Feeling cold at night at the end of a 36 hour fast

OK - just putting a marker down that today is a fasting day (or at least the start of one).
For what it's worth; I'm less sure that I need to fast; my blood glucose was rock solid over night - a flat line around 4mmol/L and my fasting ketones are actually higher than I've ever measured. My visceral fat (as measured by my scales) is under the level that I usually set as a limit.
My overall weight is about 0.5kg over ideal, so I'm not worried about fasting losing weight I cannot "afford" - and I still believe in the wider benefit of fasting - but mainly this is an opportunity to run a fast from a "good" starting point while wearing a CGM; and I cannot resist the temptation to do this as a way of gathering evidence in my ongoing experimentation of my own metabolism.

So - all of that for context: I will do some paddling now, and then later I'll have a walk in the evening - the key thing is whether I have any issues with sleeping tonight.

If I do: and the rest of the numbers bear out why I have any issues with sleeping, I will have to conclude that the benefits of a 36 hour fast no longer outweigh the attendant grief - and be happy that this means that this kind of fasting just isn't necessary any more, and that the kind of 18:6 style of skipping breakfast fasting is optimal.

But - I'll be kind of sad if that is the outcome - I mean, I'll repeat this again; fasting is not for everyone - but I have found it to be the most amazingly effective technique for reversing insulin resistance, and as a "mechanism guy" - there really isn't anything that simply makes more sense to me - regularly emptying your glycogen storage just has to be the most effective and quickest way to beat T2DM (if you can do it) without meds.

So - we'll see; I'll report through the 36 hours, but I could not be starting off in a better state..

So, apologies in advance - I'm likely to go overboard with information over the course of the next 24 hours or so...

But this is the first "morning transition" -


As many will know from my other ramblings, one of my big bugbears is the dawn phenomenon, and that my understanding of "aiming for low insulin" as opposed to "aiming for better blood glucose control" is that over time, you should see an improvement of (therefore a reduction in) the blood glucose raise in the morning that we call the dawn phenomenon. Your body's routine for getting you ready for the day is much more complex than reacting to your breakfast, but with a low background insulin level, you should expect that your blood glucose will just flip from "night-time" to "day-time".

I typically wake up the same time every day. Just before I wake up, my blood glucose starts to rise... my heart rate is noticeably faster as well. After I get to my "day-time" state - everything settles down. Obviously - no food is involved in this at all.

It will be interesting to compare this with tomorrow, because this morning transition can be acheived with stores of glycogen in my liver (glycogenolysis - breaking down of glycogen into glucose) or stored in skeletal muscles, but there should be none of that left tomorrow morning, so any glucose is going to have to be made fresh (gluconeogenesis, the creation of new glucose from anything that the liver can get hold of.. but may include broken down cells and bits of protein that come from the autophagy - literally "self-eating" or cleaning up the trash which my body will be able to do because it's not totally absorbed in dealing with incoming food - or at least that's the idea; at some point your liver will decide that there isn't enough trash around and will start to convert muscle - that's what we are trying to avoid).

Anyway, so far so good.

Ok - getting into the evening now; you can see that the level has remained totally stable all morning.

The rise at lunchtime was entirely driven by paddleboarding - a short sharp session, and now we're into the proper blood-glucose lowering phase. For me, the period of time between lunch and dinner is usually the most difficult (I hesitate to use the word, because it does vary, and it isn't really hard, but there is no pretending that I'm not a little hungry) but usually after the time I would normally have had dinner, everything settles down, and I don't keep feeling more hungry.

As far as the trace goes, you can see that I'm starting to drop below what would be my "normal" for the time of day - that dropping is what drives the sense of hunger, but also drives release of Glucagon (to start producing more glucose and drive insulin lower) and that is why the normal hunger feelings should pass.

I don't get any of what Catherine Shanahan would call "pathologic hunger" because as far as my brain is concerned - it's fine; it has plenty of energy from ketones, so doesn't need to send any signals down to my pituitary to start releasing stress hormones.

