More Practical Fasting Tips – part 13

posted in: Fasting, Health and Nutrition | 48

A continuation of practical fasting tips. See Practical Fasting Tips.

Will fasting make me tired?

In our experience at the Intensive Dietary Management Clinic, the opposite is true. Many people find that they have more energy during a fast—probably due to increased adrenalin. Basal metabolism does not fall during fasting but rises instead. You’ll find you can perform all the normal activities of daily living. Persistent fatigue is not a normal part of fasting. If you experience excessive fatigue, you should stop fasting immediately and seek medical advice.

Will fasting make me confused or forgetful?confused

No. You should not experience any decrease in memory or concentration. The ancient Greeks believed that fasting significantly improved cognitive abilities, helping the great thinkers attain more clarity and mental acuity. Over the long term, fasting may actually help improve memory. One theory is that fasting activates a form of cellular cleansing called autophagy that may help prevent age-associated memory loss.

I get dizzy when I fast. What can I do?dizzy

Most likely, you’re becoming dehydrated. Preventing this requires both salt and water. Be sure to drink plenty of fluids. However, the low-salt intake on fasting days may cause some dizziness. Extra sea salt in broth or mineral water often helps alleviate the dizziness.

Another possibility is that your blood pressure is too low—particularly if you’re taking medications for hypertension. Speak to your physician about adjusting your medications.

I get headaches when I fast. What can I do?headache

As above, try increasing your salt intake. Headaches are quite common the first few times you try a fast. It is believed that they’re caused by the transition from a relatively high-salt diet to very low salt intake on fasting days. Headaches are usually temporary, and as you become accustomed to fasting, this problem often resolves itself. In the meantime, take some extra salt in the form of broth or mineral water.

My stomach is always growling. What can I do?

Try drinking some mineral water.

Since I’ve started fasting, I experience constipation. What can I do?Constipation

Increasing your intake of fiber, fruits and vegetables during the non-fasting period may help with constipation. Metamucil can also be taken to increase fiber and stool bulk. If this problem continues, ask your doctor to consider prescribing a laxative.

I get heartburn. What can I do?

Avoid taking large meals. You may find you have a tendency to overeat once you finish a fast, but try to just eat normally. Breaking a fast is best done slowly. Avoid lying down immediately after a meal and try to stay in an upright position for at least one-half hour after meals. Placing wooden blocks under the head of your bed to raise it may help with night-time symptoms. If none of these options work for you, consult your physician.

I take medications with food. What can I do during fasting?

There are certain medications that may cause problems on an empty stomach. Aspirin can cause stomach upset or even ulcers. Iron supplements may cause nausea and vomiting. Metformin, used for diabetes, may cause nausea or diarrhea. Please discuss whether or not these medications need to be continued with your physician. Also, you can try taking your medications with a small serving of leafy greens.

Blood pressure can sometimes become low during a fast. If you take blood-pressure medications, you may find your blood pressure becomes too low, which can cause light-headedness. Consult with your physician about adjusting your medications.

I get muscle cramps. What can I do?

Low magnesium levels, particularly common in diabetics, may cause muscle cramps. You may take an over-the-counter magnesium supplement. You may also soak in Epsom salts, which are magnesium salts. Add a cup to a warm bath and soak in it for half and hour. The magnesium will absorb through your skin.

What if I have diabetes?

Special care must be taken if you are diabetic or are taking diabetic medications. (Certain diabetic medications, such as metformin, are used for other conditions such as polycystic ovarian syndrome.) Monitor your blood sugars closely and adjust your medications accordingly. Close medical follow-up by your physician is mandatory. If you cannot be followed closely, do not fast.

Fasting reduces blood sugars. If you are taking diabetic medications, or especially insulin, your blood sugars may become extremely low, which can be a life-threatening situation. You must take some sugar or juice to bring your sugars back to normal, even if it means you must stop your fast for that day. Close monitoring of your blood sugars is mandatory.

Low blood sugar is expected during fasting, so your dose of diabetic medication or insulin may need to be reduced. If you have repeated low blood sugars it means that you are over-medicated, not that the fasting process is not working. In the Intensive Dietary Management Program, we often reduce medications before starting a fast in anticipation of lower blood sugars. Since the blood sugar response is unpredictable, close monitoring with a physician is essential.

