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Dr Suresh Khirwadkar
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Guide to prolonged fasting? Ep 07

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Guide to prolonged fasting? Ep 07

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Guide to prolonged fasting? Ep 07

Intro

Welcome to the Meat Medic Podcast. I'm your host Dr Suresh Khirwadkar.

I'm a GP a lifestyle physician and I'm a practicing carnivore. I've had great success myself personally and with patients by following a carnivore diet and I want to spread the word about the many benefits of eating meat.

What is it?

welcome to the meek medic podcast I'm your host Dr sarash kawadka I'm a GP and lifestyle physician and I'm a practicing carnivore I've had great success myself and with patience by following a carnivore diet and I want to spread the word about how to achieve Optimal Health through diet nutrition and lifestyle changes in today's episode we are discussing prolonged fasting that is fasting for more than 24 hours now right out of the gates I'm going to Is prolonged fasting dangerous? tell you this can be dangerous and you should speak to your doctor or a doctor experience in prolonged therapeutic fasting before you start there's also some good books and other literature out there by medical doctors who do this kind of work like Dr Jason Fung that you could read that being said why would you want to do prolonged fasting if it's dangerous well it's not inherently dangerous as I said in my previous episode on intermittent fasting the longest fast ever recorded was actually 382 Days by a Scottish man called Angus Barbieri he lost 276 pounds in that time and he was under medical supervision and was consuming vitamins and other supplements to help him now there's no doubt this is an extreme fast and I believe he was fairly closely monitored by doctors during this time although interestingly he wasn't in the hospital he was actually living at home and just went in every few days now I couldn't find much documentation on exactly what happened and whether he suffered any ill effects or side effects but my understanding the is that if he did it was pretty small and it was it was temporary so we're not talking about doing 382 day fasts no more like maybe one to three days now some people go further and do maybe five seven or even 14 day fasts I know some people that have gone a longer you know to do this some have gone I saw someone the other day saying 42 day fast you know regularly that's that's extreme we're not talking about that now myself personally I've done plenty of one to three day fast I've done a few seven day fasts I would also done one 14 day fast now I've had a few patients do seven day fast as well and I've overseen them through this and monitored their electrolytes and blood tests you know a key intervals I also monitored myself through blood tests during my 14 day fast I guess the question is why are blood tests even required well I mentioned that prolonged Electrolytes therapeutic fasting can be dangerous and that's mainly due to electrolyte disturbances if you don't know what electrolytes are their substances chemicals if you will within the body that help to regulate and control bodily functions cellular processes and generally many aspects of our health and if they're out of balance you can quite quickly have a problem symptoms of electrolyte disturbance can be minor or pretty profound and can even result in coma or death so these things are not to be messed with or ignored thankfully though the body is generally extremely good at tightly regulating these electrolytes even under stressful conditions like fasting but things can go wrong the risks increase almost exponentially with the longer you fast for there's many electrolyzing chemicals within our body that are important for all sorts of functions but the five most important perhaps are potassium glucose sodium magnesium and phosphate these are all usually tightly controlled within the body because even minor disturbances can have pretty serious consequences however that's under normal conditions and prolonged fasts the body can start to struggle with these key substances the most obvious one that will be affected is glucose now generally your blood glucose level Glucose will fall when fasting but it's usually maintained by the body somewhat by processes such as glycogenolysis and gluconeogenesis glycogenolysis refers to breaking down of muscle glycogen and liver glycogen into glucose and glucose one phosphate and the latter gluconeogenesis refers to the creation of glucose from non-glucose sources for example protein amino acids or even lactate these processes are regulated quite carefully by your hormones mainly cortisol glucagon and insulin but if your hormones are disordered then your homeostasis as we call it your regulation can be disordered as well as a result now generally glucose should be between around four to six millimoles per liter or around 70 to 100 mils per deciliter in American units some variations will exist but this is the case for most people locally here in Australia normal reference ranges given are around 3.5 to 6 millimoles per liter for most people now for the most part other than extreme readings