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Intermittent Fasting, Cortisol and Blood Sugar


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There’s been a lot of discussion about the benefits of intermittent fasting (IF) in the paleo community lately. Paul Jaminet mentions it’s role in boosting the immune system in his book, The Perfect Health Diet, and IF can also be helpful for those trying to lose weight and tune their metabolism.

From an evolutionary perspective, intermittent fasting was probably the normal state of affairs. There were no grocery stores, restaurants or convenience stores, and food was not nearly as readily available or easy to come by as it is today. Nor were there watches, schedules, lunch breaks or the kind of structure and routine we have in the modern world. This means it’s likely that our paleo ancestors often did go 12-16 hours between meals on a regular basis, and perhaps had full days when they ate lightly or didn’t eat at all.

So, while I agree that IF is part of our heritage, and that it can be helpful in certain situations, I don’t believe it’s an appropriate strategy for everyone.

Why? Because fasting can elevate cortisol levels.

One of cortisol’s effects is that it raises blood sugar. So, in someone with blood sugar regulation issues, fasting can actually make them worse.

I’ve seen this time and time again with my patients. Almost all of my patients have blood sugar imbalances. And it’s usually not as simple as “high blood sugar” or “low blood sugar”. They often have a combination of both (reactive hypoglycemia), or strange blood sugar patterns that, on the surface, don’t make much sense. These folks aren’t eating a Standard American Diet. Most of them are already on a paleo-type or low-carb diet. Yet they still have blood sugar issues.

In these cases, cortisol dysregulation is almost always the culprit. When these patients try intermittent fasting, their blood sugar control gets worse. I will see fasting blood sugar readings in the 90s and even low 100s, in spite of the fact that they are eating a low-carb, paleo-type diet.

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That’s why I don’t recommend intermittent fasting for people with blood sugar regulation problems. Instead, I suggest that they eat every 2-3 hours. This helps to maintain stable blood sugar throughout the day and prevents cortisol and other stress hormones like epinephrine and norepinephrine from getting involved. When my patients that have been fasting and experiencing high blood sugar readings switch to eating this way, their blood sugar numbers almost always normalize.

I don’t think eating every 2-3 hours is “normal” from an evolutionary perspective. But neither is driving in traffic, worrying about your 401k, or staying up until 2:00am on Facebook. The paleo template is there to guide us, but it’s not a set of rules to be followed blindly. This should also be a reminder that there’s no “one size fits all” approach when it comes to healthcare. Successful treatment depends on identifying the underlying mechanisms for each individual and addressing them accordingly.

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  1. Dr. Fung wrote this article that discusses how cortisol and other hormones affect our blood sugar. Although Dr. Fung is a proponent of Intermittent Fasting, I read this article as not agreeing with what Kresser wrote. That is, if your *other* blood sugar hormones are not functioning correctly, you can have blood sugar problems.

    “Just before awakening (around 4am), the body secretes higher levels of Growth Hormone, cortisol, glucagon and adrenalin. Together, these are called the counter-regulatory hormones. That is, they counter the blood sugar lowering effects of insulin, meaning that they raise blood sugars. The nocturnal surge of growth hormone is considered the primary cause of the DP.”


    • Thank you for this link. As a type one, I wasn’t undestanding my high bs while IF. Maybe I can snack on cucumbers or seeds to keep me balanced.

  2. All this conflicting information and flip flopping by these medical and nutritional gurus is so confusing and frustrating. I can see how many people can just want to throw their arms up and say “the hell with it all”. As for me, I’m going with what works for me. I feel and look enormously better eating vlc with intermittent fasting. My fasting bg does at times go up but as Kresser himself said in another article, it’s not a cause for concern when you’re in physiological insulin resistance. I’m a believer in Dr Fung’s program and I’m determined that my genetic predisposition will not have it’s way with me as it has with so many of my family members. And so far, so good. I’ve recently come across a few of these anti fasting/low carb cortisol/adrenaline articles and viewpoints which have made me question the low carb/IF/Keto path I’ve been on. And then I’ve researched it more and have found just as many articles from other experts with the opposite viewpoint. So until I find some real science that says some temporary elevation of my cortisol/adrenaline levels is worse than Diabetes, I’m sticking with IF and Keto.

    • I am on vlc and IF. Occ longer term fast. My sugars fluctuate. But overall they are improved. I am quickly down 17lbs and pressing on.

    • My 2 pennies of thought.
      The key to insulin resistance being kept in check after weight loss and IF is weight training and or HIIT. This is key to reversal.

  3. Was wondering if anyone could explain why I get shaky AFTER eating following intermittent fasting? Doing 16:8 or sometimes 20:4. I feel fine before eating then 20 minutes after eating I get that internal shakiness and heart pounding. I am not eating junk and have been very cautious as to was I first consume after a long fast .
    My last A1c was 5.8 down from 5.9 months before but it is stil to high according to my Dr. I have lost about 10 pounds and trying to lose more to get A1c down.
    Anyone have any idea??

    • Are you drinking enough water? Water keeps the hunger down . If this is happing drink soda water too! It really curbs your thirst , and your hunger. Eat celery, carrots , these are water base , if you like tart fruit , bring rhubarb , I love it eating it after cleaning the skins keeping some water in a lunch bag to keep them moisten. Go on Pintrest check out food to eat on intermittent diets with lots of water substances in them , to keep you strong through your fasting .
      I hope it works ! And I hope I can help you out !

      • This is the adrenaline (norepinephrine) he spoke about in the article. I get a similar feeling at times. I finally had my naturopath discover what it was.

        “Eating at 2-3 hour intervals helps to maintain stable blood sugar throughout the day and prevents cortisol and other stress hormones like epinephrine and norepinephrine from getting involved.”

    • Potentially a food intolerance? Gluten makes my heart pound…so I stay away from it now. So does sugar…even dried fruit. So I stay away from that. Food logging helps figure these things out so that might be a good thing to try.

  4. For three weeks I have been intermittent fasting eating within five hours. During this time my blood pressure has been consistently higher than usual, especially in the evenings. My diet has been varied and not necessarily Paleo or low-carb. Chris’ article about cortisol makes sense to me. Maybe I will increase to eating within 8 hours and try to balance my meals better or even try lower carb (I love lima beans and sweet potatoes.) but not zero carb, ugh! I think my body is feeling stressed by not eating 16 or more hours every day. I know I am still a sugar burner and would have to be really strict to start burning fat but I don’t want to take blood pressure meds.

  5. Too bad author doesnt say that usually low carb diets result in increases cortisol.
    Also its very funny how Kriss in another article explains why higher BG on keto is ok beacause its “physiological” and even 110 foesnt hurt but in IF its suddenly dangerous and bad.

    So maybe your patients are insulin resistant cause of fat excess and hypercortisolic because of lack of carbs?

    • Find Dr Jason Fung’s blog. There you can find the explanations to why your assumptions are ill-founded. High Fat diet does not cure insulin resistance but it prevents blood sugar from rising high taking none or less insulin. Intermittent fasting, however, will cure insulin resistance, best when done a few days in a row, weekly. After that, fasting glucose becomes normal again once the liver fat is consumed through the fasts. Then BG remains normal, with or without carbs.

      • Perhaps you (and everyone else lambasting Chris) should follow your own advice and go read Dr. Fung’s latest blog post.
        “A few other notes about the hormonal changes of fasting. Notice that cortisol does go up during fasting. Yes, fasting is a stress to the body and cortisol acts as general activator as well as trying to move glucose out of storage and into the blood. So, if too much cortisol is your problem, then fasting may not be right for you.”

