Bariatrics is Surgically Enforced Fasting – T2D 6

posted in: Diabetes, Fasting | 47

Bariatric (stomach stapling) surgery quickly and successfully reverses type 2 diabetes (T2D).  The most recent trial was published in the New England Journal of Medicine on 242 adolescents undergoing bariatric surgery. Most got Roux-en-Y bypass, with most of the rest getting sleeve gastrectomy. After 3 years, the results were good. 74% of high blood pressure resolved. 66% of abnormal lipids resolved. 86% of abnormal kidney function resolved. And Type 2 diabetes? Glad you asked. A stunning 95% of type 2 diabetes was reversed, with a median A1C was 5.3%. (But wait, doesn’t the American Diabetes Association call this a chronic and progressive disease? Don’t experts call this an uncurable disease?)TeenBariatrics

But there are complications. Within 3 years, 13% of the participants required surgical re-intervention. Most of these procedures involved esophageal strictures that required dilatation. The esophagus starts to scar and then it narrows down resulting in difficulty eating. They shove progressively larger sized tubes down the patients throats to open things up (lovely). This procedure is often repeated over and over.

Interestingly, the T2D is often reversed within weeks and far, far before significant weight is lost. For example, a 500 pound man might lose 50 pounds in a few months. That’s great, but that still leaves him at 450 pounds. Despite this weight, T2D is often fully reversed. Why does it work? There are many theories. But it is pretty obvious how bariatric surgery really works its magic. Bariatrics is surgically enforced fasting. But let’s look at the competing hypotheses.

The first hypothesis proposed was that the benefits are due to the surgical procedure itself. Maybe removing part of the healthy stomach or rewiring normal, healthy intestines into an abnormal, artificial man-made configuration somehow improves things. This is very far-fetched, but known as the foregut hypothesis. The normal stomach secretes certain hormones, including incretins. By removing the stomach, some as-yet-unknown hormone that mysteriously induces T2D would also be removed.SurgeryCuresDiabetes5

This is obviously pretty wrong. Gastric banding involves putting a band around the stomach to stop people from eating. This also reverses the T2D despite the fact that none of the stomach as actually removed. If the T2D was due to the mystery hormone secreted from the stomach, the gastric banding surgery would not be effective. But it is almost as effective as the traditional stomach stapling.

The foregut hypothesis would also not explain why T2D often recurs in these bariatric patients years later. Since the stomach is surgically removed, it cannot regenerate the ability to secrete these hormones. Neither has anybody actually figured out what this mystery hormone actually is. This proves the rather obvious point that the removal of healthy stomach doesn’t really have any true benefits.

There was also a hind gut hypothesis. Because the stomach was gone, food moves faster movement to the far reaches of the small intestine. Perhaps this big lump of food would stimulate release of appetite suppressing hormones from the stomach. Except that there is no stomach. Also, there is no big bolus of food because the stomach is the size of a walnut. So, that doesn’t seem to work either. And once again, procedures that did not rewire the intestines seemed to work almost as well as those that did. So, the hindgut hypothesis didn’t make much sense either.

We can compare the effect on insulin sensitivity of different bariatric procedures. Diet, Roux-En-Y bypass and other surgical techniques do not differ substantially in their ability to reduce insulin resistance – it only matters how much weight is lost. It did not matter whether you cut the stomach or not. It did not matter if you rewire the intestines or not.The top two (BPD – Biliary Pancreatic Diversion) refers to a surgery no longer done. The only thing that mattered was the weight loss. ComparingBariatrics

The second major attempt to explain the benefits of bariatric surgery involved total (subcutaneous + visceral) fat. We imagine fat cells sitting there doing nothing like a sack of potatoes all day long. However, that’s not really true. Fat cells (adipocytes) can actively secrete many different types of hormones.