a high glucose reading is actually not that dangerous in the short term but can be very very damaging in the long term whereas a low glucose is the opposite it's more likely to be dangerous in the short term and less of a concern in the long term the level at which danger can occur does vary between individuals and to my knowledge that mechanism isn't terribly well understood but likely it's due to your hormonal balance and how well your body can control and handle a low blood sugar I've seen patients with type 2 diabetes have severe hypo events around 3.5 millimoles per liter yeah I've seen medically metabolically well patients with fasting glucose is less than three around 2.8 millimoles walking around like there's nothing happening and not even feeling faint at all likely it's because the other processes such as the Ketone body and fatty acid metabolism is functioning much more optimally in these patients so the brain isn't as concerned with low glucose as it's still getting plenty of energy from those Ketone bodies now typically I'm recommending patients try and stay above 3.5 millimoles per liter and you definitely must eat if you're feeling unwell how you then eat depends on how long you've been fasting for and we'll come back to this later but there's a very dangerous condition called refeeding syndrome that you do need to be aware of now just coming back to glucose briefly symptoms of low sugar low blood glucose otherwise known as hypoglycemia include sweating lethargy tiredness fatigue drowsiness dizziness lightheadedness feeling shaky or trembling shaky or tingling lips tingling extremities heart palpitations mood disturbance and confusion Potassium potassium is another key electrolyte at risk in prolonged fasting it's usually very tightly controlled within the body and both high and low potassium is very dangerous low potassium is mainly the concern with prolonged fasting and symptoms include weakness cramps feeling tired confusion constipation diarrhea drowsiness tingling on numbness chest pains irregular heartbeats or more forceful Heartbeats as with all electrolyte disturbances very low potassium is very very serious and extremely dangerous and can very quickly become a medical emergency generally most doctors recommending or overseeing prolonged fasting will be recommending some sort of way of maintaining your potassium levels such as consuming electrolyte tablets or drinks bone broths coconut water or even maybe pickle juice now theoretically most of these will actually break a fast but realistically they're mostly unlikely to impact a great deal yet they could stop the Electoral ad disturbances you get and be very very useful now as we glucose again if you feel any of these symptoms you should break the fast but take care how you do it because again refeeding syndrome is a big concern Magnesium now again as with the other electrolytes magnesium will deplete over time and the longer you fast forward the more it will go down magnesium is very important but is generally less than a cons lesser less of a concern than other electrolytes the body has very good mechanisms for controlling magnesium and whilst it's estimated that around 75 percent of the world's population is actually magnesium deficient the deficiency is minor in most individuals we don't know exactly why the majority of the world is magnesium deficient but it's postulated that it's mainly due to the low nutritional content of food most of the food that we consume fluoride in drinking water may be a contributing factor but that's not been proven symptoms of low magnesium include muscle cramps fatigue tiredness dizziness nausea and vomiting shaking muscle spasms or fasciculations that is minor movements of the muscles at rest loss of appetite and sleepiness magnesium is harder to keep up than during a prolonged fast than the others the body is quite good at regulating its magnesium levels and a prolonged fast is unlikely to cause significant magnesium deficiency if the levels were good to start with but it is possible in particular if you're exercising particularly weight training it's going to put a lot more pressure on your magnesium levels and could reduce them significantly it's therefore sensible to consider taking a magnesium supplement during a prolonged fast of more than a few days now some take powders some take tablets bearing in mind both of these will probably break the fast so not ideal you probably won't get any magnesium in bone broths so I typically recommend topical magnesium either in Epsom salts or flakes in the bath creams or maybe spray oils spray oils don't give a lot of magnesium though phosphate Phosphate is probably simultaneously the least and the most concerning electrolyte ah I know that sounds odd let me explain phosphate levels for most people are generally quite good because they're present in a lot of food both meat vegetables bread Etc phosphate levels in most people are generally good although some people can have low levels to start with so it's sensible to get your levels checked prior to doing a prolonged fast to sure to make sure that you are adequately replete that means you've got enough before starting the fast phosphate levels will drop with fasting and the longer you fast for the more it will drop symptoms of