Episode 41: When to Eat

When we eat may be just as important as what we eat for managing obesity and health. We talk to Dr Gerda Pot, Nutritionist from the Louis Bolk Instituut and Kings College London about the emerging field of chrono-nutrition.

Dr Moira Junge (Health Psychologist) and Dr David Cunnington (Sleep Physician) host the monthly podcast, Sleep Talk, talking all things sleep.

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Audio Timeline / Chapters:

  • 00:00 – 02:25 Introduction
  • 02:25 – 20:13 Theme – When to eat
  • 20:13 – 20:57 Clinical Tip
  • 20:57 – 22:23 Pick of the Month
  • 22:23 – 23:51 What’s Coming Up?

Next episode: What to eat

Links mentioned in the podcast: 


Guest interviews:

Dr Gerda Pot

Dr Gerda Pot is an experienced Nutritional Scientist and lecturer working at Louis Bolk Institute in The Netherlands, and King’s College London. Dr Pot is skilled in Epidemiology, Lecturing, Scientific Writing, Clinical Research, and Life Sciences and has a Postgraduate certificate in Academic Practice in Higher Education from King’s College London.Dr Pot’s recent research has been in the effects of the timing of food intake on health including sleep and obesity.Dr Pot has recently published data from a pilot study of a nutrition and lifestyle intervention in type 2 diabetes showing improved glucose control and reduction in glucose lowering medication. You can find more links to Dr Pot’s research here. Dr Pot also appears regularly in the media promoting healthy eating and outlining the impact of chrono-nutrition, such as in this article for New Scientist, and this piece for Dutch television.

Regular hosts:

Dr Moira JungeDr Moira Junge is a health psychologist working in the sleep field, who has considerable experience working with people with sleeping difficulties in a multidisciplinary practice using a team-based approach. Moira is actively involved with the Australasian Sleep Association (ASA) and a board member of the Sleep Health Foundation. She has presented numerous workshops for psychologists and is involved with Monash University with teaching and supervision commitments. She is one of the founders and clinic directors at Yarraville Health Group which was established in 1998. In addition to her expertise in sleep disorders, her other areas of interest and expertise include smoking cessation, psychological adjustment to chronic illness, and grief and loss issues.


Dr David CunningtonDr David Cunnington is a sleep physician and director of Melbourne Sleep Disorders Centre, and co-founder and contributor to SleepHub. David trained in sleep medicine both in Australia and in the United States, at Harvard Medical School, and is certified as both an International Sleep Medicine Specialist and International Behavioural Sleep Medicine Specialist. David’s clinical practice covers all areas of sleep medicine and he is actively involved in training health professionals in sleep. David is a regular media commentator on sleep, both in traditional media and social media. David’s recent research has been in the area of non-drug, psychologically-based treatments such as cognitive behavioral therapy and mindfulness in managing insomnia, restless legs syndrome and other sleep disorders.

Connect with David on Twitter or Facebook.

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Intro: Welcome to Sleep Talk, the podcast developed all things sleep brought to you by SleepHub.com.au. Here are your hosts, Dr. David Cunnington and Dr. Moira Junge.

Dr. David Cunnington: Welcome again and welcome Moira.

Dr. Dr. Moira Junge: Hello, Dave. Hello, everyone.

Dr. David Cunnington: So this is Episode 41 of Sleep Talk, the podcast talking all things sleep. And the theme for this month’s podcast is when to eat, trying to get our heads around is there an impact on what time of the day we eat and how that relates both to sleep and longer term health outcomes. And as you will hear, we interview Dr. Gerda Pot who is one of the recognized experts in this area.

So what has been going on for you, Moira?

Dr. Moira Junge: Oh, nothing much actually. I’m sleeping a lot. It is winter hibernation trying to get really good quality sleep and trying to look after myself. I don’t have any gossip or anything exciting to tell. What about you in the sleep world?

Dr. David Cunnington: I don’t hibernate to quite the same extent that you do. That’s not my usual pattern. One of the things that has come up a bit lately is sharing a bed with someone and how does that impact on sleep. And the media picked up on that lightly and I did a piece for the Sleep Health Foundation.

Dr. Moira Junge: Yes. Thank you for that. Very cool to portray.

Dr. David Cunnington: Yeah. I felt a bit like I was sort of in enemy territory or at least out of my comfort zone.

Dr. Moira Junge: Out of your depth. Do you have your cardigan or a leather jacket?

Dr. David Cunnington: Yeah, I was decidedly uncool. Not quite rocking the cool factor. But it was a really good interview and I have had some good feedback from a number of people about just talking through that issue about how you go actually trying to sleep in the same bed with someone else.