Monitoring

Close monitoring is essential for all patients, but especially, for diabetics. You should also monitor your blood pressure regularly, preferably weekly. Be sure to discuss routine blood work, including electrolyte measurement, with your physician. Should you feel unwell for any reason, stop your fast immediately and seek medical advice. In addition, diabetics should monitor their blood sugars a minimum of twice daily and recorded.

In particular, persistent nausea, vomiting, dizziness, fatigue, high or low blood sugars or lethargy are not normal with intermittent or continuous fasting. Hunger and constipation are normal symptoms and can be managed.

Top 8 Intermittent Fasting tipsDon't Tell

1.     Drink water: Start each morning with a full eight-ounce glass of water.
2.     Stay busy: It’ll keep your mind off food. It often helps to choose a busy day at work for a fast day.
3.     Drink coffee: Coffee is a mild appetite suppressant. Green tea, black tea, and bone broth may also help.
4.     Ride the waves: Hunger comes in wave; it is not continuous. When it hits, slowly drink a glass of water or a hot cup of coffee. Often by the time you’ve finished, your hunger will have passed.
5.     Don’t tell anybody you are fasting: Most people will try to discourage you, as they do not understand the benefits. A close-knit support group is often beneficial, but telling everybody you know is not a good idea.
6.    Give yourself one month: It takes time for your body to get used to fasting. The first few times you fast may be difficult, so be prepared. Don’t be discouraged. It will get easier.
7.     Follow a nutritious diet on non-fast days: Intermittent fasting is not an excuse to eat whatever you like. During non-fasting days, stick to a nutritious diet low in sugars and refined carbohydrates.
8.     Don’t’ binge: After fasting, pretend it never happened. Eat normally, as if you had never fasted.

The last and most important tip is to fit fasting into your own life! Do not limit yourself socially because you’re fasting. Arrange your fasting schedule so that it fits in with your lifestyle. There will be times during which it’s impossible to fast: vacation, holidays, weddings. Do not try to force fasting into these celebrations. These occasions are times to relax and enjoy. Afterwards, however, you can simply increase your fasting to compensate. Or just resume your regular fasting schedule. Adjust your fasting schedule to what makes sense for your lifestyle.

What to expect

The amount of weight lost varies tremendously from person to person. The longer that you have struggled with obesity, the more difficult you’ll find it to lose weight. Certain medications may make it hard to lose weight. You must simply persist and be patient.

You’ll probably eventually experience a weight-loss plateau. Changing either your fasting or dietary regimen, or both, may help. Some patients increase fasting from twenty-four-hour periods to thirty-six-hour periods, or try a forty-eight-hour fast. Some may try eating only once a day, every day. Others may try a continuous fast for an entire week. Changing the fasting protocol is often what’s required to break through a plateau.

Fasting is no different than any other skill in life. Practice and support are essential to performing it well. Although it has been a part of human culture forever, many people in North America have never fasted in their lives. Therefore, fasting has been feared and rejected by mainstream nutritional authorities as difficult and dangerous. The truth, in fact, is radically different.

Start with Fasting Part 1

Continue here for Fasting Part 14 

48 Responses

  1. Dr. Fung, as usually when finishing a fast I experience diarrhea in some grade. Any practical tip to avoid this?

    • TJ the Grouch

      Same here, quite annoying. I took care of it by drinking a couple of teaspoonfuls of psyllium seed powder in water once or twice during the fast. Make sure that the stuff is well dissolved in water before you drink it, otherwise it will stick in your esophagus (not a pleasant experience).

      • here too, I am thinking the fasting may have partly to do with detoxing our body.. best to get it all out don’t you think…

      • Interesting. If I have a long fast (a few days at least), when I restart eating, I have diarrhea. I’ve tried different things (starting with smaller meals to break the fast), but haven’t tried any fiber during the fast. It does seem that after a few days of just water (or coffee or broth), there’s nothing in you but water. That water has to come out somehow.

