How to Sync Your Central Circadian Clock to Your Peripheral Clocks

How to Sync Your Central Circadian Clock to Your Peripheral Clocks
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Bright light exposure synchronizes the central circadian clock in our brains, whereas proper meal timing helps sync the timing of the clock genes throughout the rest of our body.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

One of the most important breakthroughs in recent years has been the discovery of “peripheral clocks.” We’ve known about the central clock, the so-called suprachiasmatic nucleus, for decades. It sits in the middle of your brain, right above where your optic nerves cross––allowing it to respond to night and day. Now we know there are semi-autonomous clocks in nearly every organ of our body. Our heart runs on a clock, our lungs run on a clock, our kidneys run on a clock. Up to 80 percent of the genes in our liver are expressed in a circadian rhythm; our entire digestive tract does too.

The rate at which our stomach empties, the secretion of digestive enzymes, and the expression of transporters in our intestinal lining for absorbing sugar and fat all cycle around the clock. So too does the ability of our body fat to sop up extra calories. The way we know these cycles are driven by local clocks, rather than being controlled by our brain, is that you can take surgical biopsies of fat, put them in a petri dish, and still watch them rhythm away.

All this clock talk is not just biological curiosity. Our health may depend on keeping all these clocks in sync. Think of it like a child playing on a swing. Imagine you’re pushing, but you become distracted by other goings-on in the playground, and stop paying attention to your timing. So, you forget to push, or push too early or too late. What happens? Out of sync, the swinging becomes erratic, slows, or even stops. That is what happens when we travel across multiple time zones or have to work the night shift.

The “pusher” in this case are the light cues falling onto our eyes. Our circadian rhythm is meant to get a bright light push every morning at dawn. But if the sun rises at a different time, or we’re exposed to bright light in the middle of the night, this can push our cycle out of sync and leave us feeling out of sorts. That’s an example of a mismatch between the external environment and our central clock. Problems can also arise from a misalignment between the central clock in our brain and all the other organ clocks throughout our body. An extreme illustration of this is a remarkable set of experiments suggesting even our poop can get jet lag.

Our microbiome seems to have its own circadian rhythm. Even though they’re down where the sun don’t shine, there’s a daily oscillation in both bacterial abundance and activity in our colon. Interesting, but who cares? Check this out: if you put people on a plane and fly them halfway around the world, then feed their poop to mice, they grow fatter than mice fed preflight feces. Though it may have just been bad airline food or something, the researchers suggest the fattening flora was a consequence of circadian misalignment. Indeed, several lines of evidence now implicate “chronodisruption”—the state in which our central and peripheral clocks diverge out of sync—as playing a role in conditions ranging from premature aging and cancer to mood disorders and obesity.

Bright light exposure is the synchronizing swing pusher for our central clock. What drives our internal organ clocks that aren’t exposed to daylight? Food intake. That why the timing of our meals may be so important. Removing all external timing cues by locking people away under constant dim light, researchers showed you could effectively decouple central from peripheral rhythms just by shifting meal times. They took blood draws every hour, and even took biopsies of their fat every six hours, to demonstrate the resulting metabolic disarray.

Just as morning light can help sync your central clock in your brain, morning meals can help sync your peripheral clocks throughout the rest of your body. Breakfast-skipping disrupts the normal expression and rhythm of these clock genes themselves, which coincides with the adverse metabolic effects. Thankfully, they can be reversed. Take a group of habitual breakfast skippers, and have them eat three meals at 8am, 1pm, and 6pm, and their cholesterol and triglycerides improves compared to taking meals five hours later at 1pm, 6pm, and 11pm. There’s a circadian rhythm to cholesterol synthesis in the body, too––which is also strongly influenced by food intake, as evidenced by the 95 percent drop in cholesterol production in response to a single day of fasting. That why just a few hours’ shift in meal timing can result in a 20-point drop in LDL cholesterol, thanks to eating earlier meals.

Please consider volunteering to help out on the site.

Image credit: Ilona via pixabay. Image has been modified.

Video production by Glass Entertainment.

Motion graphics by Avocado Video.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

One of the most important breakthroughs in recent years has been the discovery of “peripheral clocks.” We’ve known about the central clock, the so-called suprachiasmatic nucleus, for decades. It sits in the middle of your brain, right above where your optic nerves cross––allowing it to respond to night and day. Now we know there are semi-autonomous clocks in nearly every organ of our body. Our heart runs on a clock, our lungs run on a clock, our kidneys run on a clock. Up to 80 percent of the genes in our liver are expressed in a circadian rhythm; our entire digestive tract does too.

The rate at which our stomach empties, the secretion of digestive enzymes, and the expression of transporters in our intestinal lining for absorbing sugar and fat all cycle around the clock. So too does the ability of our body fat to sop up extra calories. The way we know these cycles are driven by local clocks, rather than being controlled by our brain, is that you can take surgical biopsies of fat, put them in a petri dish, and still watch them rhythm away.

All this clock talk is not just biological curiosity. Our health may depend on keeping all these clocks in sync. Think of it like a child playing on a swing. Imagine you’re pushing, but you become distracted by other goings-on in the playground, and stop paying attention to your timing. So, you forget to push, or push too early or too late. What happens? Out of sync, the swinging becomes erratic, slows, or even stops. That is what happens when we travel across multiple time zones or have to work the night shift.

