Intermittent fasting, or IF, is a type of diet that allows you to eat normally five or more days each week and avoid eating for 16-18 hours each day. The typical intermittent fasting schedule involves skipping breakfast and consuming a very small dinner, which may be as little as 500-600 calories. Those who practice IF have reported significant improvements in blood pressure, cholesterol, insulin resistance, arthritis, brain function, and weight.

Intermittent Fasting (IF) is a weight loss technique that involves restricting caloric intake for a period of time every day, preferably between 12 and 16 hours, and then eating normally for the rest of the day. The goal is to consume fewer calories than average over a 24 hour period. Intermittent Fasting is thought to be effective in reducing body weight, body mass index, blood glucose levels, and cholesterol levels. However, the long-term effect of Intermittent Fasting on the human body remains unknown. Some studies show that Intermittent Fasting can cause an increase in body weight.

Intermittent fasting is a diet protocol where an individual fasts between the hours of 8pm and 12pm each day. The idea is that this fasting window will allow the body to metabolize its food more efficiently than normal, resulting in weight loss and improved health.. Read more about best intermittent fasting for weight loss and let us know what you think.

Who is a candidate for intermittent fasting?

Is it possible for youngsters who need to reduce weight to fast?

For children, fasting is not an option. My suggestion is to keep additional sugars and sweets to a minimum. Fasting may be reduced to two meals each day, but not for extended periods of time.

My 31-year-old daughter, who maintains a healthy weight, engages in physical activity (rowing) four times a week. She wants to know whether she can fast or if it’s not a good idea for athletes.

Fasting training is not only safe, but it also offers a number of potential advantages that many top athletes experience. Yes, it comes highly recommended.

Is it permissible for women to fast throughout pregnancy and after delivery while breastfeeding?

I do not recommend fasting while pregnant or breastfeeding. Short-term fasting (<24 hours) may be acceptable to some, but certainly not long-term. There is the fear of nutrient deficiencies, which I think far outweighs the potential benefits.

How to optimize muscle development and fat burning by combining intermittent fasting with resistance exercise.

Is there a difference in intermittent fasting on training days vs non-training days? Is it good to use BCAA supplements when fasting – or on fasting days – to avoid muscle mass loss?

There are many timetables to choose from. Most individuals fast for 24 hours before working out, which is known as a fasting exercise. With high amounts of growth hormone, you should be able to recuperate and develop muscle more quickly.

Because the loss of muscle mass after a brief period of fasting is modest, BCAAs are not required, although bodybuilders often take them. The drug’s efficacy is unclear, and the data available is mainly anecdotal. Many athletes stick to a routine that includes fasting for 24 hours, exercising, and then breaking the fast with a high-protein meal.

Is intermittent fasting suitable for adolescents?

That’s not the case. Short fasts (less than 24 hours) are permissible on occasion, while lengthy fasts are not. Children in most faiths do not fast since their bodies need more nutrition to develop.

Is it always a good idea to fast while attempting to conceive? Should intermittent fasting or no fasting be employed instead?

You are welcome to test it, but we do not have sufficient data. Fasting, on the other hand, should not be done when pregnant.


Various options for intermittent fasting

Is there a substantial difference in the advantages of fasting for 24 hours vs. fasting for several days vs. fasting for 16:8?

The major difference, as you would expect, is that shorter fasting durations are less effective and are thus done more often. The 16:8 fast, for example, is often observed on a daily basis, whereas the 24-hour fast is observed 2-3 times each week. I usually recommend longer fasting times for more severe insulin resistance and shorter fasting periods for maintenance.

Fasting all day with a 4-5 hour respite in the evening is the fasting regimen that most suits my lifestyle. This is something I feel like I could do every day of the week. Is this something you should do? How many days a week does the FP have a good week?

Daily fasting of fewer than 24 hours (20 hours fasting, 4 hours eating) or warrior style fasting is possible. The word “healthy” is always relative to your objectives. You may fast as much as you want if you’re simply trying to lose weight. The harmful health consequences of consuming just 4 hours each day are unknown.

I was able to complete 18 hours, 24 hours, and three days without difficulty, and I adjusted my schedule during the week based on how I felt and whether or not I had social commitments. Is it preferable to keep to a 24-hour fasting plan for consistency, or is it better to alter fasting schedules on a frequent basis?

I’m not aware of any good statistics on this, but I believe it is preferable to alter the environment so that the body does not have time to adjust. This inconsistency, on the other hand, may lead to individuals not fasting at all, which is equally harmful.

As a result, it is entirely dependent on your own preference. If you want a regular schedule for the purpose of bonding, go ahead and do it. However, I’ve discovered that a continuous change of atmosphere is the most beneficial to my health.

My husband is very overweight; he weighs 164 kg and is 179 cm tall. His fasting blood sugar is acceptable, ranging between 4.8 and 5.6 mmol/l; nevertheless, his insulin levels are extremely high; the initial test revealed 32.2 IU/ml….. I understand that keeping insulin levels low is critical for weight loss, but what is the best course of action? 16:8 MF every day or a 24-hour fast twice a week? What would you suggest?

Both types of fasting are allowed. It all comes down to personal preference and which produces the greatest results. Both systems are used by us. Fasting for 24 hours 2-3 times a week is more powerful than a 16:8 diet in my opinion, however you should do what works best for you.

I have a question regarding individuals who work late at night. Can you provide me an example of a decent daily fasting program? I’m considering a feeding window of 2pm to 2pm (2-3 meals and then fasting at night); clearly, this isn’t feasible for everyone.

I’m also intrigued by the eating window. Isn’t eating from 10 a.m. to 6 p.m. equivalent to eating from 1 p.m. to 9 p.m. if I sleep from 10 p.m. to 2 a.m.? Isn’t it preferable to eat earlier in the day in order to burn more calories, or is it just another urban legend that evening meals cause weight gain?