However - If I'm honest, I do feel just a little colder than I should, and I'm aware of needing to twitch my feet to keep them warm as I type.

So - what I often like to do during a fast, is have a sauna. My initial idea with this is that a sauna should cause an increase in metabolic rate (and actually help with the "liver draining"). It may well do that, but I now prefer to think of the action of simply heating the body to the point of sweating being more about cleaning up the cells - you are literally causing the reactive oxygen species to become more mobile and to leave the body in the sweat. You need to be fairly hot before that happens - but when people talk about sweating out toxins - there is something to that... Anyway, it will also definitely warm me up, so I can see whether I'm cold after that or whether I'm just needing to get up and move about.

Now fully into the second evening, so the "interesting" bit of this little experiment.
This is where we are as far as the CGM reading goes:

So, had a walk around 5:30 and then the sauna (this is one of these newer sauna blankets, pretty reasonable and very effective) about 7, so I think you can say that the effect of heating in a blanket at least drives up blood glucose a bit - and that was the plan, because now, after ~24hours, my stores of glycogen should be totally empty.

The trace is a more or less straight line from 6 - my current "day-time normal" to about 4 mmol/L where it is now. I suppose I expect it to more or less stay that way till the morning.

I'll have a glass of water now, with ~1gm of salt, crushed very fine, and report in the morning.

So, the overnight results are in; and the simple version is that I had an excellent sleep:

The trace is totally as predicted, bumping along around 4mmol/L all night.

I haven't yet gotten the core temperature measurements from my watch- need to log some steps before it has enough of the day to look at.

On the other hand - I can see that my overall weight is down 1.2kg - and that I can be reasonably sure that this is all fat mass that has been lost - not muscle; indeed, if I consult my scales composition:


You can see that my Muscle mass is stable, and fat mass is down, over the week.

So - this exhaustive reporting is really about me keeping myself honest - I wanted to publically run a 36 hour fast, but predicting what I expect to happen, and log what actually happend - as a way of honestly deciding for myself if this kind of fasting is still a benefit in the round. It takes some effort, it does get in the way, and I need to be motivated to do it, otherwise I would find myself gradually doing less and less.

I'm happy to conclude that my last experience must have been a one-off, and that if I properly prepare, I should not be uncomfortably cold during the night of a fast, though I do need to acknowledge that I felt a "tendency" to coldness - maybe this is another long term thing, where I will become more sensitive to thyroid hormone over time and feel warmer again. Just speculation for now.

What this does show - in some detail - is the value of fasting. It wasn't my intent, and I hate the idea of being evangelical about anything - these things are all personal choices, and what works for one, may not work for another. If I've learned one thing, it's that we are truly all different.

However - you can see from the CGM, that fasting - when you are sufficiently used to doing it (and that is a big point - you can see that there are zero stress impacts - this is overwhelmingly a simple, enjoyable experience for me, it's causing no stress) it significantly pushes down blood glucose - it kind of cannot do anything else, as you use up all of your stored glycogen - and so in the short term, you have to switch to fat burning and using ketones (though surprisingly this morning I'm in "solid" rather than "high" ketosis.

In the longer term, I totally believe (and my average trend chart above shows) that this takes you towards becoming more fat-adapted, where its just easier to flip between burning fat and burning glucose.

That is my long term goal - not necessarily to be in constant high ketosis; but to be able to go between meals without feeling hungry, and to have a flexible metabolism, which should mean healthy mitochondria.

Just a quick update on this - I thought the thing was done, but I think now I should give this follow on...

One of the questions I had over the last six months or so was around the day after a fast - it often seemed that my ketones were higher in the day following a fast, more even than during the fast itself, and I didn't know how to explain that, so kind of ignored it.