      • I had the same issue after a fast. Does anyone have any more recommendations to deal with diarrhea? Or is this typical?

  2. This was VERY helpful and answered many of my questions. THANKS!

  3. I have adjusted to five consecutive days once a month with bone broth an egg and seaweed soup. Works for me

    I also take small doses of ketone salts. Helps ensure blood sugars quickly go to and stay in the 55 to 65 mg dl range and ketones in the 3 plus MM range
    Have you had patients use ketone salts? (Keto force) I am hoping the ketone esters will soon be commercially available at a reasonable price

    I only use the ketone salts just before and during my five day fast.

    • [email protected]

      Eric I have never heard of Ketone salt I live in Canada do you buy yours in Canada appreciate your expected answer

  4. Bernard P.

    Dr. Fung, what is the cause of the eventual weight-loss plateau? I understand that with alternate-day fasting, gluconeogenesis sets in after about 12 hours, which should have a continued effect on weight loss. What happens to negate this? Does the body gradually gets used to fasting, so that the onset of gluconeogenesis is delayed? Does this mean that basal metabolic rate is eventually lowered by alternate-day fasting?

    • Hi Bernard, i think it is because the body needs to readjust to the new weight before it is comfortable enough to lose more. If you start losing weight quickly (as most people do when finding a diet they can stick to) the brain will eventually signal to the body that there might be a virus/disease in the body so it needs to resist harder in losing the weight. After some time at the new lower weight when the body feels confident that it does get the nutrients it needs to function, it will start releasing the fat stores again. At least thats my understanding of it.

      • Bernard P.

        It makes sense, but what happens when/if gluconeogenesis sets in? Fat *has* to be burned. As I understand it, your explanation, like reduced calorie diets, implies that there is a reduction in basal metabolic rate.

        However, alternate day fasting is not supposed to lead to a reduction in BMR. That’s why it works so well to reduce weight. Thus the mention of a weight loss plateau by Dr. Fung has me puzzled…

  5. [email protected]

    Today is day 7 of my first 7 day fast. Can’t believe I made it!! I have been doing 42 hour fasts for a couple of months with slight results and Megan suggested I try a 7 day fast. I stopped taking my metformin on day 2 because my blood sugars were averaging 88. Fasting glucose upon rising has been low 90’s. I have lost about 10 pounds and my blood sugar readings are fantastic.

    During this fast I had MORE energy than usual and my thinking was clear and sharp. Here is how it went:

    Day 1: hungry and thinking about food all day
    Day 2: not so hungry but had a pounding headache – added plenty of salt to my bone broth
    Day 3: not hungry, lingering headache
    Day 4: feel like a million bucks! No hunger, feel energetic, positive attitude
    Day 5: same as Day 4
    Day 6: same as day 4
    Day 7: feel great and am looking forward to a special meal tonight at my favorite restaurant!

    • Can you let us know your FBS when you refereed?
      Mine goes up for about twice the time of the fast. Five day fast results inten day reseed elevated fbs. Since he white blood cells and stem cells are in a grown mode this seems to be the consequence of the fast and refeeding process.
      Eric

      • [email protected]

        Eric, I don’t understand what you said..

        • Cassandra

          I think he means fasting blood sugar after you start eating again.

  6. Danajo, I am glad to hear someone else is having good results and finding fasting easy. I am on day 6 and feel about like you do minus the headaches. I have however been sleeping in and that is something I never do. I am surprised how easy this has been but I am looking forward to eating again. Will most likely fast again in 5 days. Energy and sharpness of thought and weight loss, not to mention low BG readings are a big reward.

  7. I’m a type-2 diabetic on a LCHF diet taking 2,000mg of Metformin SA each day. I have no problems taking this on an empty stomach; my stomach and diarrhea problems comes when I eat either just before or after I take the Metformin. My questions is, “why does my blood sugar rise while I’m fasting instead of decrease?” I only drink water and black coffee while fasting. I’m also morbidly obese, but I’ve lost about 50-pounds so far.