For example, fat cells can secrete leptin, which is a regulator of body weight. Normally, as there are more fat cells, leptin increases and the body tends to go down in weight. Obesity, though is a leptin resistant state. Adipocytes can also take testosterone and turn them into estrogens instead, leading to the familiar phenomenon of ‘man boobs’. So adipocytes are not metabolically inert, but active players in hormone secretion.SubQFat

Perhaps adipocytes themselves can play a role in sustaining obesity and type 2 diabetes. In that case, removing fat cells reduces this mystery hormone and the diabetes goes away. But there are several big problems with this theory. Mainly it does not explain how T2D disappeared within weeks – long, long before these patients had lost any substantial fat mass.

A New England Journal of Medicine study looked at the metabolic effects of liposuction. Surgeons hoped that removing subcutaneous fat cells would improve the insulin resistance of T2D. Proving metabolic benefit of liposuction would secure Medicare funding. Otherwise as a cosmetic surgery, it would remain unfunded. Liposuction can only remove subcutaneous fat (under the skin) and not the visceral (around the organs).SubQFat2

In the study, liposuction removed 10 kg (22 pounds) of the subcutaneous fat. That’s great, but that’s not our question. Was there any metabolic benefit? There was no significant improvement in the blood sugar readings. There was no metabolic improvement, only cosmetic ones.

The subcutaneous fat does not play a causal role in T2D, emphasizing the distinction between visceral and subcutaneous fat. Visceral fat is stored in the organs (predominantly the liver, but also the pancreas) and around the intestines. It is often called a ‘beer belly’ since people often have skinny legs and arms, but a large belly. This is classic, since beer contains lots of carbohydrates and chronic overconsumption often leads to metabolic syndrome. This is also aptly called ‘Wheat Belly’ by Dr. William Davis. Visceral fat is metabolically the most important. Unfortunately, it is also the most common. Fasting and bariatric surgery preferentially removes visceral fat whereas liposuction removes subcutaneous fat. This partially explains why bariatrics leads to metabolic improvement even before all of the weight is lost.  Subcutaneous fat while just does not play much of a role in disease.BariatricsEnforcedFasting

There is no real magic here. All different types of surgery work – because they all have one thing in common – a sudden severe caloric reduction. Simply put – Bariatrics is surgically enforced fasting.FastingCuresDiabetes4

All of the benefits of bariatric surgery accrue because of the fasting. Studies show that fasting is actually superior to surgery in both weight loss and reduction in blood sugars. Patients scheduled for bariatric surgery underwent a period of fasting immediately prior. This would burn a lot of the liver fat. The smaller liver makes surgery easier, especially with the newer laparoscopic techniques. Comparing the effects of the fasting with the surgery right after, fasting was clearly superior in terms of weight lost (7.3kg vs 4kg) and reduction in blood sugars.

We know that bariatric surgery is quite effective at reversing T2D and also, over time, reducing weight. We also know that bariatric is simply surgically enforced fasting. So here’s the crucial question. If all the benefits come from fasting, why not do the fasting and skip the surgery entirely? In essence, fasting is ‘bariatric surgery, without the surgery’. Medical Bariatrics.

Fasting? Are you crazy?

So, why don’t we do it? No good reason. It’s just a little crazy. If I, as a doctor, recommend cutting out a person’s healthy stomach and rewiring their intestines from the normal configuration to some bizarre man-made creation, people think I’m great. If I recommend fasting, which accomplishes everything that bariatric surgery does without any complications or costs, then I’m some kind of crazy Internet guy with a tin foil hat on his head.

We believe that we cannot fast by ourselves, without help. That we are too weak-willed. That it is too hard. That we will all likely fail without help. What is disturbing is that this assessment is made before anybody has even tried to fast.

People say this to me all the time. “I can’t fast for 1 day”. So I ask them, “How do you know? Have you tried it?” To which they answer, “No, I just know that I can’t”. WTF?? How do you know that you cannot fast if you have never tried it. In fact, it is clear that almost everybody can fast. There are literally millions of people around the world who fast for religious purposes on a regular basis. It is part of virtually every major religion in the world. Like anything else, doing it more often makes it easier. But to simply give up without even trying? That’s just wrong.