The “pusher” in this case are the light cues falling onto our eyes. Our circadian rhythm is meant to get a bright light push every morning at dawn. But if the sun rises at a different time, or we’re exposed to bright light in the middle of the night, this can push our cycle out of sync and leave us feeling out of sorts. That’s an example of a mismatch between the external environment and our central clock. Problems can also arise from a misalignment between the central clock in our brain and all the other organ clocks throughout our body. An extreme illustration of this is a remarkable set of experiments suggesting even our poop can get jet lag.

Our microbiome seems to have its own circadian rhythm. Even though they’re down where the sun don’t shine, there’s a daily oscillation in both bacterial abundance and activity in our colon. Interesting, but who cares? Check this out: if you put people on a plane and fly them halfway around the world, then feed their poop to mice, they grow fatter than mice fed preflight feces. Though it may have just been bad airline food or something, the researchers suggest the fattening flora was a consequence of circadian misalignment. Indeed, several lines of evidence now implicate “chronodisruption”—the state in which our central and peripheral clocks diverge out of sync—as playing a role in conditions ranging from premature aging and cancer to mood disorders and obesity.

Bright light exposure is the synchronizing swing pusher for our central clock. What drives our internal organ clocks that aren’t exposed to daylight? Food intake. That why the timing of our meals may be so important. Removing all external timing cues by locking people away under constant dim light, researchers showed you could effectively decouple central from peripheral rhythms just by shifting meal times. They took blood draws every hour, and even took biopsies of their fat every six hours, to demonstrate the resulting metabolic disarray.

Just as morning light can help sync your central clock in your brain, morning meals can help sync your peripheral clocks throughout the rest of your body. Breakfast-skipping disrupts the normal expression and rhythm of these clock genes themselves, which coincides with the adverse metabolic effects. Thankfully, they can be reversed. Take a group of habitual breakfast skippers, and have them eat three meals at 8am, 1pm, and 6pm, and their cholesterol and triglycerides improves compared to taking meals five hours later at 1pm, 6pm, and 11pm. There’s a circadian rhythm to cholesterol synthesis in the body, too––which is also strongly influenced by food intake, as evidenced by the 95 percent drop in cholesterol production in response to a single day of fasting. That why just a few hours’ shift in meal timing can result in a 20-point drop in LDL cholesterol, thanks to eating earlier meals.

Please consider volunteering to help out on the site.

Image credit: Ilona via pixabay. Image has been modified.

Video production by Glass Entertainment.

Motion graphics by Avocado Video.

Doctor's Note

If light exposure and meal timing helps keeps everything synced, what happens when our circumstances prevent us from sticking to a normal daytime cycle? We’ll find out next week in The Metabolic Harms of Night Shifts and Irregular Meals.

If you’re just coming into the series, be sure to catch up with:

If you haven’t yet, you can subscribe to my videos for free by clicking here.

115 responses to “How to Sync Your Central Circadian Clock to Your Peripheral Clocks

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  1. Time for me to change the subject again… sorry, but I have an unrelated topic once more:

    I would like to request that NF.org revisit the topic of oxalates in plant foods, not only quantities, but also bioavailability. I did an informal survey of google-listed “tables of oxalates” and found there is a variety of presentations and units of measure out in google-land. Some of what I found was disturbing.

    Of course, we all know about spinach, chard, and beet greens… off the charts in oxalates. Risky if you are prone to forming kidney stones from calcium oxalate. But various tables posted on the internet show a dismal picture (oxalate content) for many beans, raw garlic, beet root, parsley, chives, almonds, sweet potatoes, and many other plant foods I’ve been eating. Should we be avoiding all plant sources that have high oxalates? Or does bioavailability play a role as well?

    https://veganhealth.org/calcium-part-3/

    https://www.researchgate.net/figure/Oxalate-content-of-foods_tbl7_280910483

      1. Thanks, Barb. Good info.

        I too have wondered about any relation between uric acid (gout and kidney stones) and calcium oxalate stones. If one is at risk for calcium stones, might he/she also be at risk for uric acid load and possible gout/kidney stone attacks?

        Right now I’d be happy just to know I can put parsley back in my stew… =]

    1. dr cobalt,

      I have no idea if this is applicable, but my husband suffered from bladder stones before we met, one every few years. I thought it was because he didn’t drink enough liquids (I call him a gerbil.) But since he met me 12 years ago, and stopped eating processed foods and meat and started eating first vegetarian food and then a few years ago whole plant foods, he hasn’t had one. And he still doesn’t drink enough, though very recently he started drinking a bit more.

      And we eat all the foods you listed above, even spinach and chard and beet greens (I grow the latter two in my garden during the summer). But we eat a variety of different veggies and other foods, so usually not too much of any one thing at one time. Though we do try to eat 3 servings of beans a day (1/2 cup per serving), but don’t reach that goal every day. (We use the Daily Dozen as a guide.)

      So my questions would be: Does eating whole plant foods decrease the risk of bladder and kidney stones? If so, why?