        There is no miracle pull or treatment that is right for everyone. IF is fantastic for many people (I am 3 days into a 7 day water fast as I write this) but I am healthy, have no hormonal dysregulation issues and I check my cbg and ketone levels every morning (50 and 6.4 this morning!) Other people will have very different experiences.

        • To Chris Hastings.
          If you read more you find that Fung saw a problem with high cortisol in ONE single participant. Not a general problem. Do you know about studies showing the cortisol problems to be general? I, for one, at 70 years of age, had no problem to lower my insulin and blood sugar through 5 day-fasts. Fat is not the villain if that is what you are trying to make it out to. It provides energy without blood sugar spikes, just in the same way as energy is provided to us through (short) fasting. Saturated fat is our bodies preferred way to store fat. Probably because saturated fats react the least to oxidants because it is the most stable fat type. It does not get rancid easily as monounsaturated and especially polyunsaturated fats. Meaning also that our brains – made largely by fat – become more resilient to electromagnetic radiation, well known to do its damage by breaking down structural fats. This was measured through an increase of the fat breakdown product malondialdehyde (MDA) in rat brains exposed to mobile phones! The control group had low normal MDA levels. If you keep talking using a mobile to your ear, at least make sure the fat you eat is saturated fat, the safest. We become built of what we eat. A good reason to avoid junk food.
          Common rat trials with “high-fat” chow make rats diabetic, a practical example that has made many researchers fully believe the thesis that “fat causes diabetes”. But only until they find out that part of the chow is sugar, 20%. Without the sugar, the rats won’t eat the chow at all, the manufacturer explained. Finally, since high fat is what we burn during fasting, eating low carb high fat before fasting days means smooth transitions, with low or no hunger. Same fuel, different source. BTW, fasting also clears out old and broken proteins and inflammations in the body, at the same time as the number of stem cells increase, also in older subjects as the number of stem cells determines our healing/repair capabilities. Hence very important that it is easy to commute between feasting and fasting. The high-fat food is key again.

          • You did not comprehend his article..I am one who suffers from high cortisol and IF does NOTHING for me.. however after reading his article I started eating every 2 hours and my blood sugar is now normal.. he said one size does not fit all It obviously fits you but not me or the dozens of others he spoke about…. and I did not get that fat is a villain in his article…

  6. My fasting blood sugar is 300 reduced to 250 but my doctor says I have low blood sugar. I already fainted at work for not eating for more than 5 hours-though I asked the Boss to let me go as I’m
    Not feeling well, she thought I was faking it.

    • You need to change doctor. Fasting blood sugar over 135 is definitely diabetic. Then mix in much more fat like butter, bacon and coconut oil in your meals for several days or best a week BEFORE fasting. Good Luck!
      Also Read Jason Fung’s blog here

      • Dr. Fung fixed me. Haven’t had diabetic meds in almost 6 months and my A1C runs consistently in the low 5’s. Don’t have fatty liver or fatty pancreas anymore either.
        Type 2 is not in remission, it’s gone.

        • Hey there, I’m starting to follow Fungs instructions on fasting cause I’m a newly diagnosed type 2 diabetic and I’m in my 20s. Is there anyway I can talk to you about this, maybe help clear up some confusion I have or gain some encouragement. No one supports my fasting because they don’t know anything about it.

          Thank you

          • Lyn, read more of Fung’s blog posts, the comments and maybe also buy his book, The Obesity Code. It is also available as Kindle.

  7. Could it also be that they are going in and out of ketosis. The ketones are stimulating beta cells causing a hypoglycemic reaction and then the liver kicks in with gluconeogenesis? Never adapting.

    • No ketones at those high bg readings. Fatty liver that will keep pumping out bg until it is “empty”. May take 5 days fasting. Just keep monitoring bg. To be able to fast 5 days you must eat LCHF for at least a week before, then hunger will disappear, almost magic!

  8. Sten, Hi. I am a Type II Diabetic and have stopped insulin since I viewed Dr Jason Fung’s Youtube videos. I have managed to lose 11 kgs weight over the last 7 weeks . I am following the interval fasting method and other than a cup of tea or coffee for breakfast I have my first meal at 13:30 followed bymy 2nd meal at 19:30. While my fasting sugars are now in the 120s my waking up levels are in the 140s and the post prandial 2 hours are also in the 130s.
    My afternoon diet consists of diced vegetable salad with olive oil and lime and vinegar.
    My evening meal consists of either an omlette or vegtable soup or a piece of roast chicken or grilled fish.
    My BMI currently is 25 from a peak of 29.3.
    What should I do to have a better blood sugar profile and also reduce my glucose sensitivity ( If I take a pear or an apple or pomegarnate my postprandials shoot upto 180mg).
    Look forward to your guidance.

  9. I’m 62, have stage 3 adrenal fatigue with reactive hypoglycemia. Taking 20 mg. of hydrocortisone daily. If my blood sugar falls below 105, I’m shaky, confused, depressed, horribly drowsy.
    I have decided to just let my BS stay at 105, since I’m 62. I’m in a comprehensive adrenal repair program, including gut healing, paleo diet, Dr. Wilson’s adrenal repair supplement program (since May 2016), low stress (retired), living simply and low stress lifestyle. I had to stop thyroid meds because they were causing dizziness and depression – Mary Shomon says that’s a sign of too much thyroid medication.

  10. I had a horrible doctor who told me to eat every 2-3 hours paleo and it made me much worse and my blood sugar skyrocketed. It got better once I started adding more carbs and fiber, but my blood sugar is still a little above 100 and I have not lost any weight at all. I have had 15 horrible doctors now (NDs, DCs, integrative and MDs-they all suck)! I was diagnosed with stage 3C advanced adrenal fatigue back in 2014 and it has improved but my blood sugar/insulin is still an issue. I have tried every diet and read every book from every “so called” doctor who wrote a book about something they know nothing about and I can tell you that NONE of their diets/books work at all! so frustrated!

    • I’m EXACTLY the same Stepanie!!! I hear you loud and clear. I’m doing (have done) tried everything under the sun. Been on a paleo diet since 2007, still have elevated cortisol, high blood sugar – especially on waking (called the Dawn Effect), and just cannot lose the 25lbs around my stomach. So frustrating.

      • You will feel better and be warmer by eating more carbs or more in general, but insulin resistance and weight gain will return. It is the insulin resistance in the bottom of it that makes the difference and it has to be lowered long term. Unfortunately too much arbs and too much proteins makes insulin resistance worse long term. The very reason so many people today are where we are, too much fast carbs in the food over too many years builds it up. Once it is low enough whatever extra food we eat makes us warmer. Read how to do on Dr Jason Fung’s blog. Intermittent fasting worked wonders both for my weight and heart disease! Still has slightly elevated morning sugar, 5.5 sometimes. Before it was often 6.5 and over.

        • Sten you’re talking nonsense.
          Kempner provided in the early 70’s the carbohydrates increase insulin sensitivity.
          The issues arise when consuming too much of the wrong types of fat.
          Fat blocks the insulin receptors, inhibiting your bodies ability to pull glucose from the blood.
          High blood-sugars is a symptom, not a cause.

          • Matthew,
            You may want to provide citations to support this view to start a conversation about it. If you would kindly refrain from negative comments that would be appreciated.