Sleep deprivation and an abnormal circadian rhythm are common issues for those who work at night. Cortisol levels may rise as a result, making weight loss more difficult. This is not the same as the insulin line, which is used by the majority of individuals.

The time of day you eat is likely to have a role, but only in a minor way. There is no agreement on when to eat, since some people suggest eating in the morning and others prefer eating in the evening. In terms of lifestyle and weight reduction, I believe it is more essential to test both alternatives and discover which one works best for you.

What motivates individuals to break their fast after a lengthy period of time? I’ve been on the LCHF diet for almost six months, and intermittent fasting (eating very little) has shown extremely sluggish effects. I finally tied the knot last weekend and began a four-day fast, assuring myself that I could have eggs for breakfast every night. I don’t feel hungry when I get up, so I keep fasting (broth, water, coffee with cream and coconut oil). Since October of last year, I’ve dropped approximately 12 kg, and I still have about 20-25 kg to go. I’m feeling fine (albeit after preparing the soup this morning, I was tempted to eat the chicken on the bone), and I’m not sure how long I should keep going. Until I drop ten kilograms? 20 kilograms? I determine whether or not to continue fasting every day, so I don’t want to commit till I’ve lost another 10kg, but having an indication of how long I may be able to go would be fascinating. I’m sure you have folks who have been suffering with this for a long time!

There is no hard and fast rule. It is dependent on your health and objectives. People have taken it for a month, but only under the care of a doctor. Many individuals are fasting for 10 to 2 weeks, but they are all under medical care. Many individuals fast for a week, either on their own or as part of a cleanse.

However, I am unable to provide personalized counsel, and you must make your own decision in consultation with your physician.

I’m terrified of fasting since every time I’ve attempted it, I’ve come down with a cold. How do I start fasting? Should I start with shorter fasts and gradually increase the duration?

There isn’t a link here, in my opinion. Start by skipping breakfast 2-3 times each week and work your way up. Some individuals like to take things slowly, while others want to dive right in. It’s like being in a swimming pool. Some people wade, while others plunge right into the water. It’s all up to you.

I am obliged to fast for 30 days as a Muslim, which began on Thursday, June 18, and I have fasted for three days, averaging 18 to 20 hours each day. Tips on how to get the most out of fasting during this period. Adults should fast two days a week, on Monday and Thursday, even after Ramadan, the month of fasting. It’s basically a rehash of what you stated in your Andreas interview.

Some individuals have a habit of overeating and indulging in food before and after dawn and sunset. I suggest skipping breakfast and eating as normally as possible after sundown. For this reason, several Ramadan studies have indicated weight increase during this time.

I’d want to fast in order to reduce weight (10 pounds or so) and improve my overall health. I attempted the 24-hour fast twice in separate weeks, and both times I was so hungry at supper that I felt full the following day and ate more than normal. Is it natural to have such strong cravings? Is this something that will eventually normalize, and if so, how long will it take? Is it possible that my body is telling me that a 24-hour fast isn’t for me?

Try to eat regularly as much as possible. You’ll eat a bit more than normal at first, but this should fade as you grow accustomed to fasting. This is a very frequent occurrence. Many individuals get stomach discomfort as a result of overeating.



What to Think About When Intermittent Fasting

Is it okay for me to consume bone broth during Lent?

Bone broth is, without a doubt, highly recommended. It’s high in minerals and vitamins, and it’s filling enough to keep you full. Another benefit is that you may use a substantial quantity of sea salt. Other liquids used while fasting, such as water, tea, and coffee, may not contain salt and may cause dehydration. Mild dehydration, for example, may produce cramps and headaches while fasting for an extended period of time.

Bone broth is, thus, strongly suggested (recipe). It’s also paleo in the sense that it’s a highly traditional and long-standing meal.

Is it OK for me to consume coffee with milk during Lent? I’m not a fan of black coffee. With my coffee, I sip milk.

Although milk technically violates the principles of genuine fasting, a little quantity of milk or cream added to coffee helps compliance for some individuals. As a result, we allow milk/cream in the coffee in our program, but no sweeteners or sugar.

Sorry for the dumb question, but how much cream is a little amount:-)))) I hope you’d tell me because if you don’t, I’ll assume 250ml is great, and I don’t mean that 🙂 I’m on my third day of fasting, and I had 40g of whipped heavy cream (33%) in my coffee twice today. Is it excessive?

Yeah, instead of a full can, I was thinking 1 or 2 tablespoons. Cream increases insulin production since it still includes milk protein, defeating the aim of fasting. Please, just fat. B. There will be less coconut oil.

Do you suggest drinking anything except water during the 16-18 hour fast? Is it okay to drink regular black coffee or tea with caffeine, or can caffeine increase blood glucose levels?

All types of tea, coffee, and bone broth are allowed. Even though it’s not legally permitted, I let a little amount of cream or coconut oil in my coffee for consistency. The caffeine amount isn’t a concern for me.

What are your thoughts on xylitol being used to sweeten coffee and tea during fasting? Is it likely that insulin levels will continue to rise?

There is a scarcity of information about sugar alcohols, especially xylitol. As a result, I’m not sure whether they’re appropriate or not. However, if in doubt, I think that they are not traditional or genuine goods and should be avoided.

I’ve fasted a few times. My longest endurance run was a few years ago, and it lasted 14 days. I’m back on the fasting wagon today, on day three, and I’m feeling great. I ride my bike for all of my commute, therefore I have leg cramps. The addition of magnesium and 1 tablespoon of salt to the water is very beneficial, although salt water is unpleasant to the tongue….. So I came upon this cup of soup: Per serving, there are 0.6 grams of fat, 1 grams of carbohydrates, 0.2 grams of protein, and 2.7 grams of sodium….. Is it possible that I’m being too concerned about the 1g of carbs? Is it usual to have one in the morning and one in the evening?