      1. Is there any aspect of health that doesn’t improve on a WFBP diet?
        Are spinach, chard, beet greens, beans, raw garlic, beet root, parsley, chives, almonds, sweet potatoes healthy?
        Can you believe anything you read on the internet?

        1. Hi, Blair! As long as Optimal Nutrition Recommendations are met, a WFPB diet should improve overall health. More on that here: https://nutritionfacts.org/2011/09/12/dr-gregers-2011-optimum-nutrition-recommendations/ Yes, spinach, chard, beet greens, raw garlic, beet root, parsley, chives, almonds, and sweet potatoes are healthy. Dr. Greger does not tell people to avoid eating them. It may be wise for some people to limit their intake of the highest oxalate foods. More on that here: https://nutritionfacts.org/topics/oxalates/ You can believe some of what you read on the Internet, but I would suggest looking for information that is clearly evidence-based. Below each video window here on NutritionFacts is a “Sources Cited” link you can click to access the evidence yourself. I hope that helps!

          1. “It may be wise for some people to limit their intake of the highest oxalate foods.”
            – – – – –

            Those who drink a lot of smoothies probably get a huge amount of oxalate foods, whether they’re good for them or not. Maybe they should cut back on these smoothies and just chow down on a much lower proportion of steamed or raw veggies.

            (I don’t “smoothie” unless I’m visiting NYC. There’s a great smoothie joint somewhere near Lex. and 42nd Street.)

            1. “Those who drink a lot of smoothies probably get a huge amount of oxalate foods, whether they’re good for them or not. Maybe they should cut back on these smoothies and just chow down on a much lower proportion of steamed or raw veggies.”

              No. Smoothies have excellent health benefits as shown in at least one video here on bioavailability and they’re a wonderful way to get lots of great stuff in you. I turned my health around from almost dying due to a moron and piece of crap doctor and his intern unwittingly stabbing (to say the least) me in the liver (no pain killers either, they were great people) and almost killing me and totally screwing up my entire body (more awesome than you suspect, no lawsuit because they lied on documents and my state is horrible for protection of patients) by going vegan and then WFPB vegan relying heavily on smoothies. They continue to be my breakfast of choice and my health is extraordinary and even my vanity relies on such healthy additions to my diet which indeed also includes steamed veggies, because all this stuff is AMAZING for your skin, hair, whites of your eyes and simply everything. Although, do swish mouth with water after tea and berries and the like when you drink/eat as much as I do, to avoid staining.

              In the summer, I go out and pick fresh kale and other greens for my breakfast, it’s the best.

              1. S, it sounds like you’ve run into a lot of incompetent (or corrupt) people in both the medical and legal fields. It’s great that you were able to come out the winner health-wise, at least!

                If I didn’t love my breakfast, lunch and dinner menus so much I’d try to fit a smoothie in there somewhere. But as I’ve posted before, I have to take public transportation and would need to spend a lot of time shopping and busing just to buy the material for one smoothie.

                1. Thanks, YR. Yeah it is astonishing how corrupt those in the medical field can be if they choose to when the laws are set up do poorly, it has really been a nightmare that I still am dealing with and it has costs me so much money—very long and awful story—but indeed I got my health back and then some!

                  Great to have a menu you enjoy, I think it’s so important to eat healthy AND enjoy your diet. I highly recommend a garden—its SUCH a convene ceremony in the spring/summer/early fall to not have to run out for produce constantly.

            2. Is that the $9 smoothie you once told us about YR? I bet it’s good! I don’t drink smoothies as rule either, but they might be an idea to get veggies into kids.

      2. Dr. J,

        I understand and agree with you. But even Dr. G has warned about the high oxalate content of the three I mentioned up front.

        https://nutritionfacts.org/video/kidney-stones-and-spinach-chard-and-beet-greens-dont-eat-too-much/

        Are you so sure that you and your husband will never be at risk eating those three?

        That’s why I wanted to ask for a review. According to the charts it’s more than spinach, chard, and beet greens that have high oxalate content. Parsley has over 1000mg oxalate for each 100 gm.

        1. dr cobalt,

          There are no guarantees of any particular outcome, only risks for them. I can’t predict the future.

          But 100 grams of coarsely chopped fresh parsley is about 4 cups (http://www.cookitsimply.com/measurements/cups/parsley-fresh-coarsely-chopped-0070-016m2.html). I don’t think we ever eat that much at one time; generally, a recipe will call for a tablespoon to 1/4 cup, which is about 6.25 grams per 1/4 cup, or about 62.5 mg oxalate per 1/4 cup (using your figure of 1000 mg oxalate/100 gram fresh (?) parsley) — and these recipes usually serve 4 or 6, which would be about 15 or 10 mg oxalate per serving. (Sadly, since we buy parsley by the bunch in winter (and a bunch weighs about 2-3 ounces, which includes the stems which I mostly cut off), and eat so little of it at a time, it tends to go bad in the fridge, because we don’t eat it fast enough.)

          But of course each person will decide for themself what level of risk is acceptable, hopefully balancing the benefits against the risks.