Likewise, consider the colonoscopy procedure – now routinely done millions of times a year. In order to prepare for this procedure, it is often standard to fast for 24 hours so that there will be less stool in the intestines to get a better view. Is it fun? Not really, but that’s not my point. People can fast if they put their minds to it. It doesn’t take particular skill – almost everybody can do it. This is because fasting is not something ‘to do’  – it’s something ‘to NOT do’. It is the absence of, not the addition of. This makes it almost the exact opposite of every piece of  advice ever given. Take vitamins. Take drugs. Take surgery. That’s probably why fasting is so successful.

So here’s the bottom line. Bariatric surgery has many proven benefits. Multiple studies show a short term benefit, although long term, it is more questionable. Weight loss and T2D are successfully reversed in the short term. But it’s not necessary. Imagine this. Bariatrics without surgical post operative complications. Without cost. Without the need for expensive hospitals or surgical equipment. Without the need for specially trained surgeons. You can simply do ‘medical’ bariatrics – or bariatrics without the surgery – fasting.

For Fasting series start here – Fasting Part 1

Continue to T2D part 7 “Insulin Resistance is Good?

For T2D series start here – My Journey

47 Responses

  1. Great article, but with today being Thanksgiving, there will be NO fasting today!! 🙂

    Happy Thanksgiving Dr. Fung!!

  2. Dr. Fung, I have been following you for a while. I absolutely love your crystal clear thinking, and your crystal clear writing!

  3. Dr.Garry Lee

    Even better than most of your articles SuperJ!

  4. I love your common-sense, brilliant articles and this one top all others so far.
    Can’t fast? Might as well say “can’t walk”. Anyone can abstain; perhaps not for a week but for a day.
    When (after several years of LCHF) I abstained from breakfast and lunch, the remaining belly fat was gone quickly (about 4 days). After having maintained this intermittent fasting for 3 months, I’ve also lost fat elsewhere and feel wonderfully healthy.
    If people eat enough fat in their meals, they can fast for two meals, or perhaps even for two days if before fasting they change their metabolisms from sugar burning to fat burning. This is the most important first step… but you know that.
    Thank you for the work you do to help people escape metabolic syndrome and diabetes.

    • I think the key is that switching T2 and other insulin-resistant people directly from a sugary/starchy/junky diet to fasting is hard. If people feel hungry every 2-3 hrs, going 12 or 24 will seem impossible. But going LCHF first makes the transition to fasting very easy. Just switching from junkfood to a LC real food diet would help people to understand what being satiated feels like again; for some it has been decades. Once I went LCHF and often found myself forgetting to eat and going 8 or more hours before feeling hungry, I was surprised to discover that I was intermittent fasting before I knew what it was. So trying 16:8, 20:4, 1, 2, and 1-week fasts seemed possible and they were, especially when I learned from this site what time frames are involved in high ketone and hGH production.


      Perfect ! All OK.


  5. Thanks Dr Fung. I am still on my intermittent fasting ( at least twice a week for 5 months) and the results are great. Reduced levels of insulin, lost weight ( even though I don’t need to) and HbA1c is at 7. I have only fasted for 24/36 hours at a time and I know I need to try longer periods but I am convinced over time I will reverse my T2D.
    Take care and hope you find time to take a break over the festive season 🙂

  6. Speaking of fat cells, I read an interesting article w/study yesterday about fat cells being generated by bone marrow as opposed to good ol’ carbs (I can’t find it again, but I sent it to Mark’s Daily Apple, and it should make the rounds on Sunday: If we’re generating fat cells through excess carb ingestion AND bone marrow, then a gastric bypass wouldn’t really solve the problem long-term, would it? It would only take care of the excess carb-induced fat.