low phosphate include muscle pain bone pain muscular weakness altered conscious state confusion drowsiness dizziness numbness reduced reflexes and in extreme cases seizures coma and death thankfully this is rare and phosphate is actually quite easy to replenish during a fast by using bone broth hence why it's actually not that much of a concern most commercially available brain broths will have significant levels of phosphate in so consuming these during prolonged fast is likely to keep your phosphate levels very high in fact when I lasted my 14 day fast my phosphate levels actually went up over the course of the fast because I was drinking the bone broths now I'm sure homemade brain rots are fine as well the main concern for phosphate levels is Refeeding Syndrome something called refeeding syndrome and this can affect all electrolytes as I said earlier now refeeding syndrome is a condition in which the body shifts fluid and your electrolytes into cells from the bloodstream most electrolyte disturbances occur when levels in the blood drop not levels in the body as a whole and in refeeding syndrome the levels will drop far more significantly and low phosphate is usually the biggest problem and is usually the Hallmark of refeeding syndrome thankfully it's very rare in the general population and is really only seen in people who are very very malnourished but it does increase with prolonged fasts and the longer you fast for the greater the risk generally fast of up to three days are very low risk for refeeding syndrome fasting three to five days slightly higher risk five to seven the risk is starting to go up and seven days or more the risk can be significantly increased now this is mainly due to the action of insulin the longer you fast for the lower your electrolytes will go but also the lower your insulin will go and the lower your insulin resistance will go now this is generally the idea of prolonged fasting but in refeeding syndrome this is very very dangerous this is because when your insulin resistance goes down insulin Works more effectively which is kind of the point when you're insulin resistance drops your insulin sensitivity also increases that is again your instant will work more effectively which again is kind of the point but we've got now almost really a double effect and a big spike of insulin say from a high carbohydrate meal can have an enormous insulin effect on the body with this double whammy effect this can force the shift of key electrolytes like phosphate potassium magnesium and of course glucose out of the blood and into tissues in the body thereby significantly reducing the concentration in the blood if your levels are already low because you've been fasting for a you know say seven days or 14 days and then they're suddenly dramatically lowered even more it can put you at very real risk of refeeding syndrome which is very very dangerous it's a medical emergency and it can result in severe disability harm and death sudden changes in glucose status could also shift sodium and other key electrolytes so this is the reason why we really want to optimize our electrolytes before the fast and why you should be mindful of what you eat when you break the fast now I think I mentioned in the previous Ending a fast episode on intermittent fasting the breakfast isn't the most important meal of the day but break fast is the most important meal of the day now this is because traditionally we weren't eating three four meals a day maybe once every few days this is what I'm talking about with refeeding syndrome you really should eat a small very low carbohydrate meal ideally even a zero carb meal with just some small amount of protein when you're breaking a long fast you really don't want a big spike of insulin and eating a high carb meal will Spike insulin enormously eating a small protein meal will cause a very small insulin Spike once your insulin has been triggered the sensitivity reduces significantly and you're then at much lower risk of refeeding syndrome and can eat a slightly larger meal a few hours later a few hours later and so on and so forth it's still recommended to eat smaller low-carb meals until you electrolytes are back within normal ranges though now I've got a link in the description to a paper on refeeding syndrome which explains it quite well so you can actually go and read it more on it if you want it's hard to give a universal guide to prolonged fasting as it very much Guide to fasting and SGLT2 inhibitors depends on how long you want to fast for what your medical conditions are what medications you take your previous experiences with fasting and your electrolyte levels before starting the fast as a general guide I would recommend you discuss it first with your doctor as you may require some medical supervision particularly depending on the medications I mentioned before in the last episode about sglt2 Inhibitors with intermittent fasting you really need to be very very careful if you have type 2 diabetes doing a prolonged fasting on these kinds of medications there is a significant and very serious risk of a condition called euglycemic ketoacidosis or eka it's also recommended really that you should get your electrolyte levels checked before starting to make sure that they're optimized once