          1. Hmmm…. I have parsley smoothies, among others–and for that, I use a bunch of parsley along with some liquid and fruit…. Do I need to revisit whether that practice is safe?! I rotate the greens in my smoothies with other greens so I don’t have parsley smoothies every day or even every week. I cycle through parsley, cilantro, arugula, kale, lettuce (yes, even lettuce,) basil, collards, beet greens, spinach, etc.–whatever I happen to have gotten from my local farm here in Michigan (even during the winter.) Lately, I’ve had tat soi smoothies….

          2. […we buy parsley by the bunch in winter… and eat so little of it at a time, it tends to go bad in the fridge, because we don’t eat it fast enough.]

            Cilantro is worse. I can’t get that stuff to last more than about 5 days in the fridge.

            You know how the supermarkets like to spray water on their fresh produce – just about everywhere? And you know how we all think they do that so the produce will stay fresh longer? Um… I don’t think so anymore. I think it’s done so it will stay fresh LESS long, so you will throw it out sooner and buy more.

            Here’s what I do with virtually all of my produce: I bring it home, spread it out on paper towels, and let it become completely dry. Then I wrap it up (sometimes in alum foil – a Martha Stewart trick) and put it in the fridge. Try wrapping dried, fresh asparagus in alum foil… the tips rarely go bad early.

            With parsley and cilantro, I do the same thing – dry it out completely, even overnight, if necessary. Then I separate the stems from the leaves, discard the stems, chop up the leaves, and put them in a zip lock bag. This goes not in the fridge, but in the FREEZER. What I’ve found is that you will NEVER discard decayed parsley or cilantro again. You will use it all up without loss.

            Yes, I know there is a “blanch first” crowd out there who insist on blanching before freezing. But until someone informs me of a health risk, I will continue to freeze chopped parsley and cilantro. Otherwise, it’s just not worth buying it.

            Just sayin’

            1. The veganhealth.org table lists oxalate content of chopped parsley at 63 mg per Tablespoon. That would be 252 mg per quarter cup. Still too high for my cautious timbre. I’d like to learn more about calcium and bioavailability.

      3. Don’t know the why, but I can also attest to this result. I had been a kidney stone former. Like clockwork every ten years I would have stones. Overtime, I became a plant eater almost exclusively, with the occasional seafood. Anyway, I eat plenty of oxalate containing foods and enjoying life without the stones. BTW, also had a history of not hydrating. I keep up with the literature and wonder if the recommendations on oxalates, etc., in the diet (particularly when the source is from plants) is incorrect, a byproduct of an incorrect deduction that because the stones are oxalate that therefore all foods high in oxalate should not be liberally eaten. It has been 30 years since my last stone episode.

    2. I’d be dead now if that were the case, if not only due to stroking out from the pain of all the stones I should have gotten. In the contrary—healthier than I’ve ever been in my life from al these oxolate-containing foods.

  2. Wow, this is fascinating. I am enjoying every two seconds.

    I am intentionally saying two seconds because I am having to pause every two seconds and then back up.

    I realized that the translation at the bottom and the other words are warring with the text and if I don’t pause and read the whole sentence and back up and listen again, I miss the sentences.

    Years and years and years ago, I did Nutrisystem and they did an experiment where two people had to speak at the same time and you had to tell what they were saying and you can’t.

    A few of your newer videos have MRI imagery or other simple charts, but this one is exhausting.

    Maybe because it is also such a new concept.

    1. Laughing. It is that the translation box covers the text box when there is a long text box and then when I move the translation box, I find out that you aren’t reading the text exactly, so I have two sentences going on at the same time and have to start over.

    2. I did a Nutrisystem in OKC in one night (wall painting) a few decades ago. Either working at night or the volume of work (or both) threw my lower back out. I managed to get my industrial spray rig and all the tarping back in my van. I wrapped duct tape around my waist so I could sit up in my drivers seat. I pointed my van south and headed home.
      I crawled from my van to my house and up the stairs and laid in bed for over a day. I’m not a fan of night work. The zombies can have it.

      1. Dan,

        I have worked the night shift for years because that is when I function the best and because when I have tried to sleep, I have ended up being wide awake all night and had the most trouble focusing in the morning.

        My 90-year old relatives have the same problem.

        I took a high dose of Vitamin D the other day and I have slept 3 nights in a row.

        I am trying to turn this all around.

        It is so hard to do the meal timing without fixing the sleep timing.

        1. The short winter days goof me up. I take naps during the day. When I go to the gym it can be hard to get a spark going. Kind of like slow motion on the exercise bike and wanting to go to the kumbaya room (no such place–darn) and take a nap. I may be beginning stage Parkinson’s anyway. With long, hot summer days I do better. Last winter I discovered that pushing calories (10 lb. bags of potatoes) helped my comfort level and kept my energy up. I buy two or three bags of bread at a time and slather it with peanut butter to keep my weight up. I carry jars of peanuts with me in case my fuel runs short.

    3. I admit that I am still distracted by the new video format where Dr Greger is seen on the left side of the screen while the papers are shown on the right side of the screen. Dr. Greger – you are very distracting! (But in a good way).

      Concerning the info in this video, my colon agrees: On days I don’t sleep well (for which I blame mostly EMFs, and now esp. 5G), my colon’s output is delayed for hours; depending on the sleep quality this can mean the occasional uncomfortable day without elimination.