    • I am on LCHF diet too but I don’t take Metformin on Fasting days. I was under the impression that Metformin stops the liver from dumping Glucose into Blood stream and that was the Goal of LCHF and Fasting to empty Glucose store of the liver so body can start burning fat.
      Do you have any side effect of taking Metformin on fasting day? Do you take it with anything or on empty stomach? How is you BG Levels on Metformin on fasting day?

  8. Dr. Fung, I fast two days a week eating 500 calories on each. How many 500 calories fast days would it take to get the benefits of a zero calories day?

  9. Dr.Fung , I have been looking for info on caffeine. I can’t seem to find any here.. i love iced tea and drink at least a gallon a day… with nothing else besides water. I have been fasting and LCHF for 4 weeks and am losing slowly but losing inches as well..I am just starting out so have a ways to go yet but….. I was wondering could the caffeine cause my insulin to rise? Do you have any articles or webinars on the effects of too much caffeine?

    • Sandy I’m on a LCHF diet too. Just thought that I’d let you know that store bought iced tea contains a ton of sugar should be avoided when on this diet, but if it’s your own homemade version using xylitol or stevia then it’s perfectly fine 🙂

  10. Excellent tips. I sent this to a friend who experienced dizziness when fasting. Hopefully it will help her.

  11. Cassandra

    Heartburn came for me on day 5-6 and 7 of a 7-day fast. Mineral water helped a little. Need some more advice to deal with it when fasting. It went totally away upn breaking the fast.

  12. Cassandra, like you, I get terrible heartburn when on a long fast of several days. I was told to take ranitidine and it does help.

    • Cassandra

      Thanks so much, Pat. Is that over the counter? Will try to get some. Beastly sensation.

  13. Does this make sense?

    I lost half a stone, about one week of fasting, it couldn’t have been water, as I’ve been ketosis for ages, but weighed myself today and the half stone seems to be back.

    This is the schedule I used, it’s only been two weeks though. Eat on: Monday, Wednesday,Thursday, Friday PM. Easily enough, especially when it seemed to be losing weight.

    The second Saturday though, I ate on the PM, but flexible is the name of the game.

    So in summary I was two stone down last Thursday, today it was back. Pretty sure I was not over eating when I did eat neither. Perhaps, it’s water and food?

  14. I am what has been referred to as Type 1 1/2. It was a slow gradual onset at around 25 (now 49). Never had weight issue but progressed into insulin around age 30. I recently have been taking 32U Lantus at night and 12-14U Novolog before meals but have had quite a bit of hypo with that method esp when working out and exercise more.

    I recently started The Wheat Belly diet 3 weeks ago and Dr. prescribed Metformin and Glyburide, then came across this site and thought I would try the Fasting. I am 48 hours into it but morning blood sugars have been over 200, still took Metformin today and 6U of Novolog as BS was 250, only dropped to around 230 2 hours later….maybe I’m trying too much too soon with the diet change and do Wheat Belly 4 more weeks before starting a long fast.

  15. I am new here and this is my first post. I have a question about fasting while taking Metformin. My understanding is the purpose of fasting is to force the liver to metabolize its stored fat into sugar (hepatic gluconeogenesis). It is also my understanding that the purpose of Metformin is to suppress hepatic gluconeogenesis. Is it therefore necessary to stop taking Metformin while fasting to allow gluconeogenesis to occur? I am very confused by this.

    • The short answer is, if your blood sugar is too high, then you need to continue taking metformin.

      I believe there are 2 processes at work here.

      1) In shorter term fasting, less insulin is required to metabolize food because there isn’t any. Less insulin in the blood reduces insulin resistance over time, further reducing blood insulin levels.

      High Insulin levels tend to block release of stored fat to be used as energy. Lower insulin levels allow enzymes to break down stored fat which the liver converts to ketones, which are used to replace glucose as the energy source.

      Metformin suppresses hepatic gluconeogenesis, reducing insulin requirements and thereby facilitating release of stored fat to be converted to ketones.

      2) Longer term fasting for several days will deplete your body’s glucose stores. Gluconeogenisis will still occur to some degree, metformin will suppress this to some extent and help your metabolism transfer from carbohydrate based to fat based. (nutritional ketosis)

      Turning stored fat into ketones requires more energy than metabolizing carbohydrates. If you consume fewer calories than your body requires, you will lose weight.