optimized generally I would repeat the blood test every two to three days to make sure they aren't dropping too quickly at the end and then two to three days after the end of the fast depending on the levels then there may need to be subsequent testing if the levels drop too much I will advise my patients to stop the far sooner and safely re-feed and give them guidance on what to do and then do follow-up testing now this might sound unnecessary but remember those electrolyte disturbances are potentially deadly and I really can't overstate this now some people out there are going to say oh well yeah I do it all the time and it's fine great but leave for you but you're not every single person and there's others listening or watching this podcast who might actually have serious issues with this so it's better to be safe than sorry others out there might think oh he just wants the money for consults for these things well actually no I don't because when I see patients and set them up I just give them four or five blood tests to go and get them every few days I don't charge them for that so anyway let's assume now that you've safely done a prolonged fast and you've recovered What to do after a fast? great fantastic now what well you know one would assume if you go back to the way you were eating before the problems are going to come back you had those issues before I'm assuming because otherwise why would you want to do prolong fast because of the way you were eating so if you go back to doing that those issues are going to come pretty much straight back prolonged fasting isn't a magical solution it's not going to give you a Teflon shield to protect you from further metabolic damage if you go back to old habits you'll get old issues coming straight back you need to make long-term changes for your metabolic health there's no quick fixes a question I often get asked is how often can I do prolonged fasting now whilst intermittent fasting is generally safe to do forever I wouldn't recommend regular prolonged fasting as as such most doctors doing this kind of work wouldn't recommend more frequently than maybe every few months to allow the body to recover electrolytes and hormones the balance and normalize more frequent than this could potentially put you at greater risk it's also just unlikely to be necessary unlikely to be beneficial and it is definitely going to give you diminishing returns on your fasting actually that's a good point diminishing returns so what that means is the longer in this context for fasting the longer you do it for the less the benefit is Diminishing returns? there's definitely diminishing returns when it comes to prolonged therapeutic fasting and this is probably due to the hormonal changes now if all you're interested in is the number on the scales then yes you're going to see linear benefits with the duration of the fast because well you're not eating but if you want to be metabolically healthy then you're likely to see less benefits the longer you fast Beyond a certain point now experts in this field disagree at what point the maximum benefit really is but it's likely to be somewhere at or below seven days now I've personally done 14 day fast before and honestly I saw absolutely no benefits Beyond seven days now this is probably because by around three days your insulin level is likely to be pretty much next to nothing in fact mine's then after day three drops to one which is barely detectable I mean it's almost like I'm not even alive I was clearly no longer your insulin is low for the more the insulin resistance will drop but you don't need it to be won forever as long as you don't return to a high carb diet the insulin resistance levels will continue to fall after the fast Growth Hormone growth hormone changes can continue increasing and we do know at what point they're going to be at their maximum sorry we don't know at what point they're going to be at their maximum but there is data to suggest that maybe 40 days however the number of 40 days is probably not much higher than seven days if you look at the data and a 40-day fast well that's that's significantly risky very dangerous for refeeding syndrome a day three growth hormones already 300 higher than Baseline typically and 40 days it's around 1250 percent however this isn't going to maintain forever growth hormone will drop pretty much immediately when you start eating particularly if it's carbohydrates protein and fat don't affect growth hormone that much and in fact protein can increase growth hormone indeed but it's not going to keep the levels at 1250 percent it will drop when you eat so for those reasons I typically don't recommend more than seven day fast an advice advise my patients that Beyond three days really the benefits are actually quite low and the risks do go up I believe in most people in the field believe when you're doing a seven day fast or longer that you also require medical supervision with blood tests and so forth but realistically doing a three-day fast is relatively low risk other than if you have really serious health conditions or certain medications so for people doing three day fast generally for myself if I know them the patient well I know their medical history Etc I often don't even need to monitor them at all they just