Dr. Moira Junge: Yeah. Well, it’s a common – it’s not uncommon, is it? In our world, it’s not uncommon. It’s something that people talk about quite a bit. And not even with your romantic partner but even say, like sleepovers and things like that, school camp, people say, “I can’t sleep with people in the room, let alone in the bed.” So that’s something we will explore in another episode.

Dr. David Cunnington: Yeah, it would be a good topic for us to explore. And it is a trigger sometimes for people to come and see us in consultation. They can manage sleep themselves if it’s just them but once there’s someone else, that’s the straw that breaks the camel’s back. It drives them to come and seek help.

Dr. Moira Junge: Yeah, that’s a bit of a topic because I did something in April. We can put a link to that.

Dr. David Cunnington: So the theme for this month’s podcast is when to eat. And it’s actually got a fancy name, it’s called Chrono-nutrition. For many years in the diet world it has all been about what we eat, counting calories, the food pyramid, proteins, carbohydrates, Paleo diet, Pritikin diet. But even some of those fad diets are starting to incorporate these concepts around timing. A number of patients now talk to us about the 5:2 diet, fast for 5, eat for 2. That has got that concept of …

Dr. Moira Junge: Surely, fast for 5.

Dr. David Cunnington: Yeah, thank you. You see how familiar I am with this concept. There has definitely been research coming out in the basic science literature about time-restricted eating. Someone who is a well-known author in this area has been Satchin Panda, publishing data on restricted eating within say, an 8-hour window, there is reduced rate of obesity at least in animal models, not yet really demonstrated in human models.

And so we thought we would try and explore what are healthy timing or a healthy consideration around the timing of meals. So to do that, we interviewed Dr. Gerda Pot. Dr. Pot is a nutritional scientist and lecturer working at Louis Bolk Instituut in the Netherlands and King’s College in London.

So thanks very much for helping us out on the podcast, Gerda.

Dr. Gerda Pot: Thank you, David, for inviting me.

Dr. David Cunnington: No problem. So what actually is Chrono-nutrition?

Dr. Gerda Pot: Chrono-nutrition is a term that was parsed in 1986 by a French researcher and it’s about study of not only what we eat but also when we eat and how this affects our health. So it’s about studying the impact of timing of eating. And when you think of time, I look at three elements there. There is clock time, frequency, and irregularity. It’s also very closely related to research on sleep and both sleep and dietary intakes have the biological clock as underlying mechanisms.

Dr. David Cunnington: So how did you get interested in this area of Chrono-nutrition?

Dr. Gerda Pot: The reason I got interested in this topic is that I have a grandmother who reached the age of 97 in very good health and the reason why I want to figure out what her secret was. So I noticed when I spent time with her, she had a very regular meal pattern. She had breakfast every day at the same time, lunch at the same time, dinner at the same time. And I really wondered whether this could be the secret to her reaching a healthy age.

And so I thought of investigating this and I actually found out that not many nutritionists have looked at this topic in detail.

Dr. David Cunnington: So recently, a new evidence in the literature that when we eat impacts on health risk.

Dr. Gerda Pot: There is. And the evidence is on three things. So far, most of the evidence comes from observational studies. So if you think about for example, studies in shift workers, studies have observed that they have an increased risk of developing chronic diseases such as cancer, cardiovascular disease, and metabolic syndrome.

There are few studies that have been published so that regular meals could be important for our health. But of course, observational studies do not infer causality so we need clinical trials to confirm that. And in that area, a few studies have been published and they look mainly at the effects of regular meal frequency and they were performed on a small scale. So there was a study done in 9 healthy lean women and another study which was comparable in 10 healthy obese women. And these were randomized crossover dietary intervention studies and they investigated the impact of irregular meal frequency pattern on a number of health outcomes including circulating lipids, insulin, glucose, and so on. In the meantime, both these studies reflect an irregular eating frequency seem to negatively impact fats and lipids and insulin profiles confirming the importance of mael patterns in influencing carbohydrates and lipids metabolism in addition to the amount and of course composition also of what people eat.

Dr. David Cunnington: How do you think that some of the negative metabolic effects of Chrono-nutrition with timing of food might be mediated?

Dr. Gerda Pot: I think this comes down to internal body clock for many nutritional metabolic processes actually also the circadian rhythm. So think about for example appetite but also metabolism of glucose and cholesterol and when you eat at the normal time for your internal clock this can have a negative impact on your health.