    As for getting carb addicts to try to fast for even a day, my neighbor who lives behind me says she’s Christian, and she eats 3X daily. She asked me what I was doing for Thanksgiving, and I said I was fasting that whole week. Her eyebrows went up, and she said she could NEVER do that, even for a day! I pointed out that by eating as often as she does, it’s the same as feasting–even Thanksgiving feasting, every day–the food adds up. She’s 57, looks like she’s 87, and has the health problems to go with it. I’m 52, and the difference between us (physically) is striking to say the least. I barely even have gray hair, while she’s getting hers dyed every time I turn around. And the varicose veins–I have none, while she’s covered in them. I remind her that fasting is in the Bible, and as a Christian, isn’t that supposed to be her instruction manual for living? I guess she doesn’t know her bible as well as she claims.

    Ask her to fast? I can’t even get her to eat more fat, so she can skip lunch! A dyed-in-the-wool carb addict, that one is. If it isn’t ADA-approved, she won’t have anything to do with it. I lost 40 lbs. (all post-menopause) over the last 6 mos., while she is struggling to keep off 5 lbs., and always asks how I did it. I told her over and over again about eating low-carb, but she won’t give up her bread, potatoes, pasta, and rice. I then tell her to just skip one meal a day (lunch), and she says she can’t–the hunger is just too great. What does she really know of hunger? She’d rather walk the dog 4x daily (and does) than give up a meal, hoping to work the food off. What she’s doing is eating up time–her dog walks for at least an hour each trip.

    Hunger “just too great?” There are people all over the world who struggle just to eat ONCE a day, and she thinks she’s struggling by feeling the necessity to eat 3X that? She could eat once herself, and feed two more people besides!
    Even the bible won’t stop some people from overconsumption of food–just because it’s available doesn’t mean we have to eat it!!

    (getting back to the subject) Yes, bariatric surgery is unnecessary, but doctors and insurance companies in the U.S. tell you that $50k spent NOW will save $300k later in health costs, so they encourage it WITH CAVEATS. You have to go through (and fail) at least three medically-approved weight loss programs before you have a chance of getting approval for the surgery. My husband got a copy of one program’s folder-full of paperwork and a brochure sent home to him, and I got a look at it: this particular program wanted you to go on Atkins + fruit and grains (a set-up for failure), only with private-label shakes and bars (so you can’t get a look at the ingredients ahead of time, or buy them on Amazon). Their cost just for the products: $5500 for the length of the program, and they wanted you to drive 30 miles one way to go to weekly mandatory meetings, so gas + time spent too.

    He was already doing the REAL Atkins minus the products, because he’s allergic to soy (he still does Atkins induction when he isn’t fasting). I called this program, and got the receptionist to tell me that yes, there’s soy in their products, and he could just do the Atkins Induction part since he couldn’t use the products. HE WAS ALREADY DOING THAT!! That’s when Jimmy Moore turned us on to you and fasting, and we haven’t looked back. We fast 3 days/week, and eat food only once daily on the remaining days (we drink broth, tea, and water the rest of the time). He’s actually lost a little weight, and blood sugar is WELL under control, in spite of being keto for over a year.

    You saved us a $5.5k program expense, and a $50k surgical ordeal, as well as saving us from having to shell out for insulin, needles, and god knows how many other drugs. You saved our insurance company $300k all told. You’re also saving us the cost of meat, and don’t know it–the pig feet, chicken backs, osso bucco, and other stuff I buy for boiling into broth (all pastured) renders about 1.5-2 lbs. of meat bits after every boiling. After straining and removing bones (no matter what size), I let the remaining meat cool, then subdivide into 2/3 cup portions (6 oz.) for the two of us, and freeze for later use. These meat bits can then be used for just about anything: mini meat loafs (after grinding), stir frys, casseroles, burgers (after grinding), thrown back into broth for soup, etc. Whole cuts of meat have become an occasional treat around here (which we share–1 ribeye steak feeds both of us). The cost of pig feet, chicken backs, osso bucco, etc. is cheap, so I actually pay for the bones, and get the meat for FREE.

    If I were in Toronto, I’d seek you out and give you a hug. You saved my husband, saved my grocery budget, and saved my sanity all in one fell swoop.

