Fasting Lowers Cholesterol – Fasting 16

posted in: Fasting, Health and Nutrition | 53

How can you lower cholesterol without resorting to medications? High cholesterol is considered a treatable risk factor for cardiovascular disease such as heart attacks and strokes. There are many nuances to cholesterol which I do not want to get into, but traditionally, the main division has been between Low Density Lipoprotein (LDL) or ‘bad’ cholesterol, and High Density Lipoprotein (HDL) or ‘good’ cholesterol. Many people do not look so closely at total cholesterol anymore, because there is both good and bad factions and therefore, the total cholesterol gives us little useful information.

Framingham diet study
Framingham Diet Study

We also measure triglycerides, a type of fat found in the blood. Fat is stored in fat cells as triglycerides, but also floats around freely in the body. For example, during fasting, triglycerides get broken down into free fatty acids and glycerol. Those free fatty acids are used for energy by most of the body. So triglycerides are a form of stored energy. Cholesterol is not. This substance is used in cellular repair (in cell walls) and also used for to make certain hormones.

One might (mistakenly) think that decreasing dietary cholesterol may reduce blood cholesterol levels. However, 80% of the cholesterol in our blood is generated by the liver, so reducing dietary cholesterol is quite unsuccessful. Studies going back to Ancel Key’s original Seven Country Studies show that how much cholesterol we eat has very little to do with how much cholesterol is in the blood. Whatever else he got wrong, he got this right – eating cholesterol does not raise blood cholesterol.

The next thought was that lowering dietary fat, especially saturated fats may help lower cholesterol. While untrue, there are still many who believe it. In the 1960’s the Framingham Diet Study was set up to specifically look for a connection between dietary fat and cholesterol. Why haven’t you heard of it, before? Well, the findings of this study showed no correlation between dietary fat and cholesterol whatsoever. Because these results clashed with the prevailing ‘wisdom’ of the time, they were suppressed and never published in a journal. Results were tabulated and put away in a dusty corner.Tecumseh

The Tecumseh study divided their subjects into 3 levels of blood cholesterol – low, medium and high. Then, they looked at how much fat and cholesterol each group ate. It turns out that each group pretty much ate the same amount of fat, animal fats, saturated fats and cholesterol. So, what they demonstrated was that dietary intake of fat does not have very much to do with cholesterol at all.

Low fat and extremely low fat diets can lower the LDL (bad cholesterol) slightly, but they also tend to lower the HDL (good cholesterol) so it is arguable whether things improve or not. Actually, we’ve known that for quite some time. For example, here’s a study in 1995, where 50 subjects were fed either a 22% or a 39% fat diet. Baseline cholesterol was 173 mg/dl. After 50 days of a low fat diet, it plummeted to … 173 mg/dl. Oh. High fat diets don’t lower cholesterol either. After 50 days of high fat diets, cholesterol increased marginally to 177 mg/dl.

Millions of people try a low fat or low cholesterol diet without realizing that these have already been proven to fail. I hear this all the time. Whenever somebody is told their cholesterol is high, they say “I don’t understand. I’ve cut out fatty foods”. Well, reducing dietary fat will not change your cholesterol. So, what to do? Statins, I guess?

“A little starvation can really do more for the average sick man than can the best medicines and the best doctors” – Mark Twain

Studies show that fasting is a simple dietary strategy that can significantly lower cholesterol levels.

Now, there are many controversies about lipids that I do not wish to get quagmired in. I’m only going to discuss the conventional view of it. That is, many of the classic studies, such as the Framingham study, have pointed out that there is a correlation between high levels of ‘bad’ cholesterol and cardiovascular disease. The higher the LDL, the more bad things happen.


‘Good’ cholesterol (HDL) shows an inverse relationship. High levels are protective. So the lower the HDL, the higher the risk of CV disease. This association is actually much more powerful than that for LDL, so let’s start here. However, it is clear that HDL is not causally related to CV events. They are only a marker for disease.

Several years ago, Pfizer poured billions of dollars into researching a drug called torcetrapib (a CETP inhibitor). This drug had the ability to significantly increase HDL levels. If low HDL caused heart attacks, then this drug could save lives. Pfizer was so sure of itself, it spent billions of dollars trying to prove the drug effective.Bhutani2

The studies were done. And the results were breathtaking. Breathtakingly bad, that is. The drug increased death rate by 25%. Yes, it was killing people left and right like Ted Bundy. Several more drugs of the same class were tested and had the same killing effect. Just one more illustration of the Correlation is not Causation truth.