Yes, I wouldn’t be concerned about a little quantity of carbohydrates if you feel better after eating soup.

What do you suggest for constipation, bloating, and a bloated stomach? I’ve discovered that adding fiber to my diet causes stomach bloating.

Fiber is usually our first line of defense, but if that fails, we turn to laxatives like milk of magnesia or senna tea. Constipation is a common problem that may be humiliating. Stool softeners are often used to assist with this issue.

Do you consume your entire daily amount of macros at supper after intermittent fasting finishes (e.g., after 4 p.m. until 8 p.m.)? Can someone, for example, have a 1200 calorie lunch with the usual LCHF ratio of 5% carbohydrate, 20% protein, and 75% fat after 20 hours of intermittent fasting? Should the overall number of calories consumed at supper be reduced? I attempted the 1200 calorie fasting technique and found it to be very difficult! However, if you eat an alternate supper to break the fast, say 600 calories at a 5/20/75 macro ratio in LCHF, you’ll only receive around 25 grams of protein per day, which is negligible if you’re fasting 20/4.

I don’t suggest calorie counting. I attempted to eat as normally as possible after fasting. This will be the same meal as normal, but with a little bigger amount.

Keep in mind that your protein consumption on fasting days will be much lower than usual. Although most individuals consume at least 3-4 times the amount of protein required for optimal health, you may simply compensate by eating a larger dosage on the day of your meal.

Is it preferable to drink two tablespoons of apple cider vinegar (diluted in water) during Lent, or should I wait until one of my meals?

Jason Fung, M.D. : Yes, both are permissible. 2 teaspoons before bedtime decreases blood sugar levels in the morning.

What do you use to substitute salt for individuals with high blood pressure during Lent? Is bone broth with salt still a viable option? Is it necessary for them to be cautious about the amount?

I usually do not suggest a low-salt diet for uncomplicated hypertension, but rather a regular diet. If you consume bone broth, the quantity of salt will still be considerably lower than on a regular diet, thus I wouldn’t worry about it.


During fasting, blood glucose and other tests are performed.

My blood sugar lowers to 65 mg/dL when I just consume chicken soup, and it reduces to 55 mg/dL after five days. Have you seen a comparable drop in your patients who are fasting?

This is a common occurrence during Lent.

Is it a cause for worry if my blood sugar increases to 140 [around 8] when fasting?

This is a very frequent process that occurs during fasting and involves the breakdown of glycogen or the synthesis of new glucose in response to hormonal changes. It isn’t nice or terrible in any way.

Consider it this way: Your body just transfers sugar into your circulation from its storage sites (glycogen and fat). This is where your body will be able to burn it.

Last week, I purchased a glucose and ketone meter. I tested my glucose level, which was 3.6 mmol, and my ketones, which were 1.9 mmol, after 21 hours of fasting on Friday. I’m concerned about my low blood sugar; should I be concerned? On Saturday, I ran 6 kilometers at a brisk speed on the athletics track, and my blood glucose level was 2.4 mmol. I’d want to remain in ketosis, but I’m concerned about the swings in glucose levels. I don’t have any symptoms of hypoglycemia, but when the numbers are off, I feel nervous!

Pay attention to your body. Stop if you don’t feel at ease. Otherwise, if you’re worried, cut the length of your fast in half.


Between-fasting-period dietary guidelines

Greetings, Dr. Fung! I’ve been following your blog and procedures with excellent success since July, and I’ve also written a paper on Marty Kendall’s insulin index. I eagerly anticipate each of your postings.

What are your recommendations for utilizing whey protein powder, and how does it affect insulin levels? Whey protein, as a concentrated dairy product, may decrease insulin, according to Mark Sisson (who sells it), yet we frequently hear that whey protein as a concentrated dairy product increases insulin.

I don’t suggest using dry whey since it’s a highly processed chemical rather than a genuine food. Whey is a powerful insulin stimulator, but it also fills up quickly, so its weight-loss impact is likely to be more neutral.

If I’m on an HFLK or ketogenic diet, should I take a multivitamin?

No, it’s not required if you consume mainly complete, unadulterated, natural foods.

Probiotics and prebiotics seem to be in favor these days for feeding the gut bacteria. Do you have any foods that you suggest for gut microbiota support? Some diets, for example, the B. To support the beneficial bacteria in your stomach, the Perfect Health diet advises eating safe starchy foods like potatoes and rice. Do you prefer rice or potatoes as a side dish? Can you become ill if you don’t eat enough of these healthy carbohydrates, and what about gut health?

I’m sure I’ll ruffle a few feathers by saying this, but I’m dubious of the gut microbiota hypothesis of obesity. As a result, I would not suggest any goods for this reason.

Rice and potatoes, on the other hand, are not required in a healthy diet. Personally, I eat both since I like both on occasion. However, I am not attempting to lose weight. Yes, I would restrict rice and potatoes if it were up to me.

Obesity is induced by insulin rather than carbs. Despite the fact that starch increases insulin levels, there are methods to bring them down. Protective elements such as fiber and vinegar may be added. You may also add natural fats and change your meal pattern (intermittent fasting).

[Ed: While fiber, fat, and even vinegar may delay or decrease the absorption of certain carbs, this does not imply that they entirely avoid glucose and insulin rises. Furthermore, although it may reduce the duration of a blood sugar rise, it can also extend the period that blood sugar remains high. As a result, we do not suggest this method as a safe approach to increase carb intake. If you truly want to eat potatoes and are going to do so in some manner, you should follow the instructions below to make your dinner a bit safer. However, it is still recommended not to adopt a low-carb diet in order to completely enjoy the advantages].