            • Thanks Martha, at least a starting point. I usually refrain from responding to insults like those supplied by Matthew. To keep a a decent discussion a decent moderator is required. What happened here?

        • Stem, did you mean to write “too many carbs and too FEW proteins”? This is what I’ve always understood the problem to be.

          • I am reactive hypoglycemic, Hashi’s. I am non-functional if my blood sugar is below 105 – dizzy, depressed, confused, comatose drowsy. I’m 62 – eating autoimmune paleo, exercising, no alcohol, supplementing wisely. I think a life-time of the standard American diet got my body so used to a high level of sugar that it simply will not accept lower than 105, so I’m just going to live with that. I might feel differently if I were younger and had a family to support.

          • Hi Par. No I did not. Both carbs and proteins need to be cut back. Reason Atkins fail after a year or less is that excess proteins are converted to glucose by our livers… , having same net effect as excess carbs. Another reason to cut back proteins is to promote health = maintenance instead of growth, once we have matured. Else we can easier get cancer and not keep our cells clean from breakdown debris. Ron Rosedale has some clarifyng presentations about it (mTor) and Jimmy Moore sorted out his last weight problems by cutting proteins. Intermittently at least down to 0.5 g net protein per kg lean body weight. Yet a 100g beef stake is about 28 g net protein. Cheers!

      • I was prediabetic for years and thought cutting carbs would help. Apparently I did not cut enough and went on to develop T2D. I started a low carb high fat (LCHF) diet combined with moderate exercise and the pounds are melting away. My blood sugar fasting 70-80 range and post meal numbers are below 100. I have had no BG spikes since going LCHF and the “Dawn Effect” disappeared all together. I feel better than I have in years.

        • That exercise is key as you are dumping glycogen and then refilling the body stores instead of it floating around in the blood.

          • Agree that exercise is a key. Yet intermittent fasting IF can have same effect on blood sugar. Of exercises, HIIT is the most effective from two points. 1/ No wear down of body joints as with longer distance running, cycling etc..
            2/ Uses glycogen to build muscles long time after each pass of exercise. Yet IF has another advantage: It triggers autophagy, our bodies only known cellular “garbage collection/recycling” system. Combinations are of course also useful!

            • I’m having a hard time with my fasting blood sugar in morning (dawn phenomenon). I’m working on intermittent fasting and LCHF. From what I understand, IF is more effective since your body is in repair mode. I also really think there is a problem with a malfunctioning liver unable to regulate glucose in the morning. Being 49, I have to realize my body has less control over its hormones, I have less muscle mass, and need to find the appropriate diet and IF to control my blood sugar. Insulin and diabetic drugs are terrible on your body and will try my best.

        • Hi Sharon, that sounds like my case..when I was prediabetic for almost a year I thought I was cutting back and eating right. But unfortunately it wasn’t enough, I’m now a type2 diabetic.. in my opinion our doctors don’t do enough to help us in the right direction until it’s too late..

          • I’m 62, have stage 3 adrenal fatigue with reactive hypoglycemia. Taking 20 mg. of hydrocortisone daily. If my blood sugar falls below 105, I’m shaky, confused, depressed, horribly drowsy.
            I have decided to just let my BS stay at 105, since I’m 62. I’m in a comprehensive adrenal repair program, including gut healing, paleo diet, Dr. Wilson’s adrenal repair supplement program (since May 2016), low stress (retired), living simply and low stress lifestyle, walk 2 miles daily. I had to stop thyroid meds because they were causing dizziness and depression – Mary Shomon says that’s a sign of too much thyroid medication.

            • I need help! My morning blood sugar is always high. 160-200. Will intermittent fasting help me? If so, how long will it take to go down? I don’t know if by fasting I am belong or making it worse?

              • First reduce carbs and increase fats including saturated fats like coconut oil and butter. Bu “fat adapting” fist it is easier to sustain the minimum 3-day water-only fast that can reduce blood sugar into the 70’s and below. Repeat 3 days a week and eat “normal” low carb rest of every week. Plenty green vegetables, organic if possible, when refeeding. Add 1/2 lemon to two quarts of clean water helps to quench all types of cravings during the fast. No limit!
                If fasting more than 2 days, then add bone broth with plenty of salts every day to maintain electrolytes.
                Good Luck!

    • Hello Stephanie
      I can understand why you feel so frustrated and hopeless.
      I don’t blame you.

      Not sure if you’d be interested in another book or not…but it tells you to do things differently in this one. It is written by a Canadian nephrologist in Toronto, Ontario.

      He has a weight management clinic (by physician referral only) as well as a distance management clinic.

      But what I wanted to mention to you is his book which was just published this year called The Obesity Code.
      His name is Dr Jason Fung.

      I am in no way affiliated with him, but I have read his book, seen him on Youtube and subscribe to his email blogs and I think he is telling us what we need to do, which happens to be the opposite of what we have been told for decades.

      The book is a great read.

      Good luck Stephanie!


      • Agree 100%. Search the blog text here with Fung. So pleased to see that several others also have found him!. And I have read the book too. Great read.

        • Hello Sten
          Glad to have your opinion!
          I am also very much a supporter of Dr Fung and enjoyed his book so very much ~ it makes so much sense.
          And having a specialist, who is engaged daily by multiple cases of kidney failure and other conditions caused by diabetes, he has my trust. His experience is direct, long standing and is accompanied by extensive teaching; his ability to see first hand and to access and also compile his own statistics and facts only adds to the unique perspective he has, and serves to validate his medical opinion.
          It is indeed a ‘great read’!

      • Dr Fung does Ketogenic diet, which I have done already, but the keto diet makes me feel horrible and I think it has to do with the low carb because I had severe adrenal failure back in 2014 and am still recovering. I’m not sure that it is safe for someone with adrenal issues to go low carb since it can send us crashing again? Any thoughts? Anyone who had severe adrenal fatigue get better from low carb/keto? When I say I had tried everything, I mean I have tried EVERYTHING!

        • Stephanie

          Dr Fung is a nephrologist.
          He has a website and takes questions.
          Please try to do a search on his blog site~ I did write in one time and he did answer me.
          He also has an assistant as well.


          Give it a try, you have nothing to lose and a whole lot to gain!
          Please keep me posted Stephanie~ I’d love to hear from you.

        • Stephanie~ Not knowing where you are, but perhaps one of these affiliate practitioners would be near to you.

          Otherwise, you can do the distant program they have (for a cost)

          Regardless, please, give the book a try. There is more to it than a ketogenic diet…much more!

        • Eat Stop Eat. Or Intermittent Fasting. Anything that causes you to eat less calories than you burn WILL over time reverse your type 2 diabetes.

          The fastest way is a crash diet of ~600-800 calories comprised of at least 70-80g protein (to help you spare lean muscle mass losses), maybe 5-10g of essential fats, and the rest in complex carbs.

          Ref: http://www.ncbi.nlm.nih.gov/pubmed/21656330
          Ref: http://www.ncbi.nlm.nih.gov/pubmed/3976553

          This forces your body to burn the fat in and around your liver, pancreas, muscles, and other organs that are causing the insulin resistance.

          As this fat is burned up you will see progressively better fasting insulin numbers until you are completely NORMAL.

          Congratulations you just reversed your insulin resistance and type 2 diabetes!!

          Now go as close to whole-foods plant-based vegan as you can while maintaining low amounts of essential fats and you will not only maintain your health, you will increase your longevity — just like the traditional Okinawans.