What happens to HDL during fasting? You can see from the graph that 70 days of alternate daily fasting had a minimal impact upon HDL levels. There was some decrease in HDL but it was minimal.


The story of triglycerides (TG) is similar. While TGs may be correlated weakly to heart disease, they do not cause it. There were several drugs that reduce TG to a much greater extent than the cholesterol medications, the statins. Niacin was one such example. This drug would increase HDL and lower TG without very much effect on the LDL.Bhutani3

The AIM HIGH study tested whether this would have any benefit. The results were stunning. Stunningly bad, that is. While they did not kill people, they did not help them either. And there were lots lot side effects. So, TG, like HDL is only a marker not a causer of disease.

What happens to TG during fasting? There’s a huge 30% decrease in TG levels (good) during alternate daily fasting. In fact, triglycerides is quite sensitive to diet. But it is not reducing dietary fat or cholesterol that helps. Instead, reducing carbohydrates seems to be the main factor that reduces TG levels.


The LDL story is much more contentious. Certainly, there is a correlation between high LDL levels and CV disease. However, the more important question is whether this is a causal relationship. The statin drugs lower LDL cholesterol quite powerfully, and also reduces CV disease in high risk patients. But these drugs have other effects, often called the pleiotropic (affecting multiple systems) effects. For example, statins also reduce inflammation, as shown by the reduction in hsCRP, an inflammatory marker. So, is it the cholesterol lowering or the pleiotropic effects that are responsible for the benefits?

This is a good question to which I do not have an answer yet. The way to tell would be to lower LDL using another drug and see if there are similar CV benefits. The drug ezetimibe in the IMPROVE-IT trial also had some CV benefits, but they were extremely weak. To be fair, the LDL lowering was also quite modest.Bhutani1

A new class of drugs called the PCSK9 Inhibitors has the power to reduce LDL a lot. The question, though is whether there will be any CV benefit. Early indications are quite positive. But it is far from definitive. So the possibility exists that LDL may play a causal role here. This is, after all, why doctors worry so much about keeping LDL down.

What happens to LDL levels during fasting? Well, they go down. A lot. Over the 70 days of alternate daily fasting, there was about a 25% reduction in LDL (very good). To be sure, drugs can reduce them about 50% or more, but this simple dietary measure has almost half the power of one of the most powerful classes of medications in use today.ADF MuscleMass1

In combination with the reduction in body weight, preserved fat-free mass, and decreased waist circumference, it is clear that fasting produces some very powerful improvements in these cardiac risk factors. Don’t forget to add in the reduced LDL, reduced Triglycerides and preserved HDL.

But why does fasting work where regular diets fail? Simply put, during fasting, the body switches from burning sugar to burning fat for energy. Free fatty acids (FFA) are oxidized for energy and FFA synthesis is reduced (body is burning fat and not making it). The decrease in triacylglycerol synthesis results in a decrease in VLDL (Very Low Density Lipoprotein) secretion from the liver which results in lowered LDL.

The way to low ever LDL is to make your body burn it off. The mistake of the low fat diet is this – feeding your body sugar instead of fat does not make the body burn fat – it only makes it burn sugar. The mistake of the Low Carb High Fat diet is this – giving your body lots of fat makes it burn fat, but it will burn what’s coming into the system (dietary fat). It won’t pull the fat out of the body.

Here’s the bottom line for those big-picture, spare-me-the-details kind of folks. Fasting has the following effects:

  1. Reduces weight
  2. Maintains lean mass
  3. Decreases waist size
  4. Minimal change in HDL
  5. Dramatic reductions in TG
  6. Dramatic reductions in LDL

That’s all good. Whether this will all translate into improved cardiac outcomes, I don’t have the answer for you. My guess is Yes.

However, fasting always boils down to this. There’s all these benefits. There’s very little risk. What do you have to lose (other than a few pounds)?

For people worried about heart attacks and strokes, the question is not “Why are you fasting?”, but “Why are you NOT fasting?”

Start here with Fasting Part 1

Continue to Fasting part 17 – Fasting and Hunger

53 Responses

  1. Hmmm….I had blood tests taken while in a 4 day fast. That is, I stopped eating Sunday night and did not eat again until Saturday morning. On Friday, I had blood tests taken.