As an extra fat, I use high-fat mayonnaise in my meals. There is no crab in it, no protein, and 11 grams of saturated fat. This amount, however, includes 70 mg of sodium. Is this causing any issues?

Sodium limitation isn’t required unless you have a specific medical problem. Dr. Salim Youssef recently proved this in the New England Journal of Medicine.

Although there is continuing discussion regarding the necessity to reduce sodium, I am not concerned about this restriction for healthy individuals.

I have a couple of concerns regarding alcohol and ketosis/fasting…. 1) I’ve heard that alcohol will put you out of ketosis. Is this to say that when you drink, your body burns the alcohol to get rid of it, and then falls back into ketosis as soon as the alcohol is consumed?

2) During a lengthy day of fasting, on the sixth or seventh day, I made the mistake of drinking a bottle of red wine (or thereabouts). That night, I was in excruciating pain, but in the morning, there were no more issues. Is it safe to consume alcohol after a lengthy fast? Is it true that the body only burns alcohol when it is drunk? (That night, I recall being chilly and hungry…)

When it comes to losing weight or reversing diabetes, I often encourage patients to avoid alcohol for the simple reason that the body can use alcohol as fuel, while we are attempting to persuade the body to burn stored sugar. I’ve also heard rumors that he stopped ketosis for the same reason.

It’s curious that so many low-carb specialists exclusively discuss carbohydrates and blood sugar, yet so little is known about protein’s ability to increase insulin. And that it’s not (only) about blood sugar, but also about how frequently you consume what you eat (unless it’s pure coconut oil or lard :-)…

Yes, I have an insulin-centric perspective on obesity, while most people have a carb-centric view. Carbohydrates constitute a significant part of insulin, but they are not the sole one.

What are your thoughts on the notion that dietary fiber is harmful and may create perforations in the intestine wall? Is it possible to consume too much fiber? What are your thoughts on the impact of diet on our bodies’ acidity/pH balance?

Fiber, in my opinion, is not intrinsically harmful. I really believe it can help prevent insulin rises. Fiber isn’t harmful for the stomach, in my opinion. I’m likewise not convinced by the acid/base hypothesis.

I’m perplexed by certain people’s views on carbohydrates vs. pure carbs, and their assertion that fiber should be taken into account… what is the bottom line on pure vs. non-pure carbs?

The primary issue, in my opinion, is excessive insulin levels. As a result, fiber, which tends to decrease insulin levels, should be avoided, and we believe the idea of pure carbs (carbohydrates without fiber) is sound.

What, if any, limitations do people who follow the LCHF diet have if their gallbladder is removed?

I’m not aware of any.

I’m still experimenting with various fasting and LCHF diet combos. I’m a glutton for food, particularly after a fast. Is it risky to break the fast all at once with a large amount of food? When I first begin eating, I am very hungry, and I quickly overeat. has been wounded and is suffering from diarrhea. Is it possible that alternating between an empty and a full stomach is damaging to the stomach over time?

I don’t believe it is hazardous, but it is certainly unpleasant. As a result, including a modest meal into a fasting diet is generally simpler. Give yourself at least half an hour to digest a handful of almonds and a small salad.


Intermittent fasting and weight reduction

For the last six months, I’ve been on a rigorous LCHF diet and have dropped ten pounds. My weight reduction has stopped, and I am currently 20 to 30 pounds below the optimum weight for my feminine frame (5’11”). I just watched your fasting video and decided to give it a try since nothing else seems to work. I’ve been fasting for almost 72 hours and have dropped just 0.7 pounds! What a source of despair! I don’t have diabetes, I don’t have high blood pressure, and I don’t have an increased fasting blood sugar. My morning ketones were 1.2 mm after the first day of fasting, and 1.5 mm after 48 hours of fasting. I’m at a loss for what to do now, and I’m frustrated. I understand that you are unable to provide precise medical advice, but any general idea or advise you could provide would be much appreciated. Also, please understand that I am not alone in my quest for a healthy weight. I’m not referring to a self-help book…. I’m 157 pounds and just 78 centimeters tall! My abdominal circumference (without retraction of the belly button) is 40!!!!! Please assist us!

Water is frequently to blame for the quick weight loss that occurs while fasting. Water will not help you lose weight if you are following the LCHF diet. After that, the average weight reduction each fasting day is half a pound. So your weight reduction is a little below normal, but not out of the ordinary. If a pound of fat contains 3500 calories and you consume 1800 calories on a daily basis, two full days of fasting will result in a one-pound weight reduction. Because your metabolism is likely to be sluggish, you will only lose 0.2 to 0.3 kg.

You may try altering your program if you aren’t receiving the results you want. Fast on a regular basis. Fast over extended periods of time. Fast for a shorter period of time and more often. There isn’t a better system. Above all, try to figure out what works for you and produces results.

My latest A1C was 5.6 after I started intermittent fasting! But, despite having full control of my diabetes, I still struggle to reduce and maintain my weight (I’m 5’10” and weigh 80 kg). I am 50 years old and have T2 diabetes, and I believe that both of these conditions have a detrimental effect on my ability to reduce weight. Since my blood sugar was under control, I focused on insulin management to determine whether it was the source of my issue. However, after two weeks, I’m still only able to maintain my weight rather than reduce it, which is discouraging.

I have two inquiries:

1) Would include a high-fat source in a protein-rich diet decrease the diet’s insulinogenic effect? Will my insulin response be reduced if I eat a 2.5-gram steak for supper and add a high-fat food like avocado or sour cream instead of simply eating the steak?

2) I know you stated the optimal fast for each individual is the one they can stick to, but would a longer fast be more helpful if someone has severe insulin resistance? And, if that’s the case, do you believe that fasting for a week or more, rather than, say, infrequent 3-day fasting augmented with regular intermittent fasting, would have a substantially greater effect?

1. I’d use avocado or some natural fat to replace part of the protein steak. Protein, unlike fat, may still activate insulin, although to a lower extent.

