Fasting, the second post.
A health and nutrition post.
Blog time : as i start to work on this post it’s a very damp and cold day in late December, in fact it’s the day after the winter solstice (my partner’s birthday) and as far as i’m concerned already next year. This post won’t appear in the schedule until late February or even early March because i do the main work of writing several weeks ahead and that allows me to lay down the main ideas and then slowly tidy it up over a few weeks. In real time as opposed to blog time iv’e most likely now done a much longer fast to start the official new year with, in fact i’m most likely to have done that while most people are stuffing themselves with the Christmas turkey !. I for one don’t ‘do’ Christmas and certainly not in turkey on the plate…..this year our Christmas dinner will be slow cooked lamb shanks in a rich red wine stock after my partner has got some sleep after a run of night shifts.
Back to blog time though….It’s a damp, cold and grey morning in late December and as i start this post it is now 14 hours since i last ate so in my terms i’m just moving into a fasted state : as it is i feel a bit cold, got a mild headache this time and i just noticed the slight metallic taste tang that i get and which i associate with the onset of ketosis. Yesterday we both ate a bit rich and high sugar because we went out for a birthday brunch, then did coffee and cake later on and had a stonking sugar hit later on with a slice of M&S tarte au citron….the full fat and high sugar version too !. Because of that i think i’m having a slightly rougher than normal induction of fasting today : as i say, slight headache and feeling a bit cold although not specifically hungry as that phase seems to pass naturally when i don’t have a conventional breakfast.
Fasting, onset and timing.
Up until December i always started my fast in the evening after my main meal of the day , that then is a fairly normal eating and sleeping pattern in which my physiological processes are well understood ; blood sugar and insulin both drop to baseline, glucagon and cortisol both rise, blood glucose is normally maintained from stored glycogen etc etc. By not eating in the morning i gradually go into ketosis by late morning with or without any noticeable side effects….i think i notice more discomfort during this stage when i have had more carbohydrates in that evening meal or as a snack afterwards. The other variation is what i do about exercise on the first morning, if i do a hard exercise session in the morning my impression is that become more noticeably ketotic. Today, as i write i haven’t done any exercise yet but i’ll be heading out on the trail in a while.
In my most recent experiments iv’e reversed the pattern by having an early ‘breakfast’ and then stop eating at that point especially if i have a physically harder day ahead. It’s purely subjective of course but this seems to feel better for me as i then go through the main period of discomfort during the first night, which i then don’t notice as much, and so by the morning of day 1 i’m already 24 hours into a fasted state. If i break my fast at that stage then iv’e done a 24 hour fast and i might follow that with a fairly normal 2MAD (2 meal day) or more often break the fast in the evening of day 1 which gives me around about a 32 hour fast….that seems to be in the time frame of having useful physiological fasting effects (autophagy/repair and time in fat oxidation) although i prefer if i can to fast until the next morning and thus extend the fast to 48 hours. That might be the sweet spot and best method for me so far as it seems to come with the least amount of discomfort.
I’m beginning to think though, from experience, that it does make a qualitative difference in ‘feel’ how i and when i start a fast and how the final pre-fast meal affects the feel of the fast. What i think i notice is that i get more discomfort if i go into a fasted state from a high sugar state than i do say after a much lower carb content meal. The fast after carbs feel is much more like the initial induction of ketosis that i experienced right at the start of this whole experiment last year and i note that some of the diet doctors suggest that this might be a sugar withdrawl phase just like the similar withdrawl from any addictive substance. My new practice is to be a bit more disciplined with what i eat before and after a fast, if i have a low carb/keto style of meal before fasting i notice that the experience of fasting feels ‘smoother’ somehow and when iv’e done that i feel less hungry and more likely to extend my fast beyond day 1. This might come down to some simple physiology of not having a cortisol/stress response to a high carb meal just before stopping eating entirely for a while and the opposite side is that following a ‘keto’ meal i should be much nearer to baseline for blood glucose and insulin and higher on the satiety hormones.
Fasted, now what ?
A few hours later…..iv’e been out for a soggy walk so that’s some exercise at least although my back is a bit tweaky so i’m not going to any calisthenic work or free weights training today. My headache has cleared which might have been as a result of mild dehydration and perhaps mild salt depletion so iv’e had a couple of mugs of bovril (beef stock) during the day and that’s quite salty. It does seem odd to me to think about adding salt to my diet and having salt/electrolytes during a fast but the physiology does seem sound so i’ll go with that.
The big questions about fasting seem to be about how often and for how long we should fast if we are going down that route. A simple answer is ‘we just don’t know’ because at this stage we don’t have much evidence or clinical trials long enough to demonstrate what the effects are over the long term although what evidence there is from experimental models does suggest that health longevity is increased by fasting. The second major question i had about fasting is ‘what are the risks’ or in other words what is the harm i might be doing by taking regular fasts of moderate duration , and there the answer seems to be a big fat none !.
Having read around the subject a lot i found that i had to first write out the stages of physiological and biochemical events that happen at the various stages of fasting…and then from there decide which stage of the physiology i need to be at to match my goals. In my case i want to reduce my overall disease risks , particularly the diseases that usually appear at my stage in life (60’s) and i want to reduce my visceral fat as far as i can but while holding on to as much muscle mass as i can. For me that seems to point towards a weekly fast of 30-40 hours as it’s then that we should get all of the early fasted benefits plus some autophagy and within that 40 hours should have 24 hours of fat oxidation.
As yet i’m still undecided what the best approach to exercise is during a fast, i tend to walk every day regardless and i don’t notice any difference now between a fasted and non fasted day although i did have one strange experience with feeling very weak and wobbly on an accidental high carb day : i must talk about that one some time as i think it was caused by a rapidly dropping blood glucose. I have done hard free weights sessions and calisthenics in a fasted state and i found it very hard to tell the difference except that i might be weaker on high volume and high intensity work.
In the next posts in this series i want to take a look at the religious and cultural aspects of fasting and then go on to looking at fasting’s dark side….when fasting becomes deliberate or accidental starvation. I should also be able to talk about my own experience with doing a longer fast as by the time i start to work on the follow-up post i should have completed my first long fast ; i’m planning a 5 day fast to start the next stage of my own reset with at the start of the official new year.
Time for a spring walk i think.