    Normal, over night fast, 6/7/2015:
    TC: 202
    HDL: 49
    Triglycerides: 120
    LDL: 129
    Pattern B (more atherogenic)
    Fasting glucose: 92
    Fasting insulin: 3.8

    After fasting for 4 days, 9/29/2015 (I include a comparison between this and the earlier test):
    TC: 224 (up)
    HDL: 40 (down)
    Triglycerides: 158 (way up)
    LDL: 152 (way up)
    Pattern A (less atherogenic)
    Fasting glucose: 62
    Fasting insulin: <3.0

    As you can see, my cholesterol indicators got worse while on an extended fast. That is, TC, triglycerides, and LDL went up and HDL went down. Meanwhile, my pattern got better (?).

    I also have numbers such as LDL particle number (went up, which is worse), LP(a) (went up, which is worse), and Apo B (went down, which is better).

    Very confusing numbers.

    • By the way, my cardiologist freaked when the saw the numbers based on the 4 day fast. They did not see the earlier numbers though (which I paid to have done myself). Also, even though the fasting glucose was very low for the 4 day fast, I had no idea it was that low. I suffered no ill effects.

      • BobM, I had the same response to a fast, with increase in LDL, and in fact, it is in the literature that this happens in some people.
        I have no explanation, other than a pet theory – with fasting, I think your liver is pouring out VLDLs, to supple tissues with the TGs (and therefore the FFAs) that they need for an energy source. Since LDLs are the delipidated end product of VLDL, LDL thus increases.
        Dr. Fung, your thoughts? Also, in the “burning fat for energy” state, do you think most of the FFAs are being supplied to the tissues via NEFAs or in the form of TGs in VLDL? Thanks in advance.

        Dr. Jason Fung: While I wish there were definitive studies, my guess is similar to yours. During fasting liver is pouring out VLDL. Normally this would not be an issue, but if you have significant fatty liver and insulin resistance, then the amount coming out is greater than normal leading to higher LDL in the short term which would require more fasting.

        Again, the issue is this. If you are not eating, then where is all that LDL coming from? It must come from your own body, having been ‘stored’ away in the first place in the preceding decades

        • Thanks for your analysis, Newbie and also to Dr. Fung for his additional comments.

          I want to say that I’m not really concerned at all (in fact, I tend to agree with Malcolm Kendrick,, that none of these values matter — except, in my opinion, fasting glucose, insulin, and HBA1c). These results just weren’t what I expected. The only reason I got these tests done was because I had to get them done (Dr’s orders), and they happened to occur while I was trying a seven day fast (of which I made five days).

          On the other hand, on intermittent fasting (IF), I’ve lost another 30 or so pounds in less than a year (lost an additional 20 on low carb before discovering IF), I’ve gone from a 43 inch waist to a 36 inch waist, and I’ve experienced many other benefits. In fact, yesterday, I just finished a three day fast. I don’t plan on stopping IF or low carb because of these results. And I find it difficult to believe that losing 50 pounds is somehow bad for me. I just thought the test results were anomalous.

          I’ll revisit this in February when I get another test done (I’ll use a “normal” fasting test this time!). I’ll see if I can remember to update this when I get the results.

        • Martin Willias

          Is it being ‘released’ or being manufactured de novo? Since most cholesterol comes not from dietary sources but from in-house synthesis, why can we assume that fasting has not stimulated increased LDL production in such cases.

        • Martin Williams

          Is it being ‘released’ or being manufactured de novo? Since most cholesterol comes not from dietary sources but from in-house synthesis, why can we assume that fasting has not stimulated increased LDL production in such cases.

        • I am on day 8 of an extended fast; I have been doing IF & Alternate day for the last 4 months – plus an earlier [within the 4 month period] extended fast of 7 days and another of 14. I’ve lost approx. 30 lbs. I had my annual Health Assessment at work today and my Cholesterol was suuuuper high. More than double any of my previous assessments.

          TC = 303
          HDL = 22
          LDL = 259 [over 100 my previous worst ever measurement]
          TG = 113

          I appreciate the insight regarding potential cause and hope the additional fasting brings that back down. Would it make since to add Omega 3 supplements when fasting to support HDL?