2. Fasting for longer periods of time is much more effective than fasting for shorter periods of time. Because patients on high dosages of medicine have greater insulin resistance, we typically start with lengthier fasts.

Type 2 diabetes and intermittent fasting

I’m a type 2 diabetic who’s been off all medications for the last eight months and follows an LCHF diet. My blood sugar levels are about 60 degrees when I attempt to fast for a few days, and I’ve been told that this is too low and that I need to eat. Is it natural to feel hungry and vulnerable at the same time? Is it common to have low blood sugar when fasting? In addition, the average ketone level is 2.5 on a daily basis.

If you use blood sugar-raising medicines, you must exercise extreme caution to prevent hypoglycemia. Otherwise, your body should be able to generate fresh glucose while fasting, but hypoglycemia may occur in rare instances.

Sugar levels should be low and ketone bodies should be high during fasting. Ketones are generated as a source of energy for the brain, thus this is a common occurrence.

Does the presence of ketones in the urine in a person with T2 diabetes imply an improvement (reduction) in insulin levels if the ketones are the consequence of a ketogenic diet?

When insulin levels are low, the body produces ketones, which the brain uses as fuel. Some individuals use it to ensure that their diet is carbohydrate-free.

What does an eGFR of 80 ml/min in a type 2 diabetes patient imply, and what can the patient do to avoid renal disease from worsening?

The eGFR of 80 is considered to be close to normal. Diabetic kidney damage can only be prevented by eliminating diabetes. Everything else is simply a reshuffle of the Titanic’s seats.

I heard you talk about a new diabetic medication called Farxiga, SGLT2, at one of your seminars. How might fasting work with just one meal each day?

Fasting works effectively with SGLT2 inhibitors since they eliminate sugar from the body via the urine. We urge the body to burn sugar by fasting. You excrete sugar in your urine as a result of your medication.

However, there are adverse effects, such as urinary tract infections, as with any medication, but generally, I believe it is a wonderful treatment.

I’m a type 2 diabetic who eats a low-carb, high-fat diet and now fast throughout the day. On the way to work, I drink a litre of water with unsalted almonds (about 50g) and 2 or 3 black coffees, and when I come home, I eat supper, which is usually meat or fish with veggies. I eat blueberries and strawberries with double cream if I’m still hungry. I’ve been doing this for a week and a half and have dropped ten pounds. My blood sugar is currently between 6 and 7, and it’s getting lower every day. Is this a common occurrence? What dietary modifications do you suggest for me?

If you’re seeing positive results, this strategy is obviously working for you, and I wouldn’t alter it. In general, I suggest eating an LCHF diet with fasting on occasion. Your approach is unmistakably consistent with this.

Greetings, Dr. Fung. I’ve just lately found you, and you’ve been a complete revelation. You made the sun shine in my life, which had been cloudy. Thank you for everything that you do. I’m waiting to see my doctor (UK – two weeks) to check whether any of the medicines I’m taking for my heart and renal issues have any adverse effects, but I fasted for 39 hours last Tuesday and want to do another one today since I feel fantastic. I took my regular 32 IU Lantus, but not my regular Humalog. I’ve also taken additional medications without consulting anybody. Was it possible that I used too much insulin since my blood sugar after fasting was 3.6? What would you suggest? And, once again, thank you in advance.

I can’t legally advise you on your specific case, but we aim to maintain blood sugar levels between 8 and 10 in our facility. This level is greater than usual since hypoglycemia is considerably more hazardous while fasting.

As a result, we keep a close eye on blood sugar levels when fasting and always advise taking less insulin rather than more. You can always take more if you take too little.

If you consume too much, you’ll need sugar to compensate for the hypoglycemia, which defeats the purpose of fasting.

Which fasting schedule is optimal for diabetics with HbA1c levels over 10%?

There is no better way to heal than to fast. The most intensive settings provide the quickest results, but they aren’t the greatest. Some individuals like driving slowly, while others prefer driving quickly. Short fasting is better for certain individuals, while prolonged fasting is better for others. See my website’s blog series post for additional details.

Dr. Fung, how are you today? I just finished watching your presentation on the most significant factor in obesity. Genius! My inquiry concerns metformin’s mechanism of action. As far as I’m aware, it prevents the liver from producing glucose. So, if it’s beneficial for the liver to convert fat to glucose based on your background, will metformin help avoid hepatic steatosis?

Metformin inhibits the production of gluconeogenesis. So, no, it won’t keep your liver from becoming fat.

Metformin is something I take. This medication gives me significant stomach issues, therefore I can’t take it without eating. During my previous fast, I just stopped taking the medicine for four days and then restarted it once I began solid meals. Is this an acceptable course of action, or am I in danger of causing a problem?

I can only add that because of gastrointestinal problems, we seldom take metformin on an empty stomach in our IDM clinic. As long as blood sugar levels stay within a healthy range, this is acceptable. I’m not sure whether you should do it yourself.

I’m a 48-year-old obese lady on T2, 2000 mg of metformin each day, no insulin or other medications, and otherwise in good condition. I’ve discovered that I can’t generate detectable ketones in my blood without fasting for at least three days (just water, broth, pure tea). Even a 90 percent actinic fat deficit does not result in ketones in the blood (I don’t bother with pee testing). I’m guessing it has something to do with IR.

1. Is it common for someone with a high RI to have to take such drastic steps to get ketone bodies to produce? 2. How long would it take to eradicate or at least substantially improve this level of RI if a lengthy fast (4 days or more) is performed 2-4 times per month and an LCHF diet is followed throughout the fast?

1. Instead of glucose, the body produces ketones to provide energy to the brain. Your body does not need to generate ketones if the glucose supply is enough. Yes, this is typical and most likely due to your IR.