          • Disagree strongly as it is same as biggest loser and is therefore bound to fail just as they did: Within months the wight is coming back and the diabetes at the same time. Unless you accept to freeze and feel miserabl for the rest of your life. This is the reason banting like this ends fails/ends up in jojobanting. It does not matter. Maybe if you go to extreme and remove all fat it may work. One method is to water fast for up to 5 days or until BG is just over 3, followed by low calorie high fat and low insulin driving meals (keto diet), once a day for instance. The fast empties the liver of gycogen completely so there will be no more “high morning sugars”, and it also sets down the insulin level allowing fat burning from day 1 of the diet. Best induction is to start with the keto diet a week before, as it is 100x easier to fast without cravings than with ! The fasting is the reason GBP operations work in the beginning: The days before and after consists of 5 days fasting and that drops the Blood Glucose and insulin to normal and no insulin required any more ! But also GBP’s fail for the same reason people become diabetic -2: Too much refined carbs in the diet.

        • Stephanie you are correct, keto Genesis is awful for anyone with adrenal failure. A low carb diet causes cortisol to rise and this is awful for anyone with adrenal failure or hypothyroid. The ONLY thing that has worked for me is slow burning carbs like, quinoa, beans, and lots of fiber along with healthy proteins and fats. No sugar . This is the only thing that works. No eating three hours before bedtime and plenty of water. Stay away from low carb diets. Bad news for people like us.

          • Shawna,
            If you refer to the study entitled “Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance”, it was not really a finding that cortisol increased on LCHF. Cortisol reduced in all groups, but least in the low carb group. Hence no increase cortisol from low carb.
            It is also well known that high protein intake increases cortisol.
            Unfortunately protein was not kept constant in all 3 groups, but was highest, 10% absolute higher, in the low carb group. Instead of testing a LCHF diet, the low carb diet was more like an Atkins diet, something that failed years ago, due to too high protein intake, it is widely believed. LCHF stands for lowered carbs, increased fats and unchanged proteins. Still all people do not thrive on the same diet, and although high protein diet in general is implicated for cortisol increase, I have seen no evidence that high fat increases cortisol in general or on average. If you have, please post a study link! Yet we are, thankfully, thriving on different diets.
            Here is one elaboration by Peter Attia. http://eatingacademy.com/books-and-articles/good-science-bad-interpretation

        • Stephanie,
          You may be interested in reading Dr. Sara Gottfried’s book, “The hormone reset diet”. She is a brilliant women’s health physician and discusses reasons why the keto diet and paleo do not work for some women. It’s all about the delicate balance of hormones. Have you tried taking adaptogen’s for adrenal fatigue? I would recommend Adaptogen by WTSmedproducts.com.

          • I am way ahead of you. Already tried Sara Gottfried’s book on hormonal reset and it didn’t work for me either (followed it exactly for over 3 months and still eat that way). I also do adaptogens as well and they aren’t working. Gottfried isn’t that brilliant as she is missing a lot of info in her books and references doctors (who I’ve been too) who aren’t that good either. I have other health issues (SIBO, adrenal fatigue) but doctors aren’t listening so I am navigating this road on my own.

      • Dr Fung is part of the reason I tried LCHF. That diet is totally working for me, and I am not on any medication.

    • Read John McDougall’s Starch Solution. This will be the one doctor that can cure all your problems

  11. I think this article is accurate. Cortisol also raises blood pressure. Whenever my elderly mother wakes up, it has usually been over 12 hours since she has had any food or drink. And her blood pressure is usually rather high, such as 170/95. But as soon as she eats a meal, it drops dramatically, often to something like 115/70. She’s on a very low-carb diet as well. So, I do think cortisol is the culprit. Apparently a drop in blood pressure after a meal is common among the elderly.

    • Could a glass of water on awakening have the same effect in lowering morning blood pressure? I am heading for 70 next month, seeing a few more visits to the loo now than years ago; meaning that we may not recycle water as good as we used to do when we get old. The supreme water recycling example would be the hibernating bear, not drinking or peeing anything for months! Has less water, thicker blood, higher blood pressure any bearing?

      • Great question, Sten. I’ve tested this on my mother. Although I do think water thins blood, I haven’t noticed that big a change in her blood pressure after she drinks some water upon awakening. OTOH, after a meal, the change in her blood pressure is dramatic. I’ll have to test it some more, though.

        • Sam – Could it be that when seh eats her breakfast is the time she takes her meds and its the meds and food combined that has this effect, same with my father.

  12. Hello,
    I think Dr Jason Fung would disagree for at two reasons. First is that IF is probably one of the few ways to cure a metabolic syndrome, the root cause of poor blood sugar regulation. Secondly because he means that the reason for increased blood sugar during fasting is “a liver full of fat and glycogen”. We know that high insulin stores sugar in the liver and prevents the liver from delivering glucose into the blood stream, (and prevents fat burning..). Low insulin does the opposite, and during fasting insulin drops (all relative to ones personal levels), which means that the liver opens up glycogen stores and blood sugar goes high. Same thing every morning.., but less. After a few days fasting, in my own case, (pre-diabetic) my morning blood sugar dropped every day. For a 4 day fast, it started in my case at 5 first morning, then dropped to 4.4, 4.2 and 3.8 over 4 days. (I had done one meal per day for a week before, reason for the good start value I think) Fung has an excellent article about morning sugar. Google Jason fung dawn phenomenon to find it!

    • hi there: Can I ask you how many days could it take to drop sugar readings while fasting? I have done 2 days so far and my fasting sugar levels are 147…however I want to commit fasting at least 5 days for 14 hrs in a row at a time…i expect sugars to start dropping by my next reading (tomorrow) im on a LCHF diet as well, I would appreciate your answer


      • Since you are only fasting 16 hours in row it will take longer than if you water fast for 24 or 48 hours at a time. For each stop it may take up to 8 hours to get back where you were, blood sugar wise. The fasting time it takes to get back normal fasting blood glucose depends hence on how long periods you fast, your initial fasting blood sugar readings which is related to how fatty or even enlarged the liver is starting out, or how much glycogen and fat it stored starting out. But one fast at a time will get all back to normal. Morning blood sugar is the simplest indicator of the liver condition. But if you took alcohol night before, blood sugar is down due to that liver becoming busy cleaning out alcohol instead of making sugar. A false good!

        If you decide to do water fast, please start with only 24 or 48 hours and feel yourself forward. Increase a day at a time, if you need to increase at all. One meal per day over a week is almost twice as efficient than 16/8 or every 2nd day, as the time when no food left is around 16 hours per day then, while only 8 on 16/8 and 16 per 2 days on every 2nd day. With longer fast there is room to eat more when not fasting, which helps metabolism to stay up. Lunch to lunch or dinner to dinner is what I started out with.

        • Stin,
          I tried a fast and was going for 48 hours. I was perfectly fine for the first day. BG levels 70 fasting-max was 92. I even did some weight training and felt great.

          On day 2 BG was 71 and as the day went on I started going hypo lowest reading was 63; so, I broke the fast and added a little bit extra carb than I would eat for a normal meal. My 2 post parandial GB was 84.

          I’m not sure why I went so hypo. I’m still 26lbs over my goal weight–so, I didn’t anticipate my GB levels going into the 60s. That’s just too low….Any thoughts?