    • Same here. On the seventh of a fast, my blood tests showed that triglycerides went up, HDL went down, and LDL went way up. Unfortunately, I didn’t get tested right before nor right after the fast, so I don’t know for sure how big the changes were (they were striking when compared to my closest test results, but those were pretty far apart from the fast [a year or so on either side]).

      I also had low blood glucose during that same fast, but contrary to you, I felt crummy the whole time. I’m not sure if it was the low glucose or what, but I had a host of “side effects” that made the whole experience quite miserable. 🙁

      It did (temporarily) resolve my hypertension problem, though. So I guess it was not all in vain (it didn’t cure my hypertension, but it confirmed that it was almost surely essential hypertension, which was useful).

    • This is alarming! I wonder if shorter daily IF fasts i:e 20:4 are a better option for some?

    • [email protected]

      That makes perfect sense, because when you go into a deep ketosis, you start burning fat and the body’s cholesterol goes up initially because things get “churned up,” so to speak. I started the Atkins diet in 1998 with cholesterol of 318. After 2 weeks it soared to over 400. After 60 days it went down to under 250. Dr. Atkins wrote in his book to expect it to go up initially and then it would come down. Mine has been around 200-250 since 1998, with HDL ranging from 93 to its highest of 103. My TGs range from 60 to 80.

      I have never seen any persuasive evidence that high cholesterol is connected to heart disease so I am not afraid of it.

    • Here is a couple reference:

      “Smaller LDL particles are more atherogenic (i.e., dangerous) than larger ones. And here’s a key fact pertinent to this discussion: low carbohydrate diets consistently and significantly increase LDL particle size irrespective of the response in LDL-C concentration. Compelling data now indicate that having more small LDL particles is associated with increased risk for heart disease[50].”

      “In the mean time, the ratio of your triglyceride to HDL-C (TG/HDL-C) is an effective surrogate for LDL particle size. Values of TG/HDL-C over 3.5 indicate that you probably have pattern B with a predominance of small LDL particles, and a ratio this high indicates there’s a good chance you may also have insulin resistance[55].”

      Phinney, Stephen; Volek, Jeff (2011-07-08). The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable (p. 95). Beyond Obesity LLC. Kindle Edition.

      While your LDL increased, the pattern changed to less atherogenic. That is important.

    • Said that I would repost once I got new results. Here they are. TC = total “cholesterol”, TGs = triglycerides. The tests taken on 9/18/15 and 3/4/16 were taken after four days (from Sunday night to Friday morning test time) of fasting. The other tests were taken after about 12 hours of fasting. Note that I had one test done on Monday, 2/29/16 after 12 hours of fasting and then a test done on Friday, after 4.5 days of fasting and all the same week. You can see for that week, my TC went up, LDL went up, HDL plummeted, and triglycerides went way up. Of course, my fasting blood sugar plummeted too.

      (Sorry if these columns don’t line up — I’ve tried everything to get them to do so.)

      Date TC LDL HDL TGs Non HDL Glucose HbA1c
      mg/dL mg/dL mg/dL mg/dL mg/dL mg/dL % of Hgb

      6/25/14 175 119 37 113 139 103 5.4
      6/2/15 202 129 49 120 153 92 5.6
      9/18/15 224 152 40 158 184 63 5.4
      2/29/16 168 103 52 65 116 97
      3/4/16 188 121 36 157 152 74 5.2

      However, if you take out the two tests taken while fasting for 4.5 days, and show only the “normal” tests, below is what appears.

      Date TC LDL HDL TGs Non HDL Glucose HbA1c
      mg/dL mg/dL mg/dL mg/dL mg/dL mg/dL % of Hgb

      6/25/14 175 119 37 113 139 103 5.4
      6/2/15 202 129 49 120 153 92 5.6
      2/29/16 168 103 52 65 116 97

      Overall, my LDL is down a bit (NOTE: these are calculated, not measured), but my HDL is way up and my triglycerides are way down. I’m slightly disappointed by my fasting blood sugar and HbA1c (last test was 5.2), as I thought they might be slightly lower, but that’s OK.