they just go and do it so I believe the benefits of a long fast really outweighed by the by the downsides and I would probably stick to three days so we've discussed the benefits of a prolonged Fast and The Dangers another fart line on how to do it but what's a prolonged fast actually like what's the experience like What's it like to actually do a long fast? are you just going to be insanely hungry the whole time well actually no you won't not likely anyway depending on your metabolic Health to start with of course but most people are not actually particularly hungry Beyond around 24 hours the hardest part I find personally is around maybe 18 hours then it gets easier this is actually science and it's because of our hormonal changes as you fast your body will produce gorillin the hunger hormone this is to stimulate you to eat however this isn't a constant production it comes in pulses and generally by around 36 hours is actually pretty much next to nothing if you can kind of push through your hunger will actually go down as corellin levels fall at around 36 hours very little to no gorillin is actually produced that's one and a half days the other effect is as the insulin levels are falling a hormone called leptin can start to become unblocked now I mentioned this before in my previous episode on intermittent fasting but leptonas leptin rather sorry is effectively your your fuel gauge you know on your car your fast doors or your gas tank so leptin's basically saying it's okay calm down I've got enough storage you don't need to eat right now don't panic you're not dying insulin blocks the activity of leptin so as insulin levels 4 lectin actively activity rather effectively increases so on one hand we have less hunger signals being produced and on the other hand we have increasing signals saying we already have enough energy storage on board so we need to eat less and this is why you actually don't feel that hungry on prolonged fasts assuming you are actually fasting and not just not eating fasting will generally lower cortisol as well which can also further reduce your drive to eat and increased growth hormone further reduces gorellin generally Beyond three days you'll actually feel maybe you know mostly little to no hunger another question I often get asked is well when I feel dizzy or lightheaded again surprisingly no it's unlikely to happen because whilst your blood sugar may be a bit on the low side it's actually likely to be much much more stable your leptin levels will be higher and your insulin a lot lower allowing your body access to your fat stores for fat metabolism to provide Ketone bodies for fuel this is a slightly simplistic view of what happens but somewhat accurate the original levels will fall allowing more ketosis as we said now you may at times feel slightly lightheaded yes but it's temporary and short term however if you do feel unwell you should break the fast as we've discussed previously Muscles on a fast now one of the more common questions I think I get asked is well where my muscles just well waste away well no this is actually a common myth that your muscles will just waste away if you don't eat it's actually based on very little to no evidence and there's actually plenty of evidence to the contrary we already discussed the rising growth hormone around 300 at three days and at seven days will be much higher now if you've ever done a prolonged fast you'll actually be able to feel this effect just ask anyone who's done one before they'll tell you almost certainly they actually got stronger during the fast if your muscles were simply wasting away this wouldn't be the case when I lasted my my last seven day fast my strength dramatically increased I could lift my wife up like she was just a piece of paper now she's not particularly heavy but I'm not super strong I could also carry one of my kids on each arm at the same time like they were just nothing didn't phase me at all my weight lifting went up all my weight went up but I certainly did not feel or looked like my muscles were wasting away I'm a taxi body scan afterwards which confirmed my muscles hadn't gone down at all in fact they'd gone up actually just a quick note on dexa body scans you should compare like for like so kind of true fasting versus true fasting or eating versus eating or the results will be skewed muscle glycogen will deplete during a fast and will make your muscles look less dense and actually fool with a scanner he'll say they're fat when they actually aren't anyway back to fasting Brain on a fast so what other changes might you see with fasting beyond the obvious bit of hunger and so on and of course we've discussed muscles already what about brain function again ask anyone that's ever done a fast chances are they felt amazing true mental clarity most people report their reflexes their cognition their brain function is just kind of just on fire in in a good way they're just they're just on point quick to respond cognitively agile able to recall memories just in intricate detail that they just never really could before I remember when I did my first fast my first seven day fast I was absolutely blown away by this my memory was kind of like I'm not moving like a 4K like an 8K 16k screen in front of my face just you know full clarity