  3. This is a fantastic series. I have two questions for the NF volunteers though – First, I read through the sources listed, but couldn’t find a reference for fasting a day impacting cholesterol by up to 95%. (i haven’t noticed that effect on my lipid tests!)

    Secondly, If we wake in the middle of the night and turn on the cell phone even briefly, is that light enough to disrupt rhythms? Thanks!

    1. Dunno. I get up several times a night to go to the bathroom. If I leave the lights off I seem to be able to get back to sleep easier. I like the image of the brain at the top. I’ve not seen the eyeballs like that before. I thought the optic nerves went to the back of the brain, instead of just the middle. I did not know the junction of these nerves have a time clock node sitting on top.

        1. Thanks, it does seem like nerve ganglia (?) come off the back side of the optic nerves and wrap to the back of the brain. Several years ago Nova did a program on vision showing that vision is not just processed in the back of the brain but in as many as eight other places. This back up or redundancy (holograph) is maybe why stroke patients can sometimes recover brain function.

    2. My doctors have always required a fasting blood test because it affects lipid levels. The requirement is from midnight prior to the test. I usually get at least a 12 hour fast. Have you done a 24 hour fast prior to lipid testing?
      Yes, from what I have read, any blast of bright light can disrupt your rhythm for sleep from what I have read.

      1. Roger Nehring, ty for your comments. I have to do fasting lipid panels too , usually fasting somewhere between 12 and 14 hr by the time I get through the morning line-up at the lab. The reason why I am interested in fasting vs cholesterol question is this. The ONLY time my (high) cholesterol appreciably lowers is while I am losing weight. This does not happen often since I am bmi 19. Then the cholesterol slowly climbs back up to where it was. I did check levels in hospital, fasting 24 hrs, and it went up. I went to check Dr Fung’s pages on the question of fasting effects on cholesterol.. For example, here https://www.dietdoctor.com/fasting-and-cholesterol
        But also check the comments below of the people saying their cholesterol did NOT go down, it went up!

        Also, this page is interesting describing what happens during a fast and cholesterol levels rise https://www.mdmag.com/journals/internal-medicine-world-report/2011/summer2011/cholesterol-levels-rise-after-a-24-hour-fast They were investigating the possible idea of fasting having positive effects for those with cvd.

        Re the light at night , I suspect that you are right. All the sleep hygiene articles I have read say to keep the room dark, and even face the alarm clock the other way so maybe even minimal flashes are enough to raise cortisol.
        Just have to experiment more!

          1. Thank you Dan Cagle! Excellent link about using our devices before trying to sleep. Could be a tough habit to break, but I’ll give it a go. :)

        1. Isn’t lipolysis common during fasting?

          In other words, fat stores are broken down. I would imagine that this involves releasing various lipids including cholesterol into the blood stream and this would artificially inflate various lipid measurements in blood tests. It probably wouldn’t make much difference in short overnight fasts but might be noticeable in longer (24+ hour) fasts.

          In fact I understand that fasting is no longer required for cholesterol blood tests (although it is still required for glucose testing).

    1. I am wondering if there is going to be a video on the same concept with leptin.

      The leptin rhythm was altered by meal timing in a manner very similar to the rhythm of de novo cholesterol synthesis.

      There are so many factors. I am succeeding at eating breakfast, though not at 8 yet.

      I will be honest that since I started working so hard at eating breakfast, I gained 2 pounds.

      I am hoping now that I am sleeping at night, I will figure it out, but this whole process has been excruciating.

      I am staying highly motivated by these videos and by Chef AJ’s Summit.

      Most of the speakers acknowledged that some people have it so much harder than other people.

      I was really moved yesterday when Dr. McMacken shared walking a homeless man who was eating at homeless shelters through the process. She said that once he got a place to live he started succeeding. Ryan from Happy Healthy Vegan also brought up the “housing first” concept. I am trying to walk my friend who is in her mid-sixties who was homeless 2 years ago through it. Anyway, I started tearing up that Ryan and that doctor understood.

      1. Deb, I thought it was interesting in Chef AJ’s summit when Dr. Klapper said weight gain happens when sugar and fat are eaten at the same time–and that the sugar is used immediately while the fat is stored. He said for that reason not to eat bread and say, peanut butter….

  4. I would think this could be life-changing for some teens, especially with adhd, behavioral, bi-polar disorders. Maybe its not just because they’re a certain age.
    Not to mention everyone else skipping meals like me, night shift workers, and business travelers, etc.

  5. I am a breakfast skipper, but I only eat two meals a day – 12:00 noon and 6:00. I often snack on fruit at 10:30 am. Am I stepping out of “circadian” bounds?

  6. I was just listening to Chef AJ’s summit and commenters were talking about how they had gotten counseling from the official organizations for Diabetes and how their parents were on diets their doctor told them to do and I started tearing up, but I also truly feel such gratitude for all of these “internet doctors” and for people like John and Ocean Robbins and Chef AJ and all of these free online Summits. There is so much information online and all someone has to do is stumble over one gateway doctor or blogger and they can hit the motherload of information.