          • Sharon, thanks for the comment. If you got dizzy or felt weak, I can only guess, but if you felt fine it is a natural thing. BG drops as ketone production increases and roughly the sum remains the same, I read somewhere about it. I felt even more energized when BG dropped to 3.3 mmol/l day 2 or 3. It makes sense as ketones burn more efficient than BG. If you felt bad with low BG my guess is that you need be better adapted to burn fat. Easiest way is to reduce carbs and increase fats while not fasting. Cheers and Good Luck !

            • Thanks for the feedback Sten. I’ll research more about the information you provided. I felt perfectly fine when BG dipped low, but didn’t want to go much lower than that!

      • I’m in the exact same boat. I’ve been fasting for two days and my blood sugar has gone up to 143. A week ago my fasting blood sugar was in the 80’s or 90’s. I’m now in diabetic range and very nervous about it. Will it self correct?

        • After 3 days water fasting ( zero calories, forget Mosley and others) Mu fasting BG had gone for 6.5 to 3.8. After 2 days it was around 5.
          Don’t worry, when the liver is full with sugar (and fat) it takes some time to empty it. The so called “physiologic insulin resistance” is a brain ghost invented by carb lovers. Eating carbs the night before helps, as it keeps the insulin high so that the liver will never empty excess sugar. A safe route to get or prolong DB-2.

          • Thank you Sten! I tried another fast and the same thing happened my blood sugar keeps going higher and higher The longer I fast. It seems like everyone else’s sugar is coming down. The higher it goes the less it comes back down. I’m not sure how to proceed.

            • Did you really water fast ? Minimum 3 days !
              Maybe your liver is very swelled taking even longer to empty the glycogen in store?
              Unless it is empty during fasting blood sugar will remain high.
              Daily walks/exercise will consume energy and will this speed up the process.

              • Yes I actually did just water. I got my doctor in on the action and he said that he has absolutely no idea why my blood sugar’s are going up with each passing hour of fasting. As far as exercise I usually run for an hour every day. Interestingly enough my blood sugar goes up after exercising as well. I wish someone had seen this phenomenon before and knew what I could do about it. I’m an RN and have asked all the doctors I work with and they’ve been testing me my A1 C is 5.2 but they have no idea what’s happening. They said not to continue to fast because it just keeps going up and up when I do so.

                • Lee, how many days in a row did you fast ?
                  3 – 5 is needed, just 1 or 2 is not enough to “turn the tide” of glycogen flushing out glucose from the liver in the wake of lowered insulin.

                  Many people “turn in the door” when they see BS going the opposite they expect from fasting, but that’s the way it works:
                  It goes up before it starts to go down. And when it reaches 3.5 it is usually perfect as the sum of the BS and ketones then make up your well being.

                • Hi Lees,
                  The most obvious variable that I notice is that you are exercising too much. When you exercise for greater than 15 minutes, your body responds by increasing cortisol. Cortisol is the natural form of Prednisone ( which usually causes weight gain and high blood sugar, as you probably know ) If you are trying to burn fat long term, you should immediately stop running and switch to high intensity interval training (HIIT). I would recommend that you research the Tabata Protocol; in a nutshell, you go full force for 20 seconds, rest for 10 and repeat for 4 minutes. Sounds too easy but check out the data from one of Dr. Tabata’s research articles (http://link.springer.com/article/10.1007/BF00357597) . There is not a one size fits all answer to any medical issue and you may need to do more experimenting. Good luck!

                • Thank you Martha! I think the high-intensity interval training is a great idea. I’ve heard that that’s the best thing for trying to burn through my sugar. My problem is with the fasting if I don’t eat the second I get up and every few hours my blood sugar just keeps going up that’s what we’re working on. Three weeks ago my fasting blood sugars were anywhere from 70 to 90. We are trying to figure out how to get them back down so…. we tried the fasting, (we meaning me and my doctors) They both said that it should go down with the fasting and it just keeps going up. My A1 C is 5.2. I was just wondering if there was anyone else out there that had the same experience. My fasting blood sugar this morning was 125. I was told my insulin is working because after I eat within an hour my blood sugar is back down under 120. However I cannot get it to go much below that. Just looking for answers.

                • As
                  Jason Fung has explained, FBG can keep going up for several days during fasting. It is the lowered insulin that allows the stored glycogen out from the liver. It is a good thing ! I.F. speeds up the process of burning that sugar. After 3 days my BG finally landed around 3.0. Lots of energy then as “the rest” then was ketones. But you must do WATER FAST. No few 100 calories except taste ( of lemon) allowed. GOOD LUCK!

                • Would you mind telling me where Jason Fung says it’s OK for your blood sugars to keep going up with fasting. I’ve looked all over his literature and haven’t seen anything like that. That would actually make me feel much better because the doctors here said to stop until we figure this out. They have many patients that are fasting but none of them are having their blood sugars rise like this. They usually go down. I can’t keep having them go up higher and higher and not come back down.

                • Fung writes about it in the “Dawn phenomena” here:
                  The article explains why it is a good long term solution to allow a short period of blood glucose rise during a fast!
                  Often it instead recommended to suppress dawn phenomena with more carbs in the evening, extra insulin or tablets. But this has instead a long term disease worsening effect as it cures the symptom but leaves the root cause become worse. Once the glycogen is emptied I understand that the liver also starts to metabolize some of its fats and making even more glucose in the process and I am not sure how long this process can go on for a diabetic-2 with a liver maybe twice as large or more than a normal liver. But the size is probably a good clue to the time scale. On the other hand most diabetic-2 going through GBP have according to studies I have read about normalized their insulin sensitivity and are insulin free after about 5 days of compulsory fast accompanying the operation. Before to empty and after to heal. That’s all it takes to cure diabetes-2! The operation is there to keep patients from falling back fast, as they are regarded unable to quit carbs (?) But starting off with a ketogenic diet the initial water fast becomes easy to start as fasting is using the same type of fuel as a ketogenic diet (fat) , but from the body instead of from food. Follows there is no need for a hospital regiment to do the 5 day fasting to normalize insulin sensitivity and blood sugars out of the diabetic range!
                  Added advantage is that it is easy to retain the gains once outside the maze of sugar dominated nutrition and familiar with IF. Ironically people that have done the GBP are now often given better dietary advise, but after the operation…. Please let us know how you get on!

                • Hope to help and sorry in advance for my english. From what I understood long session of endurance training like you probably did are also a big stress forse the body (like fasting) and it can rise your cortisol level a lot, resulting in rising the insuln level

                • Regarding insulin: I do not know about cortisol levels but my fasting insulin went from 8 to 5.3 measured a few weeks after 3 fasting sessions 4-5 days each.
                  Read Jason Fung’s blog for really good information about insulin and fasting!

  13. I’m wondering if anyone can help me with weight loss resistance. I’ve done pretty much every diet including IF, have FBS in the 90’s and lower 100’s. I’ve gained 30 pounds in 3 years without changing my diet or exercise habits. I eat organic, clean, vegetables and protein. I do not eat any refined carbs or processed food. I’ve even tried levothyroxine for a year without any success.

  14. Great information! I am exactly one of the people Chris is mentioning with already on a paleo, low-carb diet, and active individuals having issues with blood sugar regulation. Only recently have I been experiencing episodes of reactive hypoglycemia and after having blood work done, I learned my ab1C was 5.7. I have started testing my BG levels in the morning and post meals where my fasted BG are consistently in the 90-115 range. However, after meals (45min and 90 min readings) they hover from 110-120. If cortisol dysregulation is the culprit for higher fasted BG levels, what steps can I take to lower my fasted BG and maintain healthy levels throughout the day?