    • I’m not sure why you found it necessary to Christian-bash. Fasting is in the Bible and there’s a variety of reasons why they fasted in the bible, none of which had to do with physical health, but spiritual concerns. You are practicing the very thing that non-Christians say they hate about Christians: being dogmatic. I’m glad for your success. I’m also fasting and doing a low carb diet and have had great success, but don’t feel the need to put others down. Maybe a gentler approach or letting your neighbor come to her own conclusions may help.

      • I don’t like Christian bashing either, and it’s all over the place. But I do think it’s time for we Christians to be honest with ourselves about how much church life revolves around sugar. The coffee hour in every church I’ve ever been in is much more a sucrose hour than it is anything else. We say we’re the people of life and then we shove sugar at anyone who comes within reach.

  7. This post reminds me of a movie with Meryl Streep in the late 90’s. It was “First Do No Harm,” Meryl was the mother of an epileptic child who was not responding to drugs. The doctor in charge recommended risky surgery. Meryl persevered and discovered a clinic at Hopkins offering ketogenic diets with a demonstrated success rate of 33%. The doctor absolutely refused.

    The take away from the movie is that 99% of medical doctors when confronted with two options: (a) risky surgery, or (b) eat bacon and eggs, will always go with risky surgery. After all, the bacon and eggs might kill you.

    Bariatric surgery, or more accurately described as “barbaric surgery,” is just more of the same. You have two options: (a) risky surgery that screws up your health for life, or (b) don’t eat for two weeks. 99% of the medical profession will always go with option (a).

    It is nice to see that Dr. Fung is in the one percent. Maybe Meryl could be induced to make another movie.

  8. Maura Santangelo

    Dr Fung,

    can intermittent fasting precipitate migraines? I have been on LCHF and done intermittent fasting, dinner to dinner, or occasionally longer for about a year. However during this past week I have had classic migraines with visual aura 3 days in a row. The scotoma has been in different locations each time. Before this I had only had rare migraines when I had untreated sleep apnea, but none for at least 7 years. I am postmenopausal and I am sure that my sleep is now normal. Nothing else has changed in terms of caffeine intake, I do not eat aged cheeses…any thoughts? Thanks

  9. Dr. Fung,

    I am so thankful I stumbled across your blog in June 2015. It was an answer to prayer for me. I have lost 37 pounds since then and I am no where near perfect but I keep going. My glucose and other numbers are improving. My doctor has said “Whatever you are doing works so keep doing it!” This was after I explianed what I was doing and I passed along your blog address to her. Hoping she check it out.
    Thanks again!

  10. I found that article about fat cells being made by bone marrow:

  11. Dr.Fung

    We all look forward to have your updated blog with absolute facts based on research & your unmatched analysis.Keep it up.I wish I knew you before 20 years ago when I was diagnosed Type 2. Thanks a million.

  12. Question about testing of T2D following bariatric surgery and fasting?

    How I hypothesize the process leading to T2D: Insulin resistance starts in the liver as a result of fat accumulation in the liver. This fat accumulation affects the liver’s production of glycogen and other functions. As a result of the fat accumulation, the liver becomes insulin resistant, then the adipocytes and myocytes (they under-responding to blood insulin). In response to higher blood glucose from insulin resistance the pancreas secretes more insulin. Gradually fat accumulates in the pancreas and as you point out in your Sept 3rd blog, “The Biggest Lie”, the pancreas accumulates to a point where its production of insulin declines leading to the diagnosis of T2D (see your chart of “Two Phases of Type-2 diabetes”). With bariatric surgery or fasting the body preferentially metabolizes the fat in the pancreas and liver thereby restoring their normal functions; thereby curing T2D given the current common tests. These patients during the first month are on a low glucose diet, thus the standard measurements of HbA1c and fasting glucose would be fail to detect the glucose resistance in myocytes and adipocytes. And given their forced energy restricted diet, on subsequent tests a year later they would still be cured of T2D.