2. There is no such thing as a standard; everything is based on the individual. Some individuals recover from IR in a matter of weeks, while others take up to a year.

I am 67 years old and have had type 2 diabetes for 17 years. In my diabetic study, I learned that those of us who have had diabetes for a long period have a tougher difficulty curing it. Is this true? Is the information provided accurate?

That is, at least, our experience. If you’ve just been diagnosed with T2D, you should expect the condition to pass rapidly. It won’t last a month if you’ve owned it for 17 years, but it will last a couple.

My fasting blood glucose level is typically higher throughout the day since I have type 2 diabetes. Even on a fasting day, it rises by 40 percent or more throughout the night without eating. I attempted to eat something, maybe a boiled egg, which helps to decrease my blood sugar in the morning. Is this enough to change my mind, or do you have another idea? I’ve spoken to other diabetics who are dealing with the same issue and aren’t getting any helpful advise from their doctors. Vinegar, perhaps? Any and all ideas are welcome.

Yes, this is a frequent issue associated with the phenomena of twilight. The body produces a rush of counter-regulatory hormones that push sugar into the circulation just before waking up. This is why, despite not eating, your fasting blood sugar is high.

This indicates your body’s insulin resistance. The basic issue is that your body is releasing too much sugar into the circulation from its reserves. This simply indicates that you have an excess of sugar in your system.

You may either continue your fasting regimen and take more time, or you can shorten it by increasing the length of your fast.

When do you believe a type 2 diet may be considered to have transformed blood glucose levels to what levels?

If you are not on medication and can maintain your A1C below 6%, I believe diabetes is reversible.


The advantages of FI go beyond weight reduction and type 2 diabetes management.

When individuals start eating an LCHF diet, they often experience relief from indigestion. What is the reason behind this? I’m trying to persuade my nephew that LCHF is the best way, but nutrition isn’t his strong suit, therefore I can’t get him to read your site! I’m convinced it’s because of his high-carbohydrate, high-sodium diet that he gets severe heartburn! (He’s also a bit of a hunk!)

There are two major consequences, I believe. To begin, it is critical to prioritize genuine food over highly processed foods in order to maintain healthy GI function. Second, losing weight may help with reflux problems.

– Dr. Fung I’m 70 years old and overweight, but the LCHF diet has helped me lose 30 pounds in approximately 6 months. My blood pressure fell as well, and my doctor had to discontinue my blood pressure medicine since I became dizzy when it did. My blood pressure has finally returned to normal, despite the addition of Ramipril, and my weight loss has halted. My BMI remains at 30. Do you believe IF 16:8 can assist in the resolution of these two issues?

Blood pressure and diet have a weaker relationship than blood sugar. It wouldn’t harm to try the 16:8 IF, in my opinion.

Do you observe a reversal of renal damage in patients that strictly follow FI in your practice? If so, at what stage of renal disease or when the patients reach a particular age? Or if they eat a ketogenic diet even when they aren’t fasting? I’m curious whether there’s any chance for CP improvement once T2 diabetes is eliminated. When I informed my endocrinologist about a research in mice that showed a ketogenic diet completely reversed renal disease, he replied, “But we’re not mice!” Please let me know what you think.

Renal function improvement is uncommon. It happened to around one out of every 300 individuals. Although type 2 diabetes may be restored, renal function cannot. Even after pancreas transplantation for type 1 diabetes, kidney function does not improve for another ten years.

Until I began intermittent fasting, the LCHF diet did not alter my weight and only marginally decreased my type II diabetes. My first viewings were in the 1980s and 1990s. My thyroid is acting up once again. I’ve had hypothyroidism for almost 20 years and rely on synthetic hormones to keep it in check. The dose was not altered throughout this time. My TSH fell to zero, and I became hyperthyroid. The doctor lowered the medicine’s dosage to practically nothing. My fasting blood glucose level, on the other hand, has increased to 130-140. I don’t consume any sugar and just eat low-glycemic veggies with plenty of fat and oil. All of the glucose in my circulation must be released by my liver. Do you have any ideas or experience with this scenario?

I can’t assist you since there isn’t a lot of research on fasting and changing thyroid medications, although I’ve heard of many anecdotal instances where thyroid function improved quickly. All you can do if your blood sugar is too high is stick to your strategy. Of course, it seems like you’re just mobilizing some of the sugar you’ve stored.

I’m curious whether the therapy for type 1 and type 2 diabetes is the same. Is it possible to have a low-carb, high-fat diet?

Yes. When compared to a normal 50 percent carbohydrate diet, both kinds of diabetes improve on the LCHF diet. The causes behind these two kinds, however, are vastly different.


Intermittent fasting and LCHF may have negative consequences.

Is it common for me to experience extreme cold during Lent? Both of your hands and both of your feet… Thank you, especially for the feet at night. I’m hoping this doesn’t mean my RDE (Resting Energy Expenditure) is decreasing.

No, the cold isn’t normal; it indicates that your LER is malfunctioning. On meal days, try to consume a sufficient amount of food.

By missing breakfast, I began intermittent fasting. Today on medXp, I came across the following: According to one research, skipping meals is linked to an increase in belly weight.

So there’s that. I’m fairly sure the research wasn’t done on a low-carb diet. What are your thoughts on the matter?

I would have disregarded it since it was an animal research. The majority of studies that claim to show that you should eat all of the time are false. To lose weight, do you have to eat all the time? No, I don’t believe so.

My doctor is a big supporter of the vegetable oil diet, and he recommends it to all of his patients. For fat loss, I’ve had mixed results with LCHF. Despite my increased muscle development, my weight reduction after four months on a strict, no-cheat LCHF (mild to moderate ketosis) diet has been modest. I’m presently experimenting with 16:8. My doctor advises against fasting since it causes a decrease of protein status, according to him. He wasn’t talking about fasting or anything; he just said that IF has an effect on protein levels in the body. What are your thoughts on this? Proteins are utilized in the same manner as fat reserves are used. If so, can you make up for it by consuming extra protein over the next 8 hours?