    I feel like I really will help people at the Senior Center near me even just find the “internet doctors” and talk them through what to do when every single person in their lives wants to argue with them because of it.

  7. My cousin has spent decades meeting with nutritionists, on top of meeting with doctors/specialists and reading resources from various organizations and not one of them has told him any of it.

    1. Good question! I’d like to know that too. Is eating at 10:00 am really worse than eating at 8:00am? We’ve seen studies showing 1pm lunch is better than a 4:30 pm lunch, but I don’t recall any studies comparing different breakfast times.

  8. I’d love to see a video on Deflour Your Diet. What do you mean by intact grain? Is that just whole grains? What do you mean by powdering? Is that just grains like in children’s cereal? Thanks for all this invaluable information!

    1. Intact grain has NOT been made into flour. Intact grains include wheat berries, spelt berries, brown rice. quinoa, millet etc. I assume powdering means turning a whole intact grain into flour. So whole wheat bread is NOT an intact grain.

    2. Hi, allison! I will pass along your request, but Dr. Greger is generally too busy reading medical journals to comment on every diet book that comes along. Intact grain means the whole grain that has not been cut or ground. Flour is grain that is ground to a powder, and may be refined by having the bran removed, along with all the nutrients included, as well as possibly bleached. After processing most of the nutrition out of grains to make flours, manufacturers then “enrich” them by adding vitamins to replace the ones removed in processing. It is generally accepted that intact whole grains are best for health. I hope that helps!

  9. The questions above strongly resonate with my own. Can you reconcile the positive health impacts of a time restricted diet (for example, an eating window from 12 noon to 8pm) with recommendations to making breakfast a key meal in the day?

    1. Malcom,

      Dr. Greger has videos on time-restricted eating and on skipping breakfast.

      When you look up the studies on skipping breakfast as a form of intermittent fasting, the statistics are really bad. All-cause mortality bad.

      The video from last Wednesday is the one to watch about how eating at different times affects things like insulin resistance. If you eat the same food in the morning, it might only spike blood sugar a little bit where eating it at night you can go into diabetic blood sugar range from the exact same food.

  10. What else drives our peripheral clocks besides food intake? I’m wondering if exercise would. You’d think a hard running and weight lifting session might clue the body in that it is daytime and we are no longer sleeping. Lots of metabolic changes occur during exercise.

    1. Julie,

      As an airline pilot I do shift work across time zones and skip nights with only two 90 min. naps on ten to twelve hour flights. I find exercise a very valuable tool to ‘adjust’ my internal clock. I use it in situations when I want to delay going to sleep to a more convenient time. For example when I arrive somewhere (exhausted) in the afternoon on an eastbound flight, going to sleep right away will result in waking up hungry in the middle of the night because you missed dinner and it is nowhere near breakfast time. When I do a 30 min. run and some sit-ups/push-ups instead, after I finished my shower I feel energized again, just long enough to make it to dinner time. Then I crash and sleep 8-12 hours to recover and wake up for the local daytime.

      On a westbound flight I often find myself awake very early in the morning. That is a situation where I read a book and then exercise early before breakfast that works very well for me.

      So exercise helps me temporarily shift my clock to an unnatural time zone.

  11. Yes, I get up for work at midnight and work driving and making delivers till 1-2:00 p.m., then to bed at 5:00 p.m. I do this 4 day a week. The other 3 I usually go to bed around 7:00 p.m.and stay in bed till 5:00 a.m. I’m usually really tired on work days. and less enthusiastic on my days off. I’m hoping Dr Greger has some advice for me.
    Thanks,
    Magdy

    1. Magdy,

      Yes, shift work is so hard.

      The thing that just came to mind though is that my grandmother was a rotating shift worker. A nurse. She would go on from 3 to 11 and they would ask her to stay the night shift and two days later she would be going in early in the morning.

      What occurs to me is that she was a highly disciplined person and was someone who would sometimes be the only nurse who got to the hospital on time in a snowstorm even though she had a half-hour drive to get to the hospital.

      But she lived into her nineties and didn’t really need medicines until the end and wasn’t on much. Lasix as needed.

      Thinking about her comforted me because I know that he has a night shift consequences video but she didn’t have any of it and that is likely to be the bowl of fruit on her table and the veggies in her fridge.

    2. Hi, Magdy El-Badry! Working night shift does disrupt our circadian clocks. You can find everything on this site related to chronobiology here: https://nutritionfacts.org/topics/chronobiology/ A whole food, plant-based diet may improve melatonin levels. More on that here: https://nutritionfacts.org/topics/melatonin/ The best thing, if possible, would be to switch to daytime work. Meanwhile, I hope that helps!

  12. More on this: https://www.gq.com/story/it-matters-when-you-eat?mbid=synd_yahoo_rss

    “But this wisdom isn’t necessarily new: the idea that one should “eat breakfast like a king, lunch like a queen, and dinner like a pauper” has been around in some form for centuries.”

    I always wonder what they mean by “dinner like a pauper.” How much does a pauper scarf down? Not much, I don’t think. All three of my squares are pretty much evenly divided in the *burp* area. In other words, I’m not one of those who can walk away from a meal only 80% filled. (How do you measure something like that?) Isn’t that what’s suggested somewhere? But as I’ve posted before, I’m on the lean side and I don’t eat between meals.