    Question, has there been for bariatric patients within the first month a glucose clamp measurement to determine if they are insulin resistant? and for those fasting? Note “The gold standard for investigating and quantifying insulin resistance is the ‘hyperinsulinemic euglycemic clamp’,” at

  13. After the surgery is complete, how is surgery fasting instead of chronic caloric restriction, which according to your previous writings is bad? It’s my understanding that patients eat small amounts of food, all the time.

    Dr. Jason Fung: Precisely. After bariatric surgery, patients follow a calorie reduced diet. Then, as their gastric pouch expands, they start to eat more. Of course, they will never fast again. This leads to weight regain and the long term failure of bariatric procedures.

  14. Dr. Fung continues to make the most valuable contribution to the topics of obesity, diabetes and every conceivable disease treatment. Shut your pie hole and improve your health faster than, and to a greater extent than, any other means of treatment. Alas, it’s usually the case that the biggest impediment to improving one’s life, is the small-minded organ that sits between our ears. Thanks so much, Dr. Fung, for the creative insight you had to advise fasting as the most valuable contribution to better health.

  15. Fasting has made all the difference for me. I’ve lost 60 lbs and reached a normal BMI. I tried to get my brother to try it and he opted for surgery instead… Fasting seemed to radical. Oh well.

    I found a paper that you may find interesting and is consistent with your model of insulin in diabetes and obesity: Hyperinsulinemia: A unifying theory of chronic disease?

  16. How can you say that bariatrics and fasting are the same thing – bariatrics is permanent whereas fasting is only very short term. It doesn’t take a genius to figure out why blood sugars normalise quickly in diabetics when little or no food is taken in. There doesn’t need to be any metabolic improvement, let alone cure, for blood sugars to normalise when fasting. The high blood sugars will quickly return upon breaking the fast. Fasting and bariatrics can only be said to cure if full insulin production and sensitivity are permanently restored and neither of them achieve this. The intensive dietary intervention must continue in the faster as it does with the surgery recipient, to keep the blood sugars at safe levels

  17. Michael McEvoy

    Dr Fung

    I have long thought to myself – instead of surgically enforced fasting , why not just do fasting ? Thanks for giving us primary care docs a little more ammo to work with in trying to convince patients.
    In addition , I commented on one of your blog posts with an enquiry about biochemical measurement of Insulin Resistance. It was in the Do All Diets Fail? blog post. I would love to hear your response . Thanks again,

    Mike McEvoy , MD

  18. Dr.S. Vijayaraghavan

    Without doubt low carb diet and intermittent fasting in tandem is the most powerful and sure shot solution to put T2d into remission.
    The beauty is that most of my patients who have knocked off Diabetes continue to fast intermittently, as they see immense benefit in doing so. It has become a way of life, making Bariatric surgery absolutely redundant.

  19. It is so difficult to fast because our whole culture says the opposite. Food companies, the diet industry, doctors, the government, psychiatrists. Like Dr. Fung said in an earlier post, they all say we should eat more, take this pill, eat that food, drink this shake. . . . consume, consume, consume. We get bad advice from all corners. Is it a wonder that friends and neighbors, who are bombarded by the same advice, think we are extreme and a little bit crazy? And is it any wonder that it is so hard to change their minds?

    Anyone who doubts the strength of peer pressure, cultural norms, industry, and authority figures on an individual should study the LCHF movement. I think, for me, I came over to the other side when I listened to and read presentations by multiple doctors about the health benefits of LCHF such as Robert Lustig, Andreas, Jason Fung, and so many others. The doctors I come face-to-face with are intimidating authority figures. Thank God for the internet and those doctors willing to get the LCHF/Fasting message out there.

    Even though I believe 100% that low-carb eating and intermittent fasting are uniquely healthy, I need to read LCHF blogs and forums almost daily to keep my motivation going. That is how entrenched the standard way of thinking about food and health is in our culture. Dr. Nally says it best here:, to wit, “Motivation is like bathing, you have to do it every day.”