      For my cardiologist, I gave him the 2/29/16 test results and NOT the 3/4/16 test results, as I thought the latter would be skewed and they were. He was overjoyed (or at least his staff seemed happy) at the 2/29/16 results

      Also, I really need to get a test taken while not fasting for so long for the pattern. My pattern is still “B”, but the last two tests I’ve taken with the capability to measure this pattern were taken after fasting 4.5 days, which seems to skew the results. Unfortunately, I have to pay for that test, and it’s over $200 just for that, and almost $300 to add in blood sugar and HbA1c. So, it’s too expensive to take frequently.

      • See if you can get an NMR test instead of the VAP type tests, and look at the number and % of small dense LDL (instead of the “pattern A” vs. “pattern B”. Same for the HDL, there are more and less helpful types of HDL, like HDL1 and HDL2 corresponding to different sizes (the bigger the LDL or HDL, the more helpful). This is why there is a contradiction between the LDL number and the LDL pattern (bigger is better but causes the number to creep up).

      • Bob, there are a few portable trigs/chol meters which make your checks quite inexpensive: CardioCheck and Multicare-In
        Higher trigs during fasting could be a result of a sublinical sepsis(bacteria die-off) – google: “endotoxin tryglicerides correlation”
        Eventually, on a highfat-lowcarb diet the trigs/TC should become normal(after 2-4 years)

    • Same thing happened to me. I did the fasting mimicking diet (twice) went and had my lipid panel done a few weeks after and my total cool went up to 232! my HDL went down up slightly, my LDL went up from 96 to 149! and my Tri went up from 51 to 77. Very upsetting.

    • Hi, Just adding a few comments here … after 3 major cardiac events over 10 years… And being told to go home and die..

      New Tactics= Take REPATHA PCSK9 inhibitor, OMAD fasting, LCHF diet…

      After six weeks… LDL down from 7.2 to 2.4…

      TGs down 1.5 to .8.. HDL up 1.3 to 1.6…

      Doctor could not believe results.. Stunned..

      KETONES are PSCK9 Inhibitor.

      BERBERINE Psck 9 Inhibitor..

      Hope that helps somebody..

  2. Dr. Fung, I think your last sentence is suppose to read “Why are you fasting” instead of “what are you fasting”
    Great article, thank you again for all the time you invest for others.

    Dr. Jason Fung: Thanks!

    • While we’re fixing typos – ” PCKS9 Inhibitors ” should read PCSK9 inhibitors.
      Thanks for presenting a clear and uncluttered approach to the lipid related benefits of fasting.

  3. I have the greatest respect for your work and commitment to correcting health myths generated by corporate tobacco science; however I am surprised that you repeat the cholesterol myth and fail to distinguished in analysis of fats the two which causes cardiovascular disease, trans and rancid polyunsaturated fats (rancidification occurs while cooking and also in vivo). Thus studies on fats can find an association of ischemic events with a high fat diet, unless the fat is mostly saturated and monounsaturated fats. Rather than get into the evidence concerning fats and cholesterol, you and others who wish to evaluate the material, I refer you to links at my website,, and on fats at I write this because I seek the best evidence based answer, and if there is compelling evidence that the articles I rely upon are fundamentally wrong, I would like to read those sources of evidence.
    On my video page ( is a link to two short documentaries by the Australian Broadcast Corporation Heart of the Matter Part 1 Dietary Villains, 29 min, 615 views, the saturated fat-cholesterol myth causes heart disease Heart of the Matter, Part 2 29 min 3,800 views. They show that statins don’t save lives, are not safe, and how pharma gets away with the biggest of drug heists. and again at
    Has our KOLs (key opinion leaders) got it all wrong

    Dr. Jason Fung: I am quite aware of the controversy, which is why I stated that I did not want to get quagmired in this entire discussion, and further that I only present the conventional view. Entire books are written on this topic, but this is not my focus.

  4. Has our KOLs (key opinion leaders) got it all wrong? Why worry about total cholesterol, triglycerides, and LDL if the chorus of critics are right? Great harm has according to them be done by chasing the bystander of cardiovascular disease rather than its cause. It is like to use Prof. Ravnskov example blaming the fireman for being at the fire.

  5. Jason Schulz

    Firstly I appreciate your incite into the complexities of the causes of diabetes and metabolic syndrome. I am asking for qualification on the statement that a LCHF diet will allow the use of dietary fat for energy but will not use stored body fat?ie pull the fat out of the body . Does this mean that calorie deficits are needed to use body fat regardless of the fuel used. Also to achieve these deficits it is better to fast than to just lower calories.
    Thank you for any clarification of this.