Protein loss is low on a 16:8 diet or even after four days of fasting. That is just a myth. On my website, I go through intermittent fasting in great depth, beginning with the first phase.

When your body begins burning protein (muscle) for energy, why would it store energy as fat? No, it doesn’t work that way. That is just a myth.

Are there any side effects of gallbladder fasting, according to your experience? I went on a fat-free diet for 14 days, consuming 500 calories a day, and when I switched back to a low-carb diet, I suffered terrible gallbladder discomfort. Because I am not eating, I am worried that the discomfort may return while fasting because the gallbladder is not functioning (and therefore does not need to make bile). What are your thoughts?

While fasting, we haven’t experienced any issues with gallstones or bile colic. Despite the fact that millions of individuals fast on a daily basis, I have yet to discover a discussion of gallbladder issues linked to fasting.

Except in instances of severe iodine shortage, fasting does not induce hypothyroidism. Hashimoto’s disease is an autoimmune disorder that has nothing to do with one’s diet, whether it’s good or poor.

Famine, on the other hand, carries with it a slew of issues. Constipation, headaches, and hunger pains are the most frequent. Dealing with it may be done in a variety of ways. Many medicines may cause difficulties when taken on an empty stomach, so talk to your doctor about it.

Anything beyond this point isn’t considered regular fasting and should be looked into.

I’ve been following the LCHF/IF diet for quite some time now….. Every third day, I consume approximately 1200 calories with less than 5% carbohydrates. For me, it’s comfortable… But what if he consumes too many ketones? And what could their consequences be? 19

Ketones are normal and are generated by the body instead of glucose for the brain unless you have type 1 diabetes.

Is gluconeogenesis involved in the loss of lean muscle mass caused by starvation? Protein is provided to participants in certain weight reduction trials to avoid the breakdown of lean muscle mass. Does it make sense to you?

No, it’s not. In a multi-part series of essays, I go through the physiology of fasting.

Amino acids (from dietary proteins) are utilized as gluconeogenesis substrates within 24 hours after a meal. The glycerol produced during triglyceride breakdown is then used as a substrate. During fasting, proteins (muscle, for example) are preserved.

Think about it. Do you believe Mother Nature designed humans to store extra energy in the form of fat, only to burn protein instead of fat when we need it? Fasting, on the other hand, preserves protein while burning fat for energy.

I’m not seeking for medical advice; instead, I’m curious about your views on the larger picture, specifically what would happen in a hypothetical scenario like this. You have a very obese individual with type 2 diabetes who has been taking insulin for many years. The following day, stop taking all medicines and fast for three days. Will this person’s blood sugar drop dangerously low if all medications are stopped? I’m aware that blood sugar levels in individuals without diabetes never dip too low while fasting, even if they fast for weeks. I used to believe that fasting was hazardous for diabetics in general, but only if they were on medicine that increased insulin production and couldn’t get enough carbs while fasting.

In a diabetic condition, high and low blood sugar levels are conceivable. This should always be done under the guidance of a medical professional. As you said, non-diabetics do not experience hypoglycemia, but diabetics with high baseline insulin levels are at risk.

We’ve seen this previously, when diabetics on extremely high insulin dosages were able to remain off their medicines but got hypoglycemia once they stopped taking them altogether. It generally goes gone within a few weeks, although customers may suffer symptoms in the interim.

I just learned that even if a T2 diabetic is not on medication, low blood sugars may occur while fasting, which concerns me since I live alone. I am 60 years old and have had T2 since the age of 17. (insulin since I was 15 because I had bad side effects from metformin). I was taking 100 IU of insulin each day before starting a modest diet two years ago. I was consuming 29 units per day after a year and a half of moderate LCHF. I was also motivated to stop up insulin a month ago after seeing your movies. I currently practice a rigorous LCHF diet, have fasted for 24 hours on numerous occasions, and eat two meals each day. I’ve only taken 1-3 units a couple times a week for the last month (I try to keep my levels below 10 mmol). This month, my blood glucose was 7-10 mmol/L with virtually little insulin. I’ve fasted for a day on just water and feel OK, but I’m worried about hypoglycemia when sleeping. Is there truly a danger of hypoglycemia if I give my body time to adjust to eating less carbohydrates? Isn’t it also true that individuals with pre-diabetes should decrease their blood sugar levels? So, what is the best way for a T2 diabetic to fast? Is there a blood sugar level that must be reached before going to bed, or should I take something?

Unless you’re on medicine, the body starts producing glucose when blood sugar levels drop too low to avoid hypoglycemia. Hypoglycemia may occur in individuals who are not taking medication, although this typically occurs when patients have just stopped using insulin and their gluconeogenesis mechanism is likely rusty. The disease typically improves in a few weeks, although it may sometimes persist longer.

Fasting, according to someone I just spoke with, may have an impact on gut microbes (everyone seems to be talking about gut bacteria these days…) Have you heard of this before?

Your gut flora is affected by whatever you eat or don’t consume. It’s debatable if it counts. I believe it is of secondary significance, although there isn’t much data to support this.

I attempt to alternate between a 24-hour fast and extended durations of fasting. Every two weeks, do a three-day fast, or every three weeks, do a seven-day fast. It is very adaptable. Even when I’m fasting, I feel wonderful. I arrive on time to work, bike every day, and sometimes work out at the gym (not very regularly). I’m not on any medications or have any health issues. Are there any risks associated with fasting on a regular basis? I’ve read your fasting blog and listened to your excellent YouTube lectures, and I realize that it’s up to you to experiment as long as it feels appropriate. Even though I’m a nurse, I’m still concerned since I often mix short intervals of fasting (24 hour fasts) with longer durations of fasting. Is there such a thing as too much of a good thing and too much of a risk to my health when it comes to extended fasting?