    1. YR,

      You probably don’t have the blood sugar spikes and insulin issues.

      I have been listening to Chef AJ’s summit this week and I ended up eating a whole lot of baby potatoes for dinner and I get hungry every time I eat potatoes and tonight was no different. Two hours later, I was seriously hungry and ended up having a dessert after 7.

      I thought about it after and I might be able to eat potatoes for breakfast or lunch.

      Maybe that wouldn’t spike as much and I might not have the hunger rebound.

      I am not sure.

      I just listened to all of the people who can eat potatoes and just decided to try it again, thinking, “If I get hungry, I will just ride it out and try to sleep, since I am sleeping better” but I ended up having a Lara Bar.

      That is my junk food and I try not to eat it and don’t have cravings except when I eat potatoes for dinner.

      I might try them for lunch someday and see if I can eat them for lunch of if they are just impossible for me.

        1. Liisa,

          Yes, I usually do eat beans and sweet potatoes and carrots and some greens with potatoes in a stew, but, still I think even then, white potatoes cause a glycemic reaction.

          Every once in a while I try them, and I think listening to Chef AJ caused me to want to try them again.

          I mostly eat individual foods, except when I have food prep time.

          This week, I ate Ezekiel english muffins with powdered peanut butter and a piece of fruit for breakfast. Another 2 pieces of fruit and salad with mushrooms and pomegranate seeds and no oil hummus for lunch. It tends to be, then grab a kiwi or carrots. Then, something simple for dinner. Rice or pasta or sweet potatoes or beans.

          When I have time, I do something like chili or a stew or a casserole, but this past weekend was busy and I have also been listening to Chef AJ’s conference, so I just haven’t had time for meal prep.

  13. Deb, who says you have to eat potatoes? Is that all you ate in a meal, just a bunch of white potatoes? Despite what the spud guru says (Dr. McD.), there are other foods out there. Like sweet potatoes. Personally, I’d certainly want a variety of yummies at a meal.

    And your meals should be tasty and enjoyable!

    1. YR,

      When I have time, they are tasty and enjoyable. When I am listening to a conference all week, plus working, they are probably more likely to be quick and easy.

      1. The Krocks are doing a potato-centered Mary’s Mini and Cyrus was talking about tests with sugar water and was talking about Kempner and Diabetes.

        I felt like I should be able to do it.

        I can eat just rice and not have any glycemic response, even when I have eaten it later at night.

        Whenever I eat potatoes, I end up feeling hungry and craving sugar.

        That is just the way it is.

        But it is fascinating that I can eat just rice and not potatoes by themselves.

        1. Deb, you aren’t the only person that happens to. I remember posting the link from Dr Mirkin warning that for some people higher glycemic whole foods can cause cravings… like potatoes. I tried to eat them but gave up. I am pretty sick of sweet potatoes now, but you might find winter squash to be tasty and filling. I bake cubes of it and throw it on a salad.

            1. Barb,

              Yes, I remember you posting the Mirkin post.

              I get sick of sweet potatoes sometimes, too.

              I realized this morning that, no matter what, if I do eat potatoes, from now on it will be for lunch.

              If I get hungry a few hours later, it will be dinner anyway.

              1. I was listening to Dr. Klaper this morning and I think he just changed my eating combinations.

                He was talking about the fat and sugar combinations and said things like if you eat tahini, don’t pour it on a potato. The body will burn the sugars in the carbs and will store the fat. Or if you had almond butter and a jam on bread it would burn the sugars in the bread and fruit and would store the almond butter, so don’t eat it at the same meal.

                I don’t do those exact combinations, but clearly I am not losing weight and there are so few things I am eating that it has to be the way foods are combined and the timing.

                I just slept for the 4th night in a row since I took the extra Vitamin D and I have been eating breakfast since this series started, but I am still not losing weight and Dr. Barnard said that, “Nope, even if you lose inches, if you don’t lose pounds something is wrong.” in his interview, so I have to ditch the hummus eventually. Sigh. I like the hummus, but unless I eat it with a spoon, it goes on a carb.

  14. I may have missed something, but my question involves fasting; maybe for 24 to 36 hours. How might this influence the bodily rhythms ? I work nightshift: overweight, high blood pressure, sleep during the day !

  15. I’m going to have to watch this video another two or three times, take some notes. That’s a lot of information to pack into one video. I feel like I’m staring at a can of orange juice because it says ‘Concentrate’.

  16. So taking all those circadian rhythm and food intake studies into account is there any advice for what to do when you fly into a different time zone?
    Should we keep our body on our time bu eating in the middle of the night for example or should we adapt to the new time zone as soon as possible.

    1. Roger,

      Tom posted that recently and he mentioned that it was a general population study and that they said that the people who had high levels of B-12 also had higher BMI and higher blood pressure.

      Meaning that they weren’t vegans supplementing B-12. They were more likely to be eating a lot of animal products.