  6. Thank you, Dr. Fung!

    I wonder whether the Obesity Journal reports a subset of fasters, who, while burning off their own body fat (presumably with a high fraction of saturated fat, like other mammals), end up with a rise in LDL-C ? I will look for that study.

    I have read that some of us do fail to lower LDL with significant weight loss on a low carbohydrate diet, perhaps only among those with a higher intake of saturated animal fats.

    I experienced a dramatic rise in total and LDL-C during a period of severe stress, and have seen that reported in the literature as well.

    Perhaps some of us experience fasting as a stressor when it is not a cultural or religious practice like it was on Crete.

    I am just sitting here generating more hypotheses, which someone, somewhere may have already investigated.

    Thanks again,
    — Jane

  7. Could it be that stuff is being released from body stores and is dumping into the blood for excretion removal? If anything, you should fast LONGER. When Jimmy Moore undertook his longest fast (he made it 17 days before blood sugar levels scared him out of it), his blood sugar got into the mid-triple digits–Dr. Fung told him it was stored triglycerides coming out of storage, and being broken down into the individual components (glycerol, etc.) to be routed through the circulatory system, then excreted. In other words, the rise was temporary, and Jimmy should’ve kept on fasting to finish the process.

  8. Wenchypoo
    Are you saying that Jimmy Moore had an INCREASE in blood sugars while fasting?

    Dr. Fung
    Thank you for this info re fasting and blood fats. I, like others, have had a dramatic increase in my LDL while losing 30 pounds on LCHF and intermittent fasting. I have been quite concerned.
    My doctor put me on statins and after 2 months the LDL has NOT lowered. Why take them, I ask myself.
    I have been ingesting considerable amounts of fat and am now going to lower that temporarily (until the diabetes is “cured”) and fast more. Hopefully by that time the blood fats will be lowered also.

  9. I started paying for my NMR lipid profiles about three years ago. This was one way to monitor dietary changes, and also fasting. These tests have quite a lot of variation, and I would be leery of inferring too much from one test. If you fast periodically, I would look at the lipid profile over a much longer period of time, say at least a year. All kinds of things can influence your lipid profile, so I recommend trying to decipher a trend over a long period of time.

    Fasting blood sugar varies by time of day, maybe even time of year. If it is between 70 and 100 you are normal, and even if it is 65 or slightly above 100 there is probably nothing to be concerned about. The easiest way to lower fasting blood sugar is just to measure it very early in the morning.

    My point here is that there is a lot of noise in medical tests, especially as they are affected by dietary changes, so you need to look at long periods of time and take multiple tests to reliably infer anything.

  10. Douglas Weber

    I have a question about the effects of being chronically hyperinsulemic due to insulin resistance: Is anybody aware of any research showing that high levels of insulin and/or IGF could lead to an overgrowth of soft tissue in general in addition to obesity? I’m thinking specifically of the oversized tongue, large tonsils, and excess soft palate tissue that can contribute to obstructive sleep apnea. Perhaps even an overgrowth of the turbinates in the sinus. Aside from fat loss, do you think it’s possible that fasting could directly help these problems?

    Dr. Jason Fung: Yes, I believe insulin contributes to this problem.

    • [email protected]

      Dr. Fung, would that explain my chronic throat clearing? I have had this problem for about 10 years. I also snore very often.

      • Yes I never snored during sleep for the entire life. Sleep was very calm. Then I was put on insulin being type 2 diabetic and I started to gain weight. Ultamately with three years gradually I started snoring and mean time I also developed the arthritis pians in both shoulders , both hip joints and lrft hand joints.Thanks to Dr Fung, his reseach saved my life. After reading research of Dr Fung I started fasting, on very first day by 5 pm I could go no longer and I broke my fast. Very first fast only just 10 hours. In start I simly did only day time fast means a cup of morning tea and than dinner. After about two weeks, I was able to fast for complete one day mean dinner to next day dinner. Then 2 days fast and 2 days normal meals. Sometimes a complete week off. I complerted 2 water fasts for three days. Now by fifth month I am in my first 10 days fast. To day is my seventh day. I am so happy because to day was the first day, after long time, when my moring reading came 112. For the last seven days not a even single unit off insuline. So my diabetic medine are off. My blood pressure which use to 165/105 is normal. My recurrent kidney infections have been comletly clear. Far the last two days I am free of joint pains. And I have completely stoped SNORING. Hats off to Dr Fung efforts, to save the millions of miss guided people from pill pushers.