I could recall words from my medical textbooks that I hadn't read in over a decade like I could just see the pages in front of me it was really bizarre all of my senses became heightened my my vision improved I got less sensitive to sunlight my hearing was just pin drop Sharp my cognition and responses were just were just reflex without any effort my wife was actually really stunned when I actually well answered a question that she asked me um and not just the fact I actually heard her and answered but I actually answered the question correctly now my memory isn't fantastic for small details especially dates I kind of get a lot of things wrong and she always corrects me so actually it was a bit unusual that I would just fire off this answer without even thinking getting it correct especially the fact that she was about 10 meters away and I was boiling the kettle and I could barely hear her yeah I just answered without even I thought let's think about this from a nature or Fasting in nature an evolutionary perspective and it might help to explain maybe why this is the case so predators in the wild and of course humans we are predators by Design we should be no exception now predators don't eat 24 7. in nature they didn't go to McDonald's you know the lion doesn't go to KFC when they're hungry so they go hunt they run they expand energy they have to generally catch their prey scavengers are different of course most big predators will eat every few days maybe sometimes I can even go weeks between meals if they can't catch anything now if they got weaker and frailer the longer they didn't eat well I mean basically by the time they they try and catch something they're not going to be able to they don't get weak and frail their muscles Don't Fall to Pieces their brain doesn't turn to mush if they did they'd never catch anything they'd die in fact often it's actually the opposite if you watch any any nature program you know their energy levels actually seem to go up their brain and reflexes get more acute and they become better Hunters after all at some point I mean if you can't catch something you're gonna die so it makes no biological logical sense for your brain and body to just disintegrate and turn to mush if you don't eat for a few hours even a few days if anything it makes sense that it would improve to make sure you can actually catch your prey this would be an evolutionary advantage surely then repeated fasting should be a really good thing then well there's not really any evidence to actually support that doesn't mean it wouldn't be but I think you probably get very limited benefit from frequent fasts again you know lions tigers Etc they're not fasting for months on end every few months now this is a random thing yeah maybe every few months it could be a good idea to fast maybe reset our metabolic Health Etc Conclusion but that's mostly just unproven and pretty much just conjecture on my part so should you do prolonged fasts and what's the ideal time frame well there's no real evidence to say the people that fast have better health overall there's lots of evidence that fasting and fasting mimicking diets the fmd can be beneficial for health I personally think that most people should do prolonged fast occasionally and whilst there's little evidence on what the best time or duration for a fast is I usually recommend about three days it's sufficient to see the maximum return on investment with minimal risk after three days there's definitely diminishing returns and increased risks but who shouldn't do prolonged fasts well like with anything generally pregnant or lactating women breastfeeding women shouldn't do prolonged fast children should not do prolonged fasts babies definitely do not fast now again there's no evidence to say it's harmful but there's also no evidence to say it's helpful in these individuals and they would be a higher risk of harm people with certain medical conditions as I said should also be wary about prolonged fasting particularly those with diabetes especially type 1 definitely type 2 if you're taking sglt2s or you have glucose issues those with kidney problems liver problems history of gout because fasting can trigger gout and history of kidney stones anybody wanting to do a fast longer than 24 hours I believe should seek some medical guidance even though it's generally safe it's good to have these discussions with people just to make sure that they are being safe that there's no issues thank you for tuning in to this episode of the meet medic podcast subscribe for more episodes and if you want to support this podcast please see the links in the description

Conclusion

Intermittent fasting can be incredibly potent, and potentially has multiple health benefits. It's proven to be beneficial in fat loss and diabetes and anecdotally helpful in many other conditions. It's easy to do, requires no special training, no supplements or pills, and can be done by almost anyone. If you're pregnant breastfeeding or a child it's not routinely recommended so, if you do fall into these categories then you should speak to your doctor about the risks and benefits of intermittent fasting.

If you are looking for a guide on how to start a carnivore diet, click here

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