Dr. David Cunnington: We certainly see lots of other negative impacts on health in both shift workers and people that eat irregularly. What about data on the irregularity of meals?

Dr. Gerda Pot: I think for your internal body clock, it’s also important to ask periods of non-consumption. So for our body clock to work at its best, we also need time of rest in certain organs. So then not eating all the time actually benefits your internal body clock.

Dr. David Cunnington: There’s that data out of Satchin Panda’s lab on time-restricted eating. Has any of that been born out in other work you’ve done or some of the literature you’ve reviewed?

Dr. Gerda Pot: It’s actually very closely related because both Satchin Panda and I see that the body needs a period of non-consumption. So in their work in the time-restricted feeding work it has gone to a more extreme so restriction to certain hours. I think if you stick to three main meals, it allows your body to have enough time with non-consumption to allow your body clock to work at its best.

Dr. David Cunnington: So what is it about that period of non-consumption that you think allows the body clock to work best and seems to be healthier from a metabolic and nutritional point of view?

Dr. Gerda Pot: So biologically speaking, a biological clock is not exactly 24 hours. The body clock needs some cues to reset to 24 hours again. So one main element of that is light of course, but the other one is dietary intake. So if you restrict your dietary intake to specific periods of time so not eating all the time that actually helps to reset the clock.

Dr. David Cunnington: Yes. And we often talk about light or in the sleep field, we think light is the main zeitgeber or synchronizing signal for the circadian rhythm. And I think we underplay the effect that meals have and I think that’s a bit of a blind spot for us often in the field.

Dr. Gerda Pot: Yes. I think it’s a combination. So I do think light is the main zeitgeber but I think dietary intake is another important one.

Dr. David Cunnington: People that I see or if I look at media articles about sleep or if people are trying to improve their sleep, they may be careful about light but really meal isn’t on the radar for them. So are there any intervention studies advising us or giving people sort of guidance in terms of if they follow a regular meal pattern that it does make any difference to their metabolism?

Dr. Gerda Pot: So if you specifically refer to sleep, I think that’s the study I would really like to do next. The group I work with at King’s College, we actually did the reverse. So we looked at people who have chronic sleep deprivation so they sleep less 6 hours a day and we wanted to know whether we could make them sleep longer and how that impacted their dietary intake. So we did a feasibility study and we gave advice on how to improve and then how to do extend their duration and we actually managed to make people sleep about 30 minutes longer and we found that their dietary intake is somewhat changed and their carbohydrate intake for example decreased.

We know from studies that when people are sleep deprived they choose different foods. So they eat more carbohydrates and more fats. And yeah, you can think of ways to reverse that and use dietary patterns to change their sleep again.

Dr. David Cunnington: How are you proposing to do that? If you had unlimited budget and someone just said, “Just design the study you want to do,” how would you look at that?

Dr. Gerda Pot: I would prefer a randomized controlled trial where one of the group would be allowed to define their own regular meal pattern so that actually suits them and their biological clock and the goal is to let them eat three regular meals a day and to be healthy of course and use fresh and unprocessed foods. Then I will have the control group where I just let them carry on as they were and then compare the impact on sleep and also on their other metabolic health outcomes. For example, blood pressure or glucose level or cholesterol level.

Dr. David Cunnington: And then you reviewed the literature and published that great paper in 2016. Based on that, what have you been working on lately to try and move the field forward?

Dr. Gerda Pot: So now, that would be more practice-based research. So at the moment, we’ve just published a pilot study on a lifestyle intervention program including nutrition and including the message that people should consume three main meals a day. And this was in type 2 diabetes patients and we found that people who follow this lifestyle intervention program for 6 months could reduce their medication use and improve their type 2 diabetes.

Dr. David Cunnington: That’s your pilot data. Where does it go from there?

Dr. Gerda Pot: So we are actually doing a main study now. We are trying to include 1900 type 2 diabetic patients and then evaluate the effects after 6 months. But also, more long term because the program, it’s meant to make real lifestyle intervention which can actually be prolonged. So we also want to look further after 18 months and also 24 months.

Dr. David Cunnington: There has been increasing work and you wrote that lovely review in 2016 about the impact of timing of feeding and the impact on health including sleep. Are we ready for primetime? Is this a message we are ready to roll out in a public health sense or there are still missing pieces?

Dr. Gerda Pot: I think that’s a very good question. I think we are almost there. But I think there are, as you say, a few missing pieces. I think chrono-nutrition should be part of a bigger picture. So if you were to perform a lifestyle intervention study, this is one element but it should be considered as part of the bigger picture.