      Dr. Fung, please correct me if am wrong.

      Birgit

      • Thanks for the quick reply Birgit and congratulations on your weight loss and improving condition. I was somehow combining gluconeogenesis and ketogenis. I now think I understand the process a little better; please let me know. When fasting your body uses sugar first (glycolysis); when the sugar is consumed your body creates new glucose (gluconeogenesis) from the protein (muscle) and fatty acids. Gluconeogenesis also promotes the formation of ketones which can be used by the brain and muscles in place of glucose. On a low carb high fat/protein diet, the consumed protein can be used in place of muscle and energy is supplied by the fat so you decrease muscle wasting as seen in a low calorie diet and promote fat burning. You are correct that higher levels of insulin promote storage of fat and block release of that fat from bodily tissues, while in ketosis, fat reserves are easily released and consumed as energy. As far as Metformin, I guess it will impede gluconeogenisis to some degree but ketosis will still take place.
        Thanks again. Let me know if I got it right.

  16. I am 65 years old and was diagnosed with type 2 diabetes 15 years ago. I weighed 300 lbs 5 months ago, and through experimenting with the right mix of macros on a ketogenic diet together with intermittent fasting with the help of Dr Fung’s videos and website, I have managed to lose 35 lbs and I no longer take gliclazide, only metformin. I usually fast from 16 to 20 hours each day. I have also done 24, 36, and 42 hour fasts. 2 weeks ago I completed a 7 day fast. Living in Toronto, I am fortunate to be able to meet Dr. Fung in person. I am looking forward to my first appointment with him in December.

    I am convinced that for me, Intermittent Fasting as described by Dr. Fung is the key to success. It helped increase my insulin sensitivity enough to reduce my blood sugars with less medication and start losing body fat.

    Thank you, Dr. Fung. I look forward to your personalized and detailed medical guidance.

    Birgit

    • I also drink one or two cups of bone broth daily.

    • Birgit,
      Great job! I am also a huge believer in Dr. Fung’s method. I started without consulting my own doctor ( I DO NOT RECOMMEND THIS). when my doctor saw my A1c drop from 9.2 to 6.4 he said what ever you are doing keep doing it!

  17. Discouraged when blood sugar is high in the morning even after fasting the prior day. last meal on Thursday pm was chili. did not take glipizide that night. fast from that point through Saturday pm. Friday had bowl of bone broth, no glipizide , 2 hours after broth blood sugar 94. next morning blood sugar 164! So frustrating!

    Dr. Jason Fung: This is simply the Dawn Phenomenon. This is essentially the sugar you have stored away coming back out into the blood. It is normal and neither good nor bad. It simply means that you still have some work to do before the insulin resistance is gone. You are on the right track, but not there yet.

  18. […] For more tips continue here for Fasting part 13 […]

  19. Leonardo C. Cortez

    I am a diabetic for 28 years now, my kidney is already affected, I am under the peritoneal dialysis for two years now. I am 65 years old and if fasting can cure my diabetes and kidney failure I would surely try. Thank you very much for your help. God Bless you all.

    Dr. Jason Fung: It may help the diabetes, but the damage done to the kidney is likely permanent and not reversible.

  20. Does anyone else have trouble sleeping when fasting? I think my cortisol levels become so elevated I can’t sleep at night. I struggle with willpower when I’m sleep deprived! Any tips?

  21. Most of the days my fasting glucose is 100. This is meassured with a glucose meter for whole blood.
    I think I might be pre-diabetic.
    Thats why I need to fast, but…
    I dont understand.. I have perfect weight. I am not even mildly overweight, my BMI is 19…
    Could someone so slender like me have to do with diabetes!
    What happens with thin people when they fast? What happens with their weight and shape?

    Dr. Jason Fung: It’s possible, but you need to make sure you are not latent onset type 1. I don’t recommend fasting for anybody under a BMI of 20 due to concerns of malnutrition.

  22. I have a question regarding eating after a long-term fast (7-14 days, normally). I eat a LCHF diet. I’m planning on eating without carb restriction for Thanksgiving and am wondering if there is any preparation I should consider taking in the days leading up to that. Is it ok to eat such a large meal after such a long fast?