    • I am insulin resistant and the only way I could get my numbers under control was no grains at all. I also don’t eat starchy foods. I started intermittent fasting and my blood sugars are now regulated.

      • Caffeine can raise cortisol (in turn raises BG) so cut the caffeine out. I’m working on getting myself to an ideal weight and maintaining it. My logic is fatty liver. You could also have a lot of glycogen in your body.

        • Mike – How are you doing with fatty liver? Thanks for mentioning the caffeine to cortisol to BG connection.
          Ive done IF for 6 months to a year and feel jittery and more anxious in the am/afternoons, probably the caffeine as I do coffee enemas in the mornings.

    • “Great information! I am exactly one of the people Chris is mentioning with already on a paleo, low-carb diet, and active individuals having issues with blood sugar regulation.”

      So, the question remains, “How’s that fad diet working out for you?”

      Listen people, if you are causing more health problems by doing things that purport to “fix” health problems, stop.

    • decrease cortisol secretion by eating regular meals throughout the day. Stop the fasting. It works for some, usually men, but doesn’t work for many. It’s making your glucose levels worse.

      Continue regular exercise, eat mostly whole foods diet.
      Lots of organic non-starchy fruits n veggies. Some fruit, lean protein and some healthy fat, plenty of clean water.

      Most importantly, manage your stress levels well. Use whatever brings your stress levels the best. Music, massage, hot baths, workouts, meditation, yoga- it depends on YOU and how you best respond to stress management techniques.

      Many Blessings,


  15. I have found the articles extremely interesting and I am very much hoping this may help me.

    My scenario is this:

    I am on the paleo diet and have been for 4 months. I take insulin, about 20-40 units a day. I have virtually no carbs most days. I wake with blood sugar at 125-150 or more. My normal wake up is at about 125. The issues are that by 12pm, I will have blood sugars that rise to 170 +, without any food. Added to that, if my blood sugars are at 150 at 7pm, most times it will rise to 165-185 by 1:00am, no carbs or no food at all. I have tried metformin. No changes at 500mg using long acting metformin. I have tried so many things my head spins. I refuse to give up and just take more insulin. This condition is getting more difficult to control. Any help would be immensely appreciated. Thanks….

    • Tim. I am having this same set of symptoms. I think I have identified what it is, but I don’t have a solution. Some people will tell you to eat an evening carb snack. No. That is not the solution. I think this is an adrenal problem. It may not be a “problem” it may be a normal adrenal response to fasting or zero carbohydrates. The adrenals are sending a stress response to the liver, and by gluconeogenesis the liver is keeping your blood sugars up. The solution is to de-stress your adrenals. And good luck with that. One stress could be zero carbohydrates. You could start adding back some essential carbs–like greens, mushrooms and other vegetables. I read that berberine in addition to metformine can help high fasting blood sugars. Good luck!

      • Gloria –

        I think you hit the nail on the head. I have adrenal insufficiency. At night, when my Cortisol would be lowest, my otherwise normal blood glucose levels would soar. I suspect the liver was responding to the stress of low Cortisol by pushing out sugar as a substitute (glycogenation).

        Then I was given Hydrocortisone to supplement for the low Cortisol. Suddenly, my usually normal day sugars and A1C rose, and before you knew it in a year I was diagnosed with T2D.

        Frantic, I weaned myself off the Hydrocortisone, and was started on Metformin. Blood sugar and A1C lowered, but as the blood glucose levels lowered my Cortisol levels plummeted.

        So for people like me, the dilemma is this: Too low Cortisol raises blood glucose levels to compensate for the adrenal insufficiency, and the amount blood glucose is raised depends on the severity of the adrenal fatigue. But paradoxically, too much Cortisol drives blood sugar levels up as well, inevitably leading to insulin resistance and, overtime, T2D.

        Have tried Paleo, Low carb, high fat, and variations of all to no avail, with each leading either to low adrenal function or high sugar release, or both. Also tried Intermittent Fasting, which is a solid approach (Dr. Fung and his group are a great resource), but the Cortisol levels got drastically low and the blood sugar (glycogenation) compensated by soaring again, especially overnight. Hard to believe there could be that much fat/sugar stored in the liver, but I guess it’s possible.

        Anyone have suggestions?

        • Check your fasting insuiln levels. Once below 6 most of your night and morning blood sugar spikes will vanish. To get it down there is only one way. Periodical fasting. It is also made very easy to fast a few days in a row if you first reduce carbs and increase natural fats for a few weeks first. Hunger pangs will go first. Good Luck.

    • There is a new group of doctors out there who say that taking insulin is like giving alcohol to an alcoholic. If you google Prof Tim Noakes and nephrologist Dr Jason Fung, you should be able to find out more.

      • Well you can’t just stop taking it! Even on insulin, my fasting sugars are in the 250’s. When I eat LCHF & IF, I’m lucky if they run 140’s + insulin. I’ve tried adding back a little carb – shot them up even higher – stopped that! I’ve tried eating 12/12 so I have a high fat/moderate protein breakfast in the morning and a Keto dinner. They came down during the day but fasting was still 250’s.
        I laugh when all of you worry about 110 as a “high” blood sugar – I’d kill for that.
        I exercise to muscle failure 3x/week and walk every day, usually a HIIT walk for 30 minutes. NOthing is working and I’ve read Fung’s website and book. I think some of us are just destined to die of metabolic syndrome.

        • Hi Janni,
          One needs to water fast for 3 days to get blood sugars down under 100 when they are as high as yours. In the beginning FBG goes up because the lower insulin from no foods allows more sugar than otherwise to be released from the liver. But starting out on LCHF is a great advantage as it makes the “impossible fasting” so much easier. It takes you past day 2 and after that it is easy. Don’t go more than 3 days first time. And read up Jason Fung’s blog for gradual re-feeding with broth etc.

          • I’ve also read most of Dr. Fung’s info and like Janni would love to have BS in the 100’s…I water fasted for 2 1/2 days and my bs never went below 189, remaining between 219 and 240 for the entire time. I began eating again out of frustration, am I being too impatient? Does something magical happen at day 3? I don’t take any meds as they all disagree with me. I’m Type II from gestational DM 6 years ago…it seems so hopeless. I’m doing keto for the last 4 days and again, 210 is lowest it will go… I do know I need to increase my activity–it was 210 after Taekwondo…I’m adding HIIT tomorrow but would appreciate any specific words of encouragement or understanding of how long I should expect to go before seeing results. Thanks so much and thank you for this forum!

            • Nothing magical happens. But after 5 days GBP patients have normalized blood sugar and insulin levels. They get it only through fasting, that is compulsory before operation to enable it and after to allow to heal.
              You do the same and you are there.
              And yes, BG keeps rising before it drops, because the liver is 1/ usually packed with glycogen and fat 2/ usually a lot larger for diabetics meaning a longer time to empty it.
              Adding HIIT and exercise speeds it up of course as then more of the liver energy is used up instead of raising blood sugar.
              Good Luck Now !

  16. Hi Chris,
    I am 34 and was diagnosed with Type 1 diabetes 18 months ago. Shortly after diagnosis I switched to paleo and low carb and only require occasional insulin if I have a high carb meal or for a few days each month around my period when my fasting blood sugar tends to be higher than usual.

    My problem is that when I take the long acting insulin I feel physically edgy and my body is tense all day long even though my blood sugar levels are normal. This happens even if I take long acting insulin outside of the time of my period.