There are actually countries out there like Sweden that have incorporated chrono-nutrition in their dietary recommendations. But I think we need a little bit more research before we are there.

Dr. David Cunnington: And there are existing stakeholders. There’s a whole industry that tells us what we eat is the key to health. If you try to roll out these messages about when we eat being important, how have you gone with that in a public health sense? Are there barriers or any resistance to that message?

Dr. Gerda Pot: Yeah, also very good question. I think if we think about public health, and yes, we all want to improve people’s health so if this is one element we can use, one modifiable risk factor then I think we should definitely try to investigate it.

And what I see is that generally, that message has been received well because people can easily grasp its concept and then refer it our common sense. However, when we think about for example industry, who are trying to sell out more snacks and perhaps maybe for them, not so beneficial.

Dr. David Cunnington: And of people are looking to apply the principles of chrono-nutrition sort of based on what – from work that you’ve done and other groups have done. What do you suggest as suitable a way forward?

Dr. Gerda Pot: I think eat regularly. So, not too much variation in the time of day and from day to day. Eat of course healthily both fresh and unprocessed foods and allow your body to have sufficient time of non-consumption. So stick to the 3-main meals. As an example, my grandmother, she had a regular meal routing andwith that, she actually reached a really high age, she reached 97 and was in generally good health just before she passed away. And I think thiswas one of her secrets.

Dr. David Cunnington: It’s an interesting observation. I do some work with a health spa and I am fortunate enough to be able to go to the health spa periodically and spend some time there. One of the things that happen at the health spa is life is very regimented, breakfast today at 8AM, lunch at 1PM, dinner at 6PM. It’s the same every single day and it does seem to be important in that routine.

Dr. Gerda Pot: Yeah, exactly and I think that our grandmother or grandparents knew actually quite well how this works. And even if you go further back in history, I think it was already Hippocrates who talked about the importance of eating regularly.

Dr. David Cunnington: Great. Thanks very much, Gerda.

Dr. Gerda Pot: Yes. Thank you.

Dr. Moira Junge: Very interesting interview. Thanks, Dave. That was – that is so important that we are starting to talk about this issue because it has come up regarding timing ofmedication that has been spoken about at conferences. Obviously, it’s more focused now on timing of food.

Tell me your overall summary or your take home thoughts I guess after that really interesting interview.

Dr. David Cunnington: Yes. So I think the work Gerda Pot has been doing as well as other groups around the world, yeah, I’m now convinced that when we eat is at least as important as what we eat.

Dr. Moira Junge: Absolutely.

Dr. David Cunnington: With the passage of time we may actually find it’s more important than what we eat and that’s – how much would that shake up the whole diet nutrition industry? But in my personal practice, I’m going to have to be asking people, what time do you eat? Thinking about meal intake and food is one of those important cues or synchronizers of the circadian system and something that’s going to impact on the circadian system.

Dr. Moira Junge: We are focusing on the sleep history often on the sleep. Tell me about your sleep into bed, out of bed. Tell me what happens. But very, very rarely, tell me about your food, not just what they are eating but the timing of it as well.

Dr. David Cunnington: It’s pretty clear from some of the work that Dr. Pot talked about that food intake is an important synchronizer of the circadian system and if I’m trying to manage people’s circadian system and giving advice about light I should be giving them advice about meal timing in that as well.

The other stuff I really found fascinating and I don’t think it has been fully explored yet is the time-restricted eating data. Some of the data from Satchin Panda’s group but other groups around the world looking at time-restricted eating that is restricting the amount of time per 24 hours that people are eating even as harshly as a 6-hour window has significant impacts on obesity and metabolic health. What’s that about and how is that about and how does that interact with sleep and the circadian system?

Dr. Moira Junge: Have you followed that quite closely, Satchin Panda’s work?

Dr. David Cunnington: He is a bit of a pop star in this area so you tend to hear him a bit. He actually pops up a lot on sports performance podcasts.

Dr. Moira Junge: Of course, yeah.

Dr. David Cunnington: How to be a better you? You know those type of things. How to be more awesome. Not that I’m really into that. But I’m following this whole area of how does when we eat fit in with sleep and health. That’s where he pops up a bit.

Dr. Moira Junge: Because food and sleep and health, that’s why we started doing the series of trying to think about food and sleep and some podcast episodes. It has much – people often ask me much more about – not the timing of their food. Definitely it’s what should I or shouldn’t I eat to help me sleep better. And that’s something we don’t really have very good answers to in terms – I think the shift work people are doing fantastic work around the timing of night-time eating and what’s best for that.