So, this over-detailled fast has gone almost to the minute as expected, and I've been able to report before and after, and been able to feel like I'm pretty up with what's going on in my body - again, none of this is designed to be a recommendation for anyone else.

However - this morning (now after a whole day of eating normally, and eating well, I did not go to bed hungry in any way) my blood glucose was again low. Not worryingly low, but lower than "my normal"- fine.. and I waited for my ketone results...

44.

Now, for context, at the end of my fast the level was 12. These are measurements of acetone in the breath, so the units are different, but the level of full ketosis is 5 and the level of ketoacidosis is 40. So - I used up one of my small stock of blood test strips (I use them very rarely to calibrate the breath monitor) - that came out at 3.2 - so; I still have a memory (and notes) of my time as T1, where anything above 3 and you rush to hospital; this is emergency territory.

But - I don't feel in any way bad - minus the growing sense of unease about these results - should I drive to the hospital, try not to stress, or do something else - just not panic...

I finally come to the conclusion that ketoacidocis is very elevated ketones AND very high levels of blood glucose, and my blood glucose is very low. So there is probably nothing to worry about, as long as I can drop ketone levels just a bit - now, what would do that - a little insulin.

So - I had an apple (which was wonderful, I haven't had an apple in months..) and sure enough, blood glucose jumped from about 4 to 7. As soon as I saw that it peaked, I did a blood test (would have to wait 30 minutes after eating to do a breath test) and that showed 3.0 mmol/L - so; panic over. It would seem that my ketones are also peaked, and just back below the level of needing to worry.

Overall - I suppose I have to conclude that fasting is not just about the period of time that you are not eating, and that the effects last for a day or two after resuming eating (which is good) - but that doing a lot of exercise (2 hours of hard paddling is not so different to 2 hours of running, which would get you a chunk of the way around a marathon course, so it's substantial) may be just a little too effective - at least for me, now - in driving down insulin and promoting ketone production.

That's worth knowing, and worth sharing - in some ways it only reinforces my sense of how effective fasting can be as a tool to reverse insulin resistance and promote good long term health - if you can do it (acknowledging that it's not possible for some).

IanBish said:

That's interesting. What scales do you use?

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Withings Body Composition. I've used Withings stuff since long before I was diagnosed - you may or may not be surprised to know that I also have a Withings hybrid watch, blood pressure monitor (the same kind of thing you use at the GP but with extra bluetooth), non-contact thermometer (bought during covid) and a sleep monitor that goes under the mattress. The watch also does sleep, but the information is not so detailed, it just means that if I'm away, I maintain the record, and the watch charge lasts for nearly a month. (watch also does EKG, VO2, temperature, and activity tracking) Huge fan of the products.

The main thing about Withings is that the EKG and blood pressure are all approved medical devices - so you can actually print out a full summary of health markers and share them with your doctor - which I have done a couple of times to hilarious effect; the GP couldn't refuse it when offered, but then had no idea what to do with it...

But the scales are awesome - they even wish me happy birthday!!
Total weight, composition - water, fat, muscle and bone - visceral fat, a measure of vascular health, nerve health and lean mass / BMI.
All of that sounds a bit overwhelming and excessive, but you only need to do the one thing and all of it shows up on the app, so you can spot trends very quickly.

Outlier said:

Very interesting report and thanks for taking the trouble.

As a personal experiment of one, I have found over a long time that I get too hungry to fast beyond 24 hours, and oftener 20. So much as I would like to, and feel it would probably benefit me, I'm one who can't get past the hunger barrier. It just will not let up. I say this so that anyone else who experiences similar results won't feel as if they are the only one. I have never had hunger pangs wear off and these days lack the moral fibre to endure them beyond a certain point. However, if I didn't get hungry, I suspect I wouldn't bother to eat at all, so maybe that's a useful bit of biology. I love food, but life would be so much easier if I didn't ever feel hungry.

