Episode Transcript (Auto-Generated by Apple Podcasts Transcribe)
Welcome to Nutrition For Mortals, the podcast that says life is too damn short to spend your time and attention worrying about your food choices.
So let's take a deep breath, and then join us, two registered dietitians and friends, as we explore the world of nutrition with a special focus on cultivating a healthy and peaceful relationship with food.
My name is Matt Priven, and I am joined as always by my co-host and the best dietitian on planet Earth, Jen Baum.
Hey, Jen.
Hey, Matt.
And just a quick reminder, if you would like to support the show, we do have a Patreon where we do an extra bonus episode every month.
A portion of our Patreon does go to support the Hunger Project, which is a fabulous organization.
And we are real live dietitians in private practice.
And so if you or anyone you know has ever thought about working with a dietitian, you can always feel free to reach out to us on our website, oceansidenutrition.com.
Yes, you can.
Let's jump into this thing.
Matt, this is such a big topic.
I know.
I know.
This is a highly requested one.
We're talking about intermittent fasting today.
I know.
You've been living in the world of intermittent fasting for the last few weeks.
Intellectually, not physically.
A good distinction to make.
Otherwise known as the eating style of the bro in your office wearing a sleeveless puffer vest who doesn't have breakfast until 2 PM.
Well, you know what?
The other thing about this topic is that, I think, would you say that this is our most requested podcast topic?
Very possibly.
Yeah, it's up there.
It's up there.
And we've been a little hesitant to jump right into it because it's a little complex and nuanced, as I always say at the top of these episodes.
I feel like every topic we take on is dauntingly nuanced, and we want to do it justice, but we're going to try today.
Well, I would say too, if we're going to be very honest and pull back the curtain, I think we have started this episode.
I've started it at least twice and then stopped, and now you graciously decided to really dive into it.
And I'm very appreciative about that, because both times that I thought about doing this topic, I did get overwhelmed, because there is just so much to talk about.
Seriously, I mean, fasting alone could be like a two-part episode, and this is intermittent fasting, and there's multiple versions of intermittent fasting.
And so, yeah, we'll make sense of it today, I think.
I think I'm ready to talk about it.
That's awesome.
And so, aside from how requested this topic has been, why do you think it's important, or why should we dig into intermittent fasting?
Well, I think it's gone really mainstream, especially in the last couple years.
You know, like we have big health organizations repping intermittent fasting.
It's gotten this huge credibility boost, if you will.
It's not just for these like health optimization nuts online.
It's really like made its way down to the people.
We've got primary care doctors recommending it.
We've got medical schools writing articles about it.
And so, yeah, I think it's a pretty widespread topic, right?
No, for sure.
I mean, that's the shift that I've seen with intermittent fasting, is that I think at first, it came off as kind of more like fad diet.
But like you said, Matt, more and more we're seeing it recommended in clinical spaces.
And so I think that leaves a lot of people having a lot of questions about the benefits, or like the pros and cons of this type of eating style.
Yeah, and social media and podcasts have been huge for intermittent fasting.
I mean, there's so much content out there, both from like trusted health communicators, but also from just like clickbaity, you know, chiropractor turned content creator types, like your Eric Berg's, who are racking up millions of views with intermittent fasting content.
You see all sorts of thumbnails out there on YouTube about, I tried intermittent fasting for 90 days and look at me now.
And, you know, like it's just really like in the zeitgeist of health communications these days.
Yeah, for sure.
I mean, I think the other thing that happens on social media, too, is that there are just so many different versions of intermittent fasting presented, right?
You see things like only eat within a four-hour window or you can have an eight-hour window.
So I think it also leads to a lot of confusion around what intermittent fasting even should look like.
Yeah, I'm glad you're starting there, because I think that's something we really need to clear up is like, what the heck are we talking about here?
There's so many versions of intermittent fasting.
Yeah, I mean, I think that's a really probably important place to start.
I mean, how would you go about defining what exactly intermittent fasting is, given that you've been living in this space for the last few weeks?
Yeah.
Well, why don't I play a clip?
And I think this clip is speaking to how most people think about intermittent fasting and why they might pursue it.
And then we'll talk a little bit.
So this is Chris Pratt talking to Men's Health.
And this video is titled How Chris Pratt Transformed From Sitcom Star to Shredded Action Star.
Okay.
Love Chris Pratt.
“For me, actually, it was really about just kind of trying to trim body fat.
So I did something called intermittent fasting, and I ate from like noon to about 6 p.m.
That was my window to eat.
And what did I eat in that time?
Pretty much just healthy, boring stuff.”
He sounds so sad about that.
He does.
He does.
I side with Andy Dwyer, not modern Chris Pratt.
Yeah, yeah, yeah.