But in general, the person who is just generally not sleeping well, I don’t think I’ve got a good body of evidence to talk to them about the actual food or drinks or supplements during the day.

Dr. David Cunnington: Great. So that’s what we are going to cover in the next episode, Moira, so we will be able to get to some of those questions. And so, that’s going to complement what we’ve talked about in this episode with thinking about when we eat, how to think about food in terms of how it relates to other behaviors such as activity, sleep and wake.

So if you are looking for more information on the topic of when we should eat and chrono-nutrition, there’s a number of Dr. Pot’s research articles and I really like the review article on chrono-nutrition that she wrote in 2016 and I’ll put the link to that in the show notes.

There is some of the work of Dr. Satchin Panda’s Lab that I will also link to. They’ve got an online site that’s called myCircadianClock. It’s a project where you can download an app, put in all this data and then the app will tell you when to do a whole lot of things. Because I’m interested, I downloaded the app and started to put all this data in but it got pretty tedious pretty quickly. I had to put in every single thing I was eating, drinking, and when. But the promise is, if you do that then it starts to actually tell you when you should be doing things and what you should be doing to optimize health. The payback for them is that collect heaps of data about what people are doing.

Dr. Moira Junge: Are they upfront about that?

Dr. David Cunnington: They’re really upfront about that and there was certainly a lot of data to put in but something that’s interesting if you’re interested in that area.

Dr. Moira Junge: That’s good.

Dr. David Cunnington: And what about your clinical tip of the month?

Dr. Moira Junge: My clinical tip would be based on all the discussions and your interview, I think the tip would be that all of us clinicians and researchers really, certainly need to be taking a clinical history of someone who is presenting and talking about any sleeping difficulties that you ask about the timing of their food. That’s the simple – that’s the tip.

Dr. David Cunnington: Not just, “Do you eat? When do you eat?”

Dr. Moira Junge: Yeah. But, “What is it?” And I’m very focused – I’ve always been focused much more to alcohol, caffeine, size, timing – not timing but just, “Are you eating regularly?” But yeah, so that’s my clinical tip.

And what about your pick of the month, Dave?

Dr. David Cunnington: Well, this is right back at you, Moira. So you sent me this. This was The IKEA Sleep Podcast.

Dr. Moira Junge: Oh, yes!

Dr. David Cunnington: You go to sleep listening to somebody reading out the names of IKEA products in Swedish.

Dr. Moira Junge: Did it work?

Dr. David Cunnington: Are you feeling sleepy yet?

Dr. Moira Junge: No, it just makes me laugh. [Laughs]

Dr. David Cunnington: So there you go.

Dr. Moira Junge: That’s your pick of the month?

Dr. David Cunnington: That is my pick of the month.

Dr. Moira Junge: With all your reading up with journals [Laughs]. That’s hilarious.

Dr. David Cunnington: So thank you for that tip, Moira. But what about for you?

Dr. Moira Junge: Well, my pick of the month is actually a podcast that has been done by Professor Harriet Hiscock and her team at the Murdoch Children’s Research Institute here in Melbourne, very generously have put together a series of podcasts very much focused on children sleep and parent issues and those sort of things, which is so fabulous, so overdue. And they’ve done it for – they made freely available. So we will put a link to that in our show notes. That’s my pick of the month.

So what’s coming up, Dave, in future episodes?

Dr. David Cunnington: So as we’ve talked about earlier, so the next episode is going to be about what to eat. So hopefully, it’s going to inform you and I that blind spot for us when people say, “What should I eat to sleep well?” Hopefully, I’ll be able to answer them after the next episode. And working up a couple of other episodes, so a research update about some of the latest from the Sleep 2019 Meeting and some other research, cannabinoids and sleep and their interaction with sleep and alcohol and sleep, and some other things that we are working up.

Dr. Moira Junge: Great. Good. Have we got our roving reporter, Simon Frankel, back for the update from the USA meeting?

Dr. David Cunnington: Absolutely.

Dr. Moira Junge: Yay!

Dr. David Cunnington: So look to having Simon back in a couple of episodes for that research update. So thanks for listening to the podcast. If you’ve got other suggestions for episodes, email us at Podcast@SleepHub.com.au. We are on Twitter now so we’ve got a Twitter handle @PodcastSleep. Send us a tweet or follow that to hear about the latest episodes.

Dr. Moira Junge: Fantastic. So thanks for listening and stay tune for next episode.

Outro:This podcast is not intended as a substitute for your own independent health professional’s advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider within your country or place of residency with any questions you may have regarding a medical condition.




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