    I say we are to be lauded for thinking outside the box and not taking the blue pill, (Matrix reference 🙂 ). We can gently nudge our family and friends in the right direction by sharing the great resources on the internet such as Dr. Fung, Andreas Eendfelt, and all the great low carb bloggers out there.

    • I can confirm that if you’re on a low carb diet, you’re considered to be crazy, but if you say you fast and don’t eat for a while (particularly days), then you’re CRAZY — psychotic. And at one time, for both of these, I would’ve agreed with those comments. Heck, I would run to eat after I worked out. I HAD to have food. Now, I go through a few workouts without eating anything for days, and I basically never eat breakfast any more, so I won’t eat for many hours after working out.

  20. I have been LCHF (keto) since late July. Initially lost about 30-35 lbs, but had hit a bit of a plateau. I was so grateful to find Dr. Fung’s writings and learn about insulin resistance, fasting, and curing all the metabolic syndrome “chronic” conditions. It is fantastic to have another tool in my arsenal, I love eating LCHF, and I love intermittent fasting, which I added about 3 weeks ago, blasting through that plateau. I do think going Keto first really helps the ability to fast without hunger. Personally, I am now off all meds, and with my improved understanding of health, my body is my friend, instead of my betrayer.

    • I also hit a plateau with LCHF. I think I was eating too many meals per day, with too much protein and not enough fat. Intermittent fasting (and adding fat to my diet) has helped a lot. It’s still a struggle, though, particularly at the holidays. The nice thing about fasting, though, is I can do it anytime, even during the holidays. I might not eat breakfast or eat breakfast but not lunch, etc., and limit the damage I’m doing with wheat and sugar.

  21. Kok-Hong Wong

    Since starting on a low carb diet with intermittent 18hr fast, I have effectively reduced my HbA1c from 11% to 6.3% within 9 weeks. But I still occasionally come across several research statements like this “One night of sleep deprivation reduced insulin sensitivity by 33%, whereas 6 months of high-fat diet, reduced it by 21%”

    Where a high fat diets on canine and mouse models points to high fats diet as the cause of insulin resistance. Are we all talking about the same lowcarb high fat diet? Or are they using high carb high fat diet.

    • You have to be careful with any study not done on humans. You never know how well it translates to humans. Also, you have to read the fine print carefully, as often, the “high fat” chow is also high sugar. For that article, I cannot find a link to the actual study, so I don’t know what “high fat” means (nor do I know why a dog would be given a high fat diet in the first place).

      • Plus, these numbers are a bit wacky. Does this mean in three days of sleep deprivation, you’d have zero insulin sensitivity? I find that difficult to believe.

  22. Hi Dr Fung,

    I have been devouring your blog articles for the last few months (thank god, they are carb-gluten-nitrate free!). I have been tempted to go in for the gastric sleeve surgery, but this article of your has finally knocked some sense – and longterm planning/goals – into my head. Thank you.

  23. I have come across similar statements, also of type 1 diabetics reporting reduced insulin sensitivity on high-fat low-carb diets.

    However in the article to which you refer, the phrase “The researchers measured insulin sensitivity in eight male dogs before and after diet-induced obesity.” seems to indicate high-fat without low-carb, as the only way I know to get obese by “high-fat” is by not cutting the carbs… Thus seems they made the dogs obese.

  24. Here’s the up-and-coming successor to bariatrics:

    The procedure, called gastric artery embolization, is usually employed as a nonsurgical way of stemming blood loss by blocking (embolizing) a principle blood pathway.

    Doctors inject microscopic beads into the bloodstream. Normal blood flow then carries them into the arterial region, where blockage occurs.

    The technique is not approved for weight loss. But under an “investigational device exemption,” the U.S. Food and Drug Administration granted permission for a five-patient pilot study to see if the procedure could curtail blood flow to the stomach and thereby suppress production of the “hunger hormone” ghrelin.