Yeah, same, same.
Andy's my favorite incarnation of Chris Pratt.
Yeah.
I would say sec...
I mean, for me, Guardians of the Galaxy, also one of my favorite roles of his.
Sure.
Absolutely.
He's talking about using intermittent fasting to lose body fat.
So that's the reason for approaching this, which it is for many people, which we'll talk about.
And then he's talking about it being a restricted time period in which he eats each day, and that for him was six hours.
And so what we're talking about here is a little different than other versions of intermittent fasting.
So let's try to separate these different versions for people.
Okay.
So originally, the term intermittent fasting was used to describe behaviors like alternate day fasting.
You know, you eat Monday, you don't eat Tuesday, eat Wednesday, that kind of thing.
Or maybe you eat significantly less on those fasting days.
There's also something called five and two, which would be you eat for five days a week, you fast for two days a week.
And so it would make sense to call that kind of thing intermittent fasting.
But what we're mostly talking about nowadays colloquially is time-restricted eating.
We're restricting the eating period to a specific number of hours during the day, and then not eating outside of that.
For the purposes of our conversation today, that sounds like it's a pretty important distinction to make.
This idea that what most people now think of as intermittent fasting is still eating something every day, but just having a shortened window of time where you're consuming food.
Yeah, exactly.
And the most popular version of time-restricted eating is like the 16-8, 16 hours of not eating, and then 8 hours of eating.
That's been the most widely discussed version of this, but it could be anything.
It could be 14-10 or 18-6.
But generally, to call it time-restricted eating, there is some kind of restrictive component here, right?
You can't eat for 23 hours and then fast for one and call that time-restricted eating, I think.
Yeah.
Gotcha.
Gotcha.
So Matt, will you tell me a little bit about the history of time-restricted eating?
Because again, it sounds like we're going to be really specifically focused on a type of daily fasting that includes a shortened eating window.
And so I know that fasting itself has like a hugely long complex history, but I'm really interested in the history around time-restricted eating.
Yeah.
And I think it's really interesting history.
I'm actually really excited to talk about it.
But you're right.
Most people, when they talk about anything related to intermittent fasting or time-restricted eating, they launch into the history of fasting and talk about, you know, like religious fasting and, you know, political protest fasting.
And they start talking about Hippocrates and Plato.
And that makes no sense in this context.
So the history of time-restricted eating really starts with the ideas of circadian rhythms.
So I think we should start there.
Okay, let's do it.
So circadian rhythms really means the patterns that occur in our bodies during the cycle of about a day.
So the term circadian rhythm first used in 1959, and it describes something that, you know, I think we've understood or suspected about the world for like all of history, which is there is something innate about this whole day and night cycle, right?
We get sleepy at night, we wake in the morning, and we see this in nature, right?
Like certain flowers close at night and open in the morning.
And, you know, there's these things that aren't necessarily just the result of external stimuli.
Like even without light, potentially, we have things holding us to this day and night cycle.
Is this idea at the core of what we're talking about?
Yeah, no, for sure.
I think that most people kind of intuitively recognize that there is a pattern throughout our days that can affect how we feel on multiple levels.
Yeah, and the study of this, the study of like timing processes and living things is a field called chronobiology, which I think is just so cool.
Oh, wow.
New term for me.
I have never heard that term before.
Yeah, chronobiology.
And the origin story of this field really starts with a guy putting a house plant in his kitchen cabinet, which is a great origin story for a field.
Back up.
Back up.
He does what, exactly?
All right.
Do you know that plant?
It's called like a sensitive plant.
Have you heard of that?
No.
So it's a plant where if you touch it, it kind of curls up in response to your touch.
Have you ever seen that?
Yes.
Yes, that I have seen.
It also does the same thing with these day or night cycles.
So at night, it kind of like curls up and closes its leaves.
And in the morning, it opens them back up.
So in 1729, a French scientist said, hmm, what if I put this plant in my kitchen cabinet?
It won't be able to see the light.
What happens?
And what do you know?
It still closed its leaves at night, even though it was in total darkness and opened them during the daytime.
So that was the first sort of like formal confirmation of this thing, I think we've suspected that there's something deeper happening here than just a response to light.
There's some kind of innate timekeeping happening here in a plant, which is so fricking cool, right?
Yeah, I mean, totally fascinating.
And my guess is that then from there, people were curious about whether or not the same type of like rhythm applied to human beings.
Exactly, exactly.
And much later in 1962, there's a great experiment, a man named Michel Siffre was a speleologist.
You happen to know what a speleologist is?
Oh my gosh, you are like testing my vocabulary today in a major way.
I know.
I have no idea.
Oh, I had no idea either.
It's a cave explorer.
Of course it is, obviously.
