my last years record for underwater distance. This year I smashed my personal best of 50m, set when I was 46, with 60m and could have gone a little further but was so pleased I’d broken my record I gave my lungs a break.
Is it possible that you can fast yourself fitter? I have to add, that at that point I’d only lost 4kg and had been fasting for only a couple of months.

Hi Gariloki, in answer to your question: “Is it possible that you can fast yourself fitter?”

Yeah, I’m pretty sure that’s exactly what you do with 5:2. I didn’t change my exercise regimen at all for the first year and a half on 5:2, I did exactly what I had done before and possibly even a little less exercise. I still massively improved my lung function (was able to go easily from breathing 1 in 3 doing the crawl to 1 in 5 and am now easily doing 1 in 7 and thinking about trying for 1 in 9 as a regular, rather than occasional thing) and general fitness. I could climb the hill behind my house noticably easier after just a few weeks on 5:2.

I’m not sure what my heart rate was before 5:2 but apparently it’s now nice and low and my (usually the high end of normal) BP is now ‘perfect’, along with my cholesterol level and my blood sugar level.

I’m pretty damn happy with 5:2, JUST for the health benefits and will do it forever just for those. The MAHOOSIVE weight loss has been a very happy side-effect though 😉

Hi Gariloki, no – I’ve been doing it since the first week of August 2012 (when the documentary aired), so it’s almost 2 years now. I’ve been on rather a plateau for the past 2-3 months, since introducing more exercise into my life, so the weight-loss inspiration has gone but I’m still keeping the fasts up because I like the health benefits and I know that eventually the loss will kick off again (I still have well over 1 stone to go to my ‘ideal weight’ range, although I’ll personally be more than happy at 10 stone).

As you can see I have a way to go before I start planning what to do for maintenence really but I have checked what my ‘end state’ TDEE would be and I try to aim for that as a maximum on my non-fastdays to prepare me for the level of intake I SHOULD eat longterm. When I get to maintenance I will either go to 6:1 or I will stick with 5:2 and just allow myself a little extra leeway on fastdays or non-fastdays or both. I think it will be trial and error to find what works for each of us longterm.

Hiya – I shouldn’t worry, they’re not known for their draconian treatment of those who digress slightly.

It’s actually the fasting period that delivers most of the health benefits I think (except the actual weight loss – which you can still achieve even if you spread your eating throughout the ‘fasting’ day), so as long as your maintenance model involves (probably at least) 1 period of 16+ hours of genuinely not eating/drinking anything with a calorie in it per week, then you’ll probably be fine. I think I’ll probably do 2 or more of those myself, I’ve got used to missing breakfast on non-fastdays too now, so I should be good.

Hi Gariloki, Yes it all counts. The ‘genuine’ fasting period is what is supposed to affect your IGF-1 levels and produce many of the health benefits (although obviously weight-loss in itself will also provide many of those on its own).

There are lots of different suggestions as to what period is best for the IGF-1 effect but I always play it safe and try to go for more than 14 (I have often done anything up to 24 hours actually and I think I need to get back into that). You can totally count your sleeping hours as ‘fasting time’ though, so yeah, just eat dinner a bit earlier the night before if you want to see if you can get any additional health benefits from it.

Incidentally – if you do have any kind of exercise regimen, try to do it in a fasted state (empty stomach), as that helps with fat burning and actually (for me) improves performance.

Thanks Guys, I’ll look into it more. It seems I’ve jumped in without much research but got instant and consistant results so thought I’d knocked it off. Sounds to me like I’m basically just dieting and that alone is bringing its rewards.
I’ll try longer fasting periods and look into the links you’ve sent to me.
Thanks for your help and advice.
G