  25. Thanks Dr. Fung for a great article on Bariatrics is Surgically Enforced Fasting . There is an interesting article published to day about Type 2 diabetes reversed by losing fat from pancreas,

  26. “If I, as a doctor, recommend cutting out a person’s healthy stomach and rewiring their intestines from the normal configuration to some bizarre man-made creation, people think I’m great. If I recommend fasting, which accomplishes everything that bariatric surgery does without any complications or costs, then I’m some kind of crazy Internet guy with a tin foil hat on his head.”

    I freakin’ love you, Dr. Fung! That is all. 😉

  27. […] Continue to T2D part 6 “Bariatrics is Surgically Enforced Fasting” […]

  28. […] might just be surgically-enforced […]

  29. […] might just be surgically-enforced […]

  30. Dan Duprey

    Very informative article. I’ve been considering surgery as a last resort, having failed at diets and at fasting over many years. By hour 34 of the fast I was in a strange, agitated state, where I could think about Nothing except food.
    But I feel encouraged to try fasting again, maybe for only 24 hours at a time. Still, I prefer the idea of some sort of “enforcement”. I have half seriously considered committing a crime so I’ll be locked in jail…………….

  31. Angelo Carrion

    i’m absolutely fascinated by Dr. Fung and feel like a light has gone off in my mind. I have started intermittent fasting and feel better already. I have roughly a hundred pounds to lose with a great deal of abdominal adipose which is of great concern to me. I am normally a rabid eater once I have breakfast so beginning with 16 hour fasting has helped tame my appetite and hunger pangs. I am not diabetic but given my belly fat I surely have metabolic issues and want to ask if it’s advisable to fast 24 hours and alternate with 16 hour fast every other day? Is it better to fast longer and supplement with broth and sodium for electrolyte control? I appreciate any help from people who have success with fasting.

  32. Dr. Larry Siders

    I’m reading Dr. Fund’s new “Fasting” book. Great stuff. I’m an eye doctor (Optometrist) – witnessing up close the failures of medically controlling T2D.

    This question probably won’t get answered here, but here goes:

    Why does bariatric surgery work when the “Biggest Loser” diets fail (due to decreased metabolism issues)? Both the “Biggest Losers” and the “stomach stapled” patients get 400-500 kCal/day (the “stapled patients are NOT fasting…just severely calorie restricted). Clearly there is a difference…what is it?

  33. I’m not answering for Dr Fung here but as a lap band patient I think it has to do with insulin. The batriatric patient cannot eat much so insulin stays very low almost like in a fasted state. In regards to the biggest loser contestants they are on about 1500 calls a day and a lot of that is carbs so that will trigger more insulin.

  34. Dr Fung, I had a lap sleeve gastrectomy 1 week ago. My blood sugar is now <100 at all times (ie not even a dawn phenomenon). Prior to the surgery – using IF I had reduced my numbers but was still running along at around 160-165 on waking and in the 120 territory otherwise. Since you first wrote this article have any further developments occurred on the research side that might explain the extraordinary speed with which surgery seems to correct the problem? I would also like to test the "enforced fasting" hypothesis. Since surgery I have had frequent – yet very small – amounts of food. Wouldn't the right comparison be not with IF but with a v low calorie, high protein diet?

    Thanks for all you do btw.

  35. Stephanie Waters

    Dr. Fung,
    I would like to tell you that my bariatric surgeon is promoting patients after surgery to follow a LCHF diet for life, which is great. He has given your website out to many patients for reference on how to maintain. I had gastric sleeve almost 2 years ago and can now eat more and got really burned out with the LC diet and found myself cheating tremendously. I’m able to eat more now but not really a lot at one time but have been grazing. I have only gained about 5 lbs but was hoping to lose 30-40 more. I have just now started IF and am really liking this plan, which is surprising. I am not a breakfast person anyway. I said all of that to say I am concerned about fasting a long period of time, having a light lunch, and then not really being able to eat enough at supper to reach the correct amount of protein, carbs, fats, etc. Do you have any advice for me or anyone else that is a bariatric patient? It seems that I still can’t eat a whole lot but I’m not losing due to the types of food I am eating.

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