    I am wondering if this is related to cortisol dysregulation? It does not occur when I take rapid acting insulin such as with a high carb meal and when I’m not taking long acting insulin I feel great!

    For months before and shortly after diagnosis of Type 1 diabetes I had this same constant nervous tension (even before I went paleo/low carb so I haven’t linked it to my diet). No one was able to shed any light on it for me and the only test results that showed anything were that my salivary cortisol levels were very high all day long. I have only recently linked this same feeling to when I take long acting insulin so I believe it is somehow related to autoimmune/diabetes.

    I have had no luck in getting any insight from my endocrinologist so any help would be much appreciated!

    • Vitamins and minerals are very important to make hormones such as insulin , thyroid , etc . Just following a paleo diet many times is not enough , because most diets , even healthy ones are deficient . We need to get adecuate amounts of calcium, magnesium and potassium every day ! Also zinc and selenium are very important. And make sure to get methylated b vitamins , especially if homocysteine levels are elevated. All this helpes to regulate sugar . Some people also have a defective gene and don´t make enough cortisol , which makes it harder for the body to regulate sugar levels.

  17. I’m a 69 years old male, I’m on hormone therapy combating prostate cancer. My fasting glucose level, is between 90 to 97. The side effects of hormone therapy is weight gain and increase belly fat. I also think that it has effected my glucose level, like increased it. I am hoping that IF, can offset some of these side effects. I am vegan, no meat or dairy.

    Will IF help as I hope? I just started the eating plan, yesterday, with a 16hr fast. How long do does it take to see some measureable effects, if there is to be?

    • Dale. What intermittent fasting really does is reset your insulin which may be off from following a high carb junk food diet. You may not be a candidate. It looks like your “problem” is really an effect of the hormone therapy. Is there any way you can work with your doctor to cut back some on the therapy your are doing? And check with your doctor to see if fasting might interfere with the therapy. (Make sure he isn’t just giving you a knee jerk reaction, Oh fasting! That can’t be good!)
      Your fasting blood sugars are ok, probably healthier to be in the 80s, rather than the 90s. As you say they may be running a little high because of the therapy. If you want to try IF you should see results in a few weeks. And results would be slightly lower blood sugar, and less belly fat. You will be burning fat instead of glucose. Also, you want to eat a variety of good fats (oils, nuts, seeds), along with your regular vegan fare.

      • Hello Gloria and all of you IF people, just wanted to give an update on my progress after using the IF method to reverse my type 2 Diabetes, I’m so happy to say that my numbers have changed dramatically. My fasted blood sugars were out of control (over 300) and now since I’ve gotten on the IF diet, my numbers are no more than 120 and sometimes under 100. I have to admit it does take work for your body to adapt but it eventually it will, combining HIIT (high intensity interval training) workouts, along with IF and a fully committed KETO diet, you will be amazed at what you can achieve. I wish that some of my closest family members that have deceased because of Type 2 Diabetes would of known about this, they never stood a chance, I just feel so blessed that I found out how I can fight back and “kick type 2 diabetes ass”. I currently feel “leaner, faster and stronger than ever. I thought I could never stop drinking soda and now I don’t even crave it lol. I can’t wait for my follow check up with my Dr and brag about my numbers because he thought that my diet was extreme and immediately wanted to put me on insulin, Actos and merformin. But I declined I told him let me try my IF method and if this doesn’t work then i guess I’ll have to start heavy meds, so 3 months later “bam” Don’t need those meds, I stayed with metformin but to be honest with you guys, that pill really doesn’t make a difrence so when I go back I’m going to tell my Dr that I want to try 3 months without metformin or any diabetic medication to see my results. Here’s my iF process on mon, wed and thurs I hit the gym at 6am I combine weight training and cardio with HIIT workouts, 9:30 i’ll drink my black coffee and won’t eat until 2pm, then my last meal at 8pm, but before all that you need to consider watching your cortisol levels and also monitoring your sugars 3 times a day, to see what foods really spike up your sugar, but anyway just giving you guys my update and I hope someone here will take the time and read this to be as blessed as I did, to learn this knowledge, thanks guys and good night.

        • Wow! Arod. I am impressed. Shows what can happen when you take reversing diabetes seriously.

          One question: Watching cortisol. How do you do that, and what do you do if your cortisol is running your blood sugars up?

    • Update from my previous post. Two weeks after I started an IF regimen from 6pm to 9am, I check my blood glucose. I was consistently over 90 and my first check this morning I’m at 74. Hopefully, I can contribute this improvement to the new regimen. Its never since I have been checking has it been that low.

      • Yesterday I listened to a presentation between Brian Mowl (diabetes educator) and Dr. Jason Fung. Fung is a proponent of intermittent fasting. I tried intermittent fasting and essentially reversed my Type 2 diabetes. The only remnant is high morning blood sugars. I am inspired by what Dr. Fung said yesterday: Its a back log of sugar. Just keep fasting and eventually you will use it up and your body will be normal once again. Dale, I am envious of your 74 morning blood sugar. And I am going back to my fasting routine to see if I can accomplish the same. Who knew that that curing diabetes could be that simple?

        • Gloria, I am seeing my step brother today. He has type 2 diabetes, his glucose values are over 300. How much of an impact can IF have on a guy like this? When you were type 2, how large were you glucose numbers.

          • Dale. If he has glucose numbers over 300, either he is newly diagnosed and in denial about the seriousness of this disease, or someone has convinced him to manage his diabetes with insulin and he hasn’t a clue about the dietary changes he needs to make. I was on insulin briefly, but I wound up with bg numbers in the 40s, and faced passing out. Finally, the endocrinologist put me on metformin, only.
            i don’t think Ive ever had numbers in the 300s–because I am pretty careful about what I eat. I have pretty much been off sugars, grains, and processed foods, even before I was diagnosed with diabetes. My diagnosis followed a period of severe stress (job harassment). And stress is significant for diabetics and anyone living with a chronic disease. As for your step brother, if he is on insulin, that may be a complication, be cause he is going to have to commit to the necessary diet changes, and then wean off the insulin. Also, people get attached to the bad food they are eating. And no one likes to make changes away from their familiar things. I am sure IF is the way to reverse Type 2 diabetes, but it does require some commitment and determination to get well. Search Mercola.com for some basic articles on EF. I find the “window” method easiest, rather than fasting whole days at a time. Just define the hours you are going to eat, and then don’t eat the rest of the time. Dr. Jason Fung says it doesn’t matter, any mode of fasting will work. But, the foods eaten when you do eat have to be the highest quality- no processed foods, sugars or grains. And, thanks for caring about this guy. I hope he decides to do what it takes to get healthy.

            • Hey Gloria, I spoke with my step-brother about his situation. He is not taking insulin but is on metformin. He is on a low carb diet. He is also kind of on a non-regimented fasting regimen. I believe he has been doing for 1 to 2 months. His fasting glucose is now 370+. If he is truly doing what he says, should he be having better results than this? He has lost about 35lbs, he’s a big guy. I would say hes 240lbs. He is also 76 years old.