So Michel Siffre is a cave explorer, and he conducts an experiment on himself again in 1962, where he went deep into a cave without natural light, and he stayed there for over two months.
Ah, the experiments of the 60s.
How I love them.
He monitored his sleep and his wake cycles, his eating cycles for over two months.
And then he came up above ground, and he reported that mostly he kept to a cycle of behavior that was about 25 hours.
So about a day, circa a day, he had a circadian rhythm to his life down there with his sleep and wake cycles and his eating cycles.
And so it was like a version of putting a plant in a cabinet, except you put a French scientist in a cave.
Gotcha.
Gotcha.
Okay.
So I'm sure people listening are wondering, as am I, how did this field of chronobiology then become research into eating or food timing?
Yeah.
So all of these early studies, you know, the plant in a cabinet, Frenchmen in a cave, those are important elements of the research history here.
And those are all sort of making this early case that we have these circadian rhythms that don't necessarily tie us to the stimuli that we take in.
But we do suspect that stimuli is important.
And food is a stimulus, a lot like light is a stimulus.
And so the research in the early 2000s starts to get into this idea of like, what if we mess with these stimuli?
Like, what if we, you know, obviously, there's a long history to sleep deprivation and light deprivation research.
But with food, what happens if we make mice eat at weird times of day?
Like, how does that affect their internal timekeeping?
And so that's really where this research kicks off.
Oh, okay.
Poor mice, huh?
I always feel so bad for mice.
I know, especially because when you're trying to figure out internal timekeeping, you have to sacrifice mice and, you know, look at their livers and look at gene expression.
And it can get quite complicated, or it can be more of like an experiential, you know, like jet lag look in rodent studies as well.
But ultimately, these are important early studies in rodents, because they give us this idea that food is one of these external stimuli that could impact our internal timekeeping.
And that's significant because these circadian rhythms are super important.
You know, they keep us tied to these cycles, these like this ebb and flow of hormones rising and falling in our body.
Like an example being melatonin levels rise at night and fall in the morning.
And, you know, that helps us with the sleep and wake cycle, get sleepy at night, waking in the morning.
But there's so much more than that.
There's rhythms to how we metabolize food, utilize nutrients, how our digestive system moves, even how our blood pressure rises and falls in certain times of day, changes in our body temperature.
So we really are tied to this rhythm of day and night cycles, these circadian rhythms.
And the idea in this early rodent research is like, hey, if food is an important stimulus, how do we manipulate our eating to better sync ourselves with our internal timekeepers?
Does that make sense?
Yeah.
It's so fascinating.
And I can totally see how this is laying the groundwork to look into intermittent fasting or to try to understand intermittent fasting.
And so what I am curious about is, when does this preliminary research start to shift to looking at like an intermittent fasting model of eating?
Yeah.
So that's in the 2010s.
We start to get into actual research questions around something that we call time-restricted eating.
And the OG researcher here is Dr.
Sachin Panda from the Salk Institute for Biological Studies.
And anyone who has been interested in this research in the past has heard of Dr.
Panda before.
Great name.
Great name.
Great name.
His early research in 2012 was looking at what happens when we manipulate the feeding time of mice, and we do an actual time-restricted eight-hour window in mice when they would normally eat, which is in the nighttime since they're nocturnal.
And we compare that to mice that eat around the clock, have free access to food, 24 hours.
And this early research suggests that we actually do have some important changes in downstream health outcomes, especially metabolic health outcomes.
I said we, but I meant to say rodents have a notable change in metabolic health outcomes when they eat differently over a period of time based on the timing of their eating.
And so that early research really sparks this whole field of time-restricted eating and popularizes it because the outcomes of this research are both interesting from a science nerd standpoint, but they also kind of capture the attention of diet culture because we start to see weight changes in mice that do time-restricted eating versus mice that don't do it.
See, I was wondering when the weight loss component was going to come into the conversation.
And it sounds like these are like the preliminary studies that show maybe like weight differences in rodents that maybe were then kind of like capitalized on by diet culture and then extrapolated to humans.
Yeah, exactly.
And this is early research in mice, but it does not stop it from becoming really popular.
Whereas people start saying, I guess it doesn't matter what you eat at all.
The question is when you eat and time-restricted eating and intermittent fasting more broadly starts to become a popular weight loss technique.
Well, and did Dr.
Panda's research shift eventually from rodent models to research in humans?
Because I think that's obviously we've said this on the show before, like a super important distinction to make is we want to have human data, not just animal model data.
Yes, definitely.
And so towards the end of the 2010s, we started to get into pilot studies in humans.
So if we follow Dr.
Panda's work, so in 2015, he publishes an article that tries to first define what typical eating patterns look like for people at baseline.
So this is trying to get a lay of the land.