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Thanks for the feedback and insight.
My sense is that fasting, more that any other technique, carries quite a lot of baggage, which is odd because pretty much every culture has used it as part of some kind of religious or symbolic ritual. it's unlikely to have survived as such a core part of so many cultures without some inherent benefit.

And, you know, without preaching - I think I can see the medical benefit of getting to a point where you are not hungry between meals - the idea of snacking every couple of hours is the thing that is new, untested and very much driving poor health. But - there are lots of ways to get there that don't involve not eating for more than a day.

And for what it's worth, around 20 hours is the point of peak hunger for me too. I think, for me - I was totally determined in January to get to a point quickly where I could get my GP to agree that I could carry on with no meds, that the only way seemed to be to fast every other day - I agreed with the science, and I was pretty sure I could do it in a safe way. Not eating every other day is pretty extreme, and I can't pretend that the first week or so was tough - but I was fired up - I was going to deal with anything; and the truth is that this extremity meant that after a fortnight (and the evidence that it was clearly working) or so, it started to get easier, and became more a problem of planning not to interfere with social events than an exercise in managing hunger.

AloeSvea said:

So yeah - fasting in a northern-ish winter, as you are doing, perfectly normal to have to keep more rugged up, as others have suggested to you.

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Thanks Aloe - but this is very much the point of intermittent fasting - it is not the same as reducing calories.

With any form of medium-term calorie restriction, your body will adapt by reducing base metabolic rate - by up to 40% - that's really why traditional dieting is so difficult - you have to reduce calorie intake by more than 40% to start to make a difference.

To relate to more traditional Scandinavian practices - the effect is very much like a sauna and plunge pool. In both cases, if you were to stay in them for days - you would die. In short - dare I say intermittent - doses, they are beneficial, because they "surprise" your body systems.

There would be totally no point in going into a "slightly tepid" sauna...

Outlier said:

To clarify for me personally, I have never snacked - I wasn't brought up that way - it's helpful to know that 20 hours is peak hunger for you too -

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Understood - and apologies if there was an implication.
It wasn't my intent, it's more that (and pardon the leap) Dr Catherine Shanahan talks about "pathologic hunger" - and this is, to oversimplify; "hangry" taken to extremes. We think about being "full" - but there is a totally different system that kicks in when your brain feels like it's low on energy. You become irritable and stressed (for example, there is a connection between domestic violence and low calorie diets - nobody talks about that...).

So - one of the aims of any form of eating (whatever the terminology) and not-eating... should be to feel more satisfied, and essentially not have any "craving" for food - because that's almost always not a good thing.

I shudder when I come across these advertising boards in service stations "satisfy your cravings!!!" and shelves of supposedly healthy high-protein bars - but they are closer to drugs - and you cannot get away with advertising drugs in the same way - everyone understands that...

and one product that somehow has made it into my Google feed - 10PM - a brand of snack designed to be eaten late at night - their tagline is something like "late night snacking has never been so good" - It would be like advertising a vodka brand with "when you need that hair of the dog quickly to get your drink on"

Not sure what you mean there - the 24 hour clock is only an attempt by us lowly apes to measure the 24 hour cycle of the earth spinning on its axis...

Ah, I think what you're saying is that non-eating in a strict rotation around the 24 hour clock was something that humans have had to do throughout history.. in which case, yes; I do know what you mean, and totally agree.

The circadian cycle, however, we avoid at our peril - that is very much tied to the earth spinning around it's axis, and you can see for example, that my blood glucose "switched up" into day mode at almost exactly the same time on both days - just less so when there was less stored glycogen.

I'm learning that I'm very much an afternoon person - my energy levels are highest in the afternoon, but another person may be much more full of energy in the morning or evening - or I caught an interview with an author who writes till 4am then sleeps till midday - leaning in to the part of the day that you have most affinity for has to be a good thing, but easier for some than others - like working shifts or travelling.

Melatonin - that kind of does wipe clean every night, and start filling up as soon as we wake up..