  11. Richard Batty

    Ok. Fasting can give bad cholesterol results in the short term. So what would be required for long term results?

    How many times would you have to repeat a 4 day fast? Would it be better to have a longer fasting period? Would it be better to have many for short fasts?

  12. Honora Carroll

    Dr. Fung, I really appreciate all the information you share with us. I have started following your program and look forward to reducing my insulin resistance. Do you feel that increasing resistant starch, by eating potato starch, wouldl help reduce insulin resistance? If so, would one consume potato starch on both fasting and feeding days? Thanks for all you do.

  13. I also experienced elevated lipids while doing intermittent fasting. After receiving my first test results I implemented chia seed pudding made with almond milk daily. This was the only change I made. These are the results:

    First test Sept 11 –
    cholesterol 8.47 mmol/L; LDL 5.64; HDL 2.26; Chol/HDL 3.75; Non HDL 6.21; Triglycerides 1.25
    Second test Oct 26 –
    cholesterol 5.76 mmol/L; LDL 3.56; HDL 1.86; Chol/HDL 3.10; Non HDL 3.90; Triglycerides .75

  14. Lori Blackwood

    I am not overweight but have elevated cholesterol numbers, the doctor wanted to start me on meds, I refused and want to handle on my own first. My glucose has also increased to 4.9. I can tell in the last few months that it has gotten worse with the extreme dehydration I am having. So I am back in the gym, low carb diet, no wine :), and this is my first week of IF where I fast from 7:00pm until 12:00 pm each day and I watch my intake not for weight loss but sugar control. Although I lost two pounds this week. How long does an IF low carb diet take to change glucose intolerance? Do I have the right IF diet? Any help would be appreciated because I would rather handle this then take meds. Thanks so much!

    • Try losing 5 to 10 lbs. I know your not over weight but it’ll help your lipid panel I’d bet.

  15. charles grashow

    Jimmy Moore says he’ll be using his proposed 30-40 day fast to scam his insurance company. Lower cholesterol numbers = lower rates. Sounds illegal to me.

    • It is scammy, but it’s not illegal. Some smokers quit for a few days before applying for insurance, some people lose weight befor a weigh in, they mislead wrt the amount they exercise or drink, for example.

      Insurance companies are usually more concerned about declining cover (or charging higher rates) if your cholesterol is high, rather than giving discounts if it’s low.

  16. Thanks Dr Fung, another great article. What happened to me when I went LCHF was that my LDL rocketed, and if you trawl through many paleo forums online, you will see this happens to a lot of people. Clearly there is some connection between fat in our diets and cholesterol levels, although maybe that only happens with a proportion of us – perhaps to those with a gene defect that prevents us processing fat adequately? I don’t know. I have seen discussions online by Paul at and Ivor at where they discuss various theories, but I would love to hear your take on it, Dr Fung.

    Thanks from Hong Kong.

  17. […] Continue to Fasting Part 16 – Fasting Lowers Cholesterol […]

  18. Bas
    I know only that there is two type o cholestrol but
    By reading this articale and those comments i became very
    interested in this subject very interesting, I am going over this
    Articale aģain and again………….

  19. […] Simply put, during fasting, the body switches from burning sugar to burning fat for energy. Free fatty acids (FFA) are oxidized for energy and FFA synthesis is reduced (body is burning fat and not making it). The decrease in triacylglycerol synthesis results in a decrease in VLDL (Very Low Density Lipoprotein) secretion from the liver which results in lowered LDL. Learn more […]

  20. Thank you so much for the blog!
    I have been lowering my processed food intake over several months although not strict & have tried a little 22/2 IF fasting.
    About 3mnths ago my gallbladder has flared up with constant pain (I should be having it removed next week)
    While having tests for this I was told that cholesterol is high 6.9 &I need to seek treatment,
    My blood pressure is up (tried to explain that I am in pain).
    I am aprox 15kg over weight also.
    I have decided not to take statins or blood pressure medication, after much reading.
    Once I Have recovered from surgery, (3 weeks or so laters) I’ll work the fasting up to a regular 2 or 3 days a week for a few months while eating low carb moderate protein & then
    have tests again.
    Comments appreciated
    Thank you?