              • Dale. I am 75, and one thing Im learning is there is life after 70. I mean 70+ year olds can and do have a right to be healthy! I have also found that fasting seems to trigger high morning glucose levels–for me its in the 160s to 180s even though I haven’t eaten since 4 pm the previous day. Dr. Jason Fung recently spoke about this (Q&A with Brian Mowl). He says its just that we have a large sugar reserve, and the solution is to just keep eating right –off processed foods, eating mostly fruits and vegetables, and fasting, until the reserve is depleted. Metformin is a good strategy–at least according to Life Extension Magazine. It not only keeps insulin levels low and regulates insulin resistance, but it also is antagonistic to cancer. And for diabetics–with all the excess sugar we have–cancer is an ever present danger. http://www.lifeextension.com//Magazine/2012/2/Magnesium-L-Threonate-UC-II-Metformin-Green-Coffee-Bean-Extract-and-Postprandial-Glucose-Levels/Page-03. I would say he is on the right track. And he is so lucky to have your support.

                • Hi Gloria, I recently started experimenting with intermittent fasting by leaving at least a 12 hour gap between eating dinner and breakfast and sometimes I don’t feel like eating breakfast, so skip that too. I’ve been tracking blood sugar levels as I do this and find that the longer I fast, the higher my fasting BG. I’ve been tracking this for several weeks and my fasting glucose is at an all time high now well over 100. I know this might not seem like a very high level, though it is the trend that worries me. I’m hoping that these rising levels are simply the liver releasing excess stored sugars and that eventually I’ll be able to see the trend reverse? I feel fine when I do IF, though I do have a history of adrenal fatigue and only weaned final doses of oral hydrocortisone 2 months ago. There was no way I could fast in any capacity while I was taking HC. Since weaning, It has felt so liberating being able to go so many hours without eating. I just question the efficacy in light of Chris’ article above.

          • Dale, I am so glad I found your post about IF! I have been trying to do that now for about 3 weeks and was wondering how long it takes for it to work.

            • Anita. How long it takes, depends on how you do it. Frankly once I started intermittent fasting, I felt so much better I never want to go back. I have been following it now for about 2 years. If you fast one day a week, you will not do as well as fasting 8 to 12 hours every day. Also, Dr. Mercola is now recommending to eat just 2 meals a day rather than 3 or more within the fasting framework. I would agree with that if you have metabolic problems like diabetes. Since eating a meal is problematic–why do it more often? I would say you should see better blood sugar readings after about 6 weeks. But fasting has many other advantages besides better glucose control–it is now being recommended as a longevity strategy.

            • Anita, its been 6wks with IF. My fasting morning glucose numbers have been fluctuating. I reported early on that I got down to 74 but subsequent numbers have been 83, 96 and 93. I think to reduce my numbers I would need to change my diet, more. I eat a fair amount of fruit during the day. I am not going to do anything until I can get out of the effects of hormone therapy. My testosterone is 0, which in itself can effect blood chemistry. So, I will see where I stand in a few more months. I plan to stay with IF during the wait. Good luck

              • Dale. Those numbers for fasting glucose look great to me–but then I am a diabetic. Im still trying to get mine under 100. However, your A1c score is probably a better indicator of how you are doing. Mine is 5.5, after intermittent fasting about 2 years. keep up the good work.

    • Hello, I have started with IF ( twice per week for 24 hours ) in order to loose weight. I combined it with 4-5 days per week of weight lifting and steady state cardio ( below 75% of Max ) . To my surprise not much happened. I started paleo diet ( 4 weeks ) and still not much happened. Then a friend suggested I extend the IF to 36 hours from 24 hours. To my pleasent surprise I started loosing about 2 lbs a week . So far lost 30 lbs and 7% body fat ( which slightly concerns me because it implies I also lost muscle ). Recently I decided to increase my protein intake to about 1 gram per pound of body weight and started taking BCAA before my fasted workouts. Hope that helps

    • Lins, I would start by simply reducing (half ?) the long acting insulin on my own to see if any effects.
      There are different hormone therapies. Make sure your doc is not giving your “hormone replacement therapy”, patented synthetic hormones, but instead bio-identical hormones. The latter are natural, lower cost, not patented. GABA can help jitters in an hour or so. I take a teaspoon of resistant starch in some lukewarm water and unrefined gray sea salt also when I fast as it has no effect on blood sugars but I believe it is great prebiotics.

  18. I’ve always wondered about this topic.
    I’ve tried IF in the past and maintained it for a long time. I was mainly doing the bullet proof diet which consists of high fat and protein diet, very low carbs. First I lost some weight then I stalled. During that whole IF daily, I was ready to faint. Right now I weigh about 125lb and it fluctuates. My last meal was last night 7pm and today I haven’t eaten since 5. Usually if was doing the IF correctly I would start eating at around 3:30. But around 12pm I was ready to faint. So generally if I don’t eat anything for breakfast I get tired, dizzy, spinning head. I’m prone to low blood sugar. But if I have let’s say a normal ice cream I kinda get little excited lol.
    Any advice would be appreciated.
    Oh my current diet is fair amount of carb, (I train Brazilian jiu-jitsu almost 5 days a week twice a day) and grass fed fat.
    Thank you!

    • Kads. I would suggest looking at A. Christianson’s Adrenal Reset Diet and then incorporate those principles into IF – eating within a restricted window each day. When you go with out eating you bring cortisol into play. You can’t eat ice cream (not normal) on an IF diet. it is essential to eat very high quality food, because you are trying to reset your system here. If you trigger insulin, you are going to get low blood sugar. And. As Christianson suggests, you may need to eat more carbs (good quality) with fiber at the last meal. Good luck. Sounds like you need to make a few adjustments to make it work for you.

  19. Thanks for all the amazing info. Hope I am not missing something with this question…

    My fasting glucose is 85. (is this a normal, high or low number?)

    2 hours after I eat my BG goes to 110+ and I get incredibly tired and foggy headed. The only way to remove the symptoms is to take a 20 minute nap. (is 110 a normal, high or low number?)

    My #1 goal is to stop these spikes and fatigue episodes.

    I never eat breakfast, just bulletproof coffee, then eat a paleo lunch and dinner (high protein and fat, low carb).

    I drink alcohol often…

    Carb cravings every day at 3PM.

    Would you describe my condition as insulin resistance, reactive hypoglycemia or a cortisol problem?

    I am generally happy but don’t get enough sleep. Stress levels are fine.

    Thanks for any info.

    • Jesse. Fasting glucose of 85 is a good number, and a post prandial (after meal) blood glucose of 110 is also a good number.
      As for the fatigue you might want to check out Alan Christainson’s Adrenal Reset Diet. he recommends a high protein breakfast (can be a shake), a green leafy lunch with protein, and a relatively high carbohydrate dinner (no junk) for optimum adrenal function and energy. He also has information on resetting circadian rhythms. That should fix your fatigue and energy issues. Lean about healthy carbs–fruits and vegetables and incorporate them into your diet. Alcohol–I would cut back and aim for one or less per day, Alcohol can really mess up your energy, not to mention mess with your liver and your head! Aim for 7 to 8 hours continuous sleep. Sleeping is for regeneration and repair. It should be high priority.

    • Jesse,

      Those are great numbers and don’t suggest any blood sugar issues. If you’re concerned, try eating a highly carby meal of around 50-60 carbs from starches and fruit. Test your blood sugar at 1, 2, and 3 hours. If your readings are no higher than 130 at 1 hour and then begin to drop back down, you’re likely just fine and don’t need to worry about your blood sugar. The fatigue might be from some adrenal issues (as Gloria already said) and I second her opinion about alcohol. A nightly glass of wine or whatever might be completely fine for you, but I would be cautious about anything more than that – and I would certainly take out all alcohol for at least 30 days and see if that helps.