  23. I am new to fasting and heard you on Vinnie Tortorich’s podcast.

    A little background. I’m about 6′ @ 385lbs. Blood sugars have been in the 100-110 range first thing before breakfast. Other labs are borderline. Started reducing my sugar and grains recently, and today I completed my first 24 hour fast. I think this is something I can stick with. Just knowing that going without food for that long is making me very curious about how long I could go, given the large fat bank I carry with me.

    I started using the app My Fitness Pal, and what does it say at the bottom of the screen when I log my 800 calorie dinner? -You should eat more calories, your body is going to go into starvation mode.- Not what I expected to see after reading about fasting on this blog. Oh well.

  24. hello,

    I guess I have a silly question:) You say “fruits and vegetables during the non-fasting period may help with constipation”
    So, does it mean we can eat whenever we like after the first meal to the second one?
    I have been doing 18/6 for 3 weeks with low carb ( Net less than 25 gr./day) and feeling perfect.
    However, when I break my fast, I feel hungry, yes, but I cannot eat even one plate of food. My appetite getting lower lately. So, can I feed myself let’s say 2 hour after my first meal?
    Also, I experience some pain on lower abdomen after eating my meals? What can be the reason?
    Thanks in advance,
    Annie

  25. What do you suggest when people experience sharp increases in blood pressure when fasting? This is what has happened to me, on more than one occasion. My BP is fairly well controlled with 25 mg daily of HCTZ. When I fast, after about the 20 hour mark, my BP goes up to 170/100, and it can take a day or so to come back down. I’m not alone in this. There’s a lengthy thread about it on a forum for the 5:2 fasting plan.

    At the moment, until I can gain some understanding of this effect and what to do about it, I’ve had to discontinue fasting. Ironically, my hope had been that eventually I’d be able to be weaned off the HCTZ by practicing fasting. I’d still like to be able to do this, but I don’t see how it’s going to work.

  26. Marcelo Poletto

    Can I do more than twice a week? 24h fasting, eating 1x per day. Thanks.

  27. MOST lean people will feel very weak and tired on fasts beyond 36 hours or so. That feeling isn’t true weakness. You can still do the same calisthenics or yoga you would normally do, and any exercise that is heavily dependent on bodyweight, such as pull-ups or handstands, will be easier due to the big drop in weight as glycogen stores are depleted. You can also do endurance exercises that can be done burning mostly fat, as well as when not fasting or maybe better. But your body will probably be sending constant signals to lie down and rest.

    I don’t know why the doctor says otherwise. I think he is talking about shorter fasts or working with people who are overweight. With lean people, the body goes into conservation mode quickly, though this can be overridden by the mind if there is a good reason, such as you don’t want to get out of shape by skipping daily exercises or you have to go to work. If there is no good reason to override the feeling of weakness, listen to your body and just lie down and rest.

  28. Doctor, I noticed you mentioned that coffee is a good tool for negating hunger, however you also state that cortisol releases sugars into the blood stream increasing insulin. Coffee/Caffeine increases cortisol so should we be drinking it to begin with?

  29. Samantha Vanesler

    Dear Dr. Fung,
    I’m 36 years old and Type 2 diabetic with a recent A1C of 10.2. I also have PCOS and hypothyroidism. I have been prescribed 2000mg of metformin daily and 15 units of Toujeo insulin nightly and and a 1 shot weekly of trulicity. I also take .75 of levothyroxine daily. I’ve recently been to an endocrinologist who has prescribed all this for me and of course to eat 5-6 small meals daily. I feel that everything you are saying is amazingly truthful but of course is against everything I’m told by my physician. I really want to start this regimen and life change but how do I find a doctor in my area that will allow this and to monitor me following your plan? I feel that it will be too dangerous to do this on my own.
    Sincerely,
    Samantha

  30. Dear Dr. Fung,
    Is it normal to experience sudden onset diarrhea an hour or two after breaking a fast? If yes, will this go away after repeated fastings? If no, what can I do to prevent it?

    Thanks!
    Lisa

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