    • Maybe try minimizing the time you can run a mile. Don’t go for distance as the extra 15 kilograms will beat up your joints. A 9 minute mile would be a good initial goal. This will help your lipid panels, if that’s what you want.

  21. Roberta

    I, too, have had similar results with increase in my total cholesterol and LDL after a 5 day fast. My total cholesterol went from 257 to 297; my LDL went from 130 to 198. My HDL remained essentially unchanged from 74 to 75. I was so disappointed in the increase in numbers. I, too, wonder how long a fast is needed to see good changes, and if intermittent fasting will do the trick. Dr. Dung what kind of fasting do we have to do to see a drop in our LDL instead do an increase..

  22. […] Só coma quando têm fomee considere a adição de jejum intermitente (isso consistentemente reduz os níveis de colesterol). […]

  23. Why are people so upset when getting high blood levels of FFA ‘s during fasting periods? They should be rejoicing because it means the fasting is WORKING! and releasing their fat from the freezer so to speak. I don’t think it makes sense to wig out about high levels of blood fats when you are doing precisely the thing designed to release fats into the blood to be burned for energy. High blood fats would be expected during active fat burning as this is the stored food becoming available for use. I’d rather have this scenario than “perfect” blood panel and 100 extra ponds of fat layered like an onion all over my body. Am I being too simplistic in my view?

  24. […] fasting has been shown to help lower bad cholesterol. Decreased inflammation following the practice of IF is huge for heart health as well as […]

  25. Thanks Dr :Jason for this v.useful article, i am suffering from high TG levels since last 7 years, the range is 300-490 , whereas Total Cholesterol, LDL, comes in normal range, so decided to fast , (v.small portions of food or liquid diet), there is lot of effects felt within 5 days of fasting, stomach felt totally relaxed, though no improvement in waist measurement, the people who had blood test within 5 days of fasting and had shootup in their test , is too immature test, i can myself feel very strongly the effect of fasting in a positive way , just one big side effect – weakness , specially on the brain side, its very natural , that lipid profile will definitely 1000% will be reduced in drastic way with fasting, as body can only produce lipids to a limit and its can’t convert water or low diet or fasting into high lipids levels which many ppl saw in their blood test after testing.

  26. Liz McCarthy

    May I ask a question? I need help. My cholesterol total is 460, HDL 84, TG 64, LDL 350, should I fast to reduce the cholesterol or take medicine first? Thank you very much.

    • It depends if you already have a cardiovascular related diagnosis indicating the possibility of an imminent cardio event. In my view, more importantly is how far you are willing to go to bring those numbers down and do you have a lot of weight to lose. Time-restricted feeding and no added oils, no added sugar, no animal products, no flour or carbs that spike postprandial blood glucose all helped me. Pick and choose how far you are willing to go, but most important singular one is fasting and time-restricted feeding. Don’t eleive the low-carbers who say you can eat four eggs cooked in coconut oil for breakfast – they are believing what they want to hear. There is evidence that fasting and TRF signal the body to repair itself, worn tissues are broken down and rebuilt when you eat again. Pick and choose from Dean Ornish, Valter Longo and maybe Dr Rhonda Patrick. Good luck. (My total cholesterol was 7.9, now 4, LDL was 6, now 2.5, BMI was over 30, now 21).

  27. An animal adapts optimally to their environment is an axiom which certainly favours IF and paleo.

  28. MachineGhost

    Oxidized LDL is the real problem, not LDL per se. So it’ll be interesting to see how throwing the baby out with the bathwater with the new PCKS9 inhibitors will fare for long-term outcomes. My suspicion is it will trade one problem (CVD) for several others since LDL is critical for transporting lipids and nutrition systematically.

  29. I’m freaking out . My cholesterol is 318 and tri is 200 . Never been this high before . I was on Lipitor and stopped for two months .just had blood work . Diabetic type two also . Thought I was doing good .. guess not

  30. Berkeley

    Dr Fung,
    After intermittent fasting for several months my triglicerides went down significantly (142 from 205); my HDL same( 65 was 66); LDL up significantly ( 250 up from 173) non hdl up (278 from 214). If I continue on this course of action will my liver adjust, and will my ldl normalize? My primary care physician wants to put me on statins. I am resistant to more medications. Your opinion?

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