    2. Roger, I posted my test results 2 days ago and I had way too high b12. I tried daily 1000 ug…. wayyyyy too much. t2 x per week, still way too much. I chisled a piece off a tablet every day and it came back 700. too much.
      All other tests for kidney, liver etc were great. So my doc said, don’t take any b12. There will be a small amount in the iron pill I have to take now. We shall see in about 12 weeks how it goes.

  17. How do you suppose intermittent fasting (IF) affects these biorhythms. For example, I eat between 12 Noon and 7 pm. Considering the many and profound beneficial effects of IF, this news is less than pleasing.

    1. I didn’t notice anything profound about intermittent fasting in the research shown here and it wasn’t compared to WFPB diets or tested on subjects eating WFPB diets. Anyway, you still stop eating at 7pm so it doesn’t like too much of an issue to me.

  18. Dr. Greger addresses this topic in a previous video. “So, if you’re going to skip any meal, whether practicing intermittent fasting or time-restricted feeding (where you try to fit all your food into a certain daily time window), it would be safer and more effective perhaps to skip dinner rather than breakfast.”
    https://nutritionfacts.org/video/how-circadian-rhythms-affect-blood-sugar-levels/ (at 5:16)

    Keep reaping the benefits of intermittent fasting with the benefits of eating earlier, by consuming your food earlier in the day.

  19. Does anybody have an enameled Dutch Oven?

    I saw a recipe that I wanted to try but they cooked it in a Dutch Oven.

    I did my America’s Test Kitchen process and they said that Le Creuset of a certain size is the one they always recommend, but that it costs almost $400. I found one of the exact ones they said for less than $90 on a site that takes Paypal. (Amazon is selling the same one for $399.) I went back and forth and back and forth and back and forth and unless they are knockoffs, it says Le Creuset.

    I know that they are heavy and I don’t need the size they said, but that is such a good price that I paused.

    Is enamel toxic?

    I get exhausted from trying to figure everything out.

      1. According to Le Creuset, their products are tested and found to be in compliance with California Proposition 65 standards, and I found an independent testing place that tested for things like lead and cadmium and it came out clean.

        So, is it stolen or is it a steal or is it a knock-off that it is over $300 cheaper?

        I guess it could be a seconds with some enamel-damage or something.

            1. Ohhhh wait Deb, S is right. The 1 star reviews show the enamel cracking etc. That shouldn’t happen. le creuset are pretty tough (and heavy!) , and although amazon’s are only a fraction of the cost, you don’t want to throw away money regardless.

              1. Thanks, Barb.

                I dug a little into the company selling the very cheap Le Creuset and guess where the company is. China.

                That caused me to dig a little deeper to see if they make things in China (which is notorious for copying designs and selling them) Currently, all Le Creuset cast iron is still manufactured in the company’s foundry in Fresnoy-le-Grand but products that are not cast-iron may be made in other countries, such as China (accessories or silicone products), Thailand (kettles and ceramics), England (enamel cleaner), Portugal (stainless steel) and Swaziland (clay pots) Wikipedia has a “citation needed next to Portugal” but more than one place mentioned China and Thailand.

    1. Deb, no idea about enamel—good question—but be careful of third party sellers and things at suspiciously low prices. There is in fact a very real issue with counterfeit products out there. Sometimes it’s better to just invest in the real deal and know what you’re getting rather than getting off Amazon or strange websites for the lowest cost you can find.

        1. The concept that the fake Le Creuset was likely made in China switches it to is there LEAD in it with all-caps LEAD, so I guess us internet novices will get fooled over and over and over again.

              1. Le Creuset doesn’t sell “seconds” they have 15 people check them for flaws and if they don’t pass that check, they re-melt them down is what they said.

                There are 70 outlet stores that sell discontinued colors and things like that, so there are opportunities to get good sales.

                But probably not from a company with a name in Chinese lettering.

                1. Oh, no way stay away from China-based sites! I mean I once got a good Halloween costume from a business/site that was out of China, but it was a well known company with real people who contacted you, etc. I also made a purchase of an item on another and never received it… the whole thing was fake, but I obviously got that knocked off my card. But yeah I also read that most counterfeit comes from China. And what websites will do when they sell fake stuff (not all from China, third party sellers on Amazon from anywhere do this) is post the photo of the real product. I had to send fake pajamas back to a counterfeit seller on Amazon. So buy only from the actual company (so if I get on Amazon I get from the company actually selling it on Amazon) or reputable businesses who sell their products.

                  Sounds like the discontinued colors and such is a great deal! That’s cool you can find that.

  20. This seems to imply that a fasting blood test for blood lipids will produce poorer numbers than for the same person eating breakfast.

  21. All this clock talk is starting to sync (sic) in. All of our organs, intestines, fat and even poop have their own circadian clocks. Things like dawn sunlight and a breakfast meal help sync the clocks together. If one does not get a good nights sleep or is practicing poor nutrition or jet lagging (add numerous other things here), our bodies are not synchronized.

  22. I have a question. My bedroom is not completely dark. I can definitely see across the room, clearly. Can I just wear an eye mask? Or for some reason do the cells in my body detect the light in the room? Does the room have to have a complete black out or just my eyes? Sounds like a stupid question but I got to ask before I buy an eye mask or blinds.

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