There are no contraindications if you are in good health, with the exception of children, pregnant women, and nursing moms. Furthermore, if you have diabetes, you may need to modify your medication.

Your thoughts are very well-thought-out. When I attempt to fast, though, I get extreme nausea. Is there anything I can do to make myself feel better or avoid nausea?

Other medicines, such as iron supplements and aspirin, are the most frequent cause. Take a look at this. If it doesn’t work, consider moving to lengthier fasting times.

I’m aware that fasting may raise noradrenaline levels in the blood. My spouse is suffering from atrial fibrillation. Is it true that fasting makes you more prone to arrhythmia?

It’s a distinct possibility. It needs to come to a halt when this occurs.

I’m curious about your thoughts on It Starts With Food by Dallas and Melissa Hartwig, whose Whole 30 program is well-known. In particular, I’m curious about your thoughts on two points: fasting and meal frequency. They recommend eating three meals per day and eating right after waking up, even if you’re not hungry, which I disagree with based on the information on your blog…. They believe that not being hungry in the morning is a sign that your hormones are out of whack….

They claim that leptin is related to food consumption, and that if we eat too late, the whole process is disturbed, and that high levels of leptin and cortisol result…….

Fasting is also considered to be overly stressful and unhealthy for cortisol management if you go without eating for an extended length of time (more than 8 hours), and it may raise stress levels.

Cortisol, they claim, then preserves body fat and so forth. My question is, have you done any study on cortisol and hunger? Do you monitor your customers’ cortisol levels? I suppose if I test my blood sugar while fasting and it’s low, like 3.8 mol, I won’t have an issue, right? Isn’t it common not to feel hungry first thing in the morning….? And I shouldn’t be filling my face with food that my body doesn’t seem to desire right now.

You should not eat if you are not hungry in the morning. It’s referred to as “listening to your body.” It doesn’t mean your hormones are messed up; it just means your body is asking you to stop eating. Then don’t do it.

Leptin is probably unaffected by skipping breakfast. It seems to be a fabrication. You do not have to eat constantly. Cortisol levels aren’t raised by skipping meals. I don’t understand how pushing oneself to eat when you’re not hungry would aid weight loss.

In reality, research on cortisol and fasting are few, and the majority of them are conflicting. In our practice, I don’t test cortisol levels. Dietary modifications will not be particularly helpful if your issues are caused by cortisol (stress). Instead, you must find a way to de-stress (meditation, yoga, massage, pain management, etc.) I try to keep my discussions on food to a minimum.

As part of the circadian cycle, cortisol levels rise in the morning. This is a common occurrence that affects everyone. This allows part of the sugar held in the body to be released, providing energy for the rest of the day.

Your body has already provided you with energy, therefore you don’t need to eat. You have enough sugar to go through the rest of the day without eating. You are not hungry because you are energized. When we eat immediately after waking up, we have typically been training our morning appetite for decades.

Is it conceivable that kidney stones and ketosis are linked? Do you believe that this kind of diet may alter the PH of your blood/urine or do anything else to enhance the chances of stone formation? And, while sticking to the strategy, are there any preventive actions that may be taken?

Unless you drink constantly, there is no link. It is critical to consume adequate water and salt/electrolytes when fasting. This helps to prevent kidney stones from forming.

Ketosis and Intermittent Fasting

A ketogenic diet, I recently read, may cause renal tubular acidosis. Should I be concerned? What are your thoughts on this?

I wouldn’t be concerned. I receive recommendations for all instances of PTA as a nephrologist, and in the past 15 years, I’ve only seen 3 or 4 cases that weren’t related to diet. One of the elements of the ketogenic diet that concerns me the least is ATR.


Blood tests are suggested.

If insulin resistance/metabolic syndrome is detected, which blood test would you recommend?

Fasting blood glucose and hemoglobin A1C are the tests I concentrate on. I also examine ALT for triglycerides and liver fat (indicates a high carb diet).

Can you offer me some basic information regarding the symptoms of cortisol excess? How can I tell whether cortisol is a significant role in my health?

Excess cortisol is difficult to diagnose with precision, although most individuals are aware of their stress levels (mental, physical, chronic pain, etc.).

You have reached the end of the Question & Answer page.

Do you have any additional questions for Dr. Jason Fung regarding fasting? On our membership site, you can read our in-depth interview with him (free trial).


Dr. Fung’s 45-minute presentation on the key to obesity – insulin resistance – and how to reverse it is also available. This presentation may be found on the members-only sites (free trial).


Dr. Fung’s website,, is also worth a look.

One of the fastest-growing diets for weight loss is intermittent fasting, or IF for short, which involves eating during a fasting window and then fasting for a specific amount of time or until food consumption begins again. What are the benefits of intermittent fasting for weight loss? Does it work for everyone? In this blog, world-renowned cardiologist Dr. Fung will discuss the science behind intermittent fasting for weight loss, the different types of intermittent fasting and answer your questions.. Read more about intermittent fasting benefits and let us know what you think.

Frequently Asked Questions

What are the rules for intermittent fasting?

Intermittent fasting is a diet plan that allows you to eat all the food you want, but only for a short period of time.

Why intermittent fasting is bad?

Intermittent fasting is bad because it can cause your body to go into a starvation mode. This means that you will be more likely to burn fat instead of muscle, which is not good for your health.

What should you not do during intermittent fasting?

Intermittent fasting is a diet that allows you to eat normally for an 8-hour window, and then fast for the next 16 hours. It can be helpful in weight loss and other health benefits. However, it is important not to do anything during your fasting hours that would break your fast.

This article broadly covered the following related topics:

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  • jason fung fasting youtube
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