What is the eating window of the average person?
Okay, what did he find?
Well, he does this in an interesting way, let me say.
So he makes a phone app called My Circadian Clock.
Have you heard of that?
No, I've heard of nothing.
The theme of this episode is Jen has heard of nothing, not chronobiology or this app that you're talking about.
So My Circadian Clock is this app, and folks were encouraged, again, this is 2015, folks were encouraged to download the app, snap pictures of their food or type in every time they eat or drink anything.
And the idea here was it gave researchers, like Dr.
Panda and his team, data about when users were eating or drinking.
It's not so much what they were eating, it's when they were having these ingestive events where they were eating or drinking something.
Okay, gotcha.
They did get quite a few folks to participate.
Enough that they were able to report on 26,676 individual ingestive events in this article that came out.
Ingestive events?
It's not like the real term that they used.
That's such a like white coat nerd way of saying eating or drinking.
I know.
I had an ingestive event of oatmeal this morning for my breakfast.
And so what they found was that more than 50% of people had an eating window of over 14 and a half hours.
Okay.
All right.
So this is like general average.
Like the average of all the data that they got from this app was that people tended to eat around like a 14 and a half hour window of time.
Yeah.
I don't know statistics to know if that's the appropriate way to say that.
I'm going to say what they said, which is more than 50% of people had an eating window of over 14 and a half hours.
Okay.
So if this longer window of eating is quite common, the question becomes like, are there benefits to reducing this window in humans?
So I guess rather than going through individual studies here, I want to zoom ahead like seven years, and I want to talk about a review article from 2022, again, by Sachin Panda.
So now we're actually 10 years out from the original rodent study.
He's able to write a review now, referencing dozens and dozens of both rodent and human studies.
So a lot has happened pretty quickly as far as scientific research goes.
Okay.
And what did this review article state?
So the review makes the case that we can experience improved health, especially metabolic health.
So things like reduced risk of type 2 diabetes, high cholesterol, liver disease, by adopting an eating window of 10 hours or maybe even 12 hours.
Okay.
So it sounds like looking at the research over the past decade, the conclusion that Dr.
Panda and his group of researchers come to is that there seems to be metabolic benefits to having a slightly abbreviated eating window, which is actually, I mean, this is interesting to me because I, I would imagine this is not the type of window that most people think about when they think about intermittent fasting.
Like I would imagine most people view intermittent fasting as having a much shorter window of time where you're able to eat like four hours or six hours.
This sounds like a much longer window of time where there are still metabolic benefits.
Yeah, that's what stands out to me.
And why I wanted to really talk about this is we're not really talking about a six-hour window or even an eight-hour window necessarily.
We're talking about up to 12 hours and we're seeing metabolic improvements.
And there are associations with other health outcomes, too, that we're not going to get into today.
But specifically with these metabolic health outcomes, you know, we're seeing it in these small early pilot studies in humans with up to a 12-hour window, which I think really flies in the face of how we tend to talk about intermittent fasting or time-restricted eating like colloquially.
So I think that was important to call out.
The other thing is this review also recommends that, you know, based on the research we have thus far, the emphasis is not put on waiting to eat until later in the day.
It's actually put on eating earlier in the day.
Oh, interesting.
Tell me more.
So the reason for this goes back to an understanding of circadian rhythms.
You know, we've known for decades that at night time, melatonin levels rise, that inhibits insulin release from our pancreas.
And then in the morning, we see these insulin levels rise.
And we know that for most people, we get the best blood sugar control in the morning hours.
And that kind of tails off a bit throughout the day.
And so with that in mind, there has been some research that looks at early eating compared to late eating.
And we find that there are some metabolic benefits to eating earlier.
And so the review says, hey, if you're gonna try to keep your eating to under 12 hours, you might experience benefits.
And if we can make those hours include morning, that might offer benefits as well.
And so I think that's interesting.
It's not my recommendation necessarily.
I'm not saying I agree or disagree, but I think it's very different than the cultural conversation we're having about intermittent fasting.
Yeah, I mean, I think the thing that might surprise most people listening is that actually the recommendation is to eat breakfast, which is the exact opposite of how I see intermittent fasting play out for most people.
I think the general idea of intermittent fasting is don't eat or push off eating as long as possible over the course of the day, and then maybe have that shortened window in like the middle of the day.
But just to make sure we're being like ultra clear, I think about Matt that one of the most like common diet culture tropes can be, oh, don't eat anything after 5 p.m.
or stop eating after 6 p.m.
It sounds like from what you're telling us that there's also not like a recommendation to not have dinner, right?
Right.
Absolutely not.
And that would actually make this much harder to do is if you're undernourished during the day and then you're hungry all night, but you're in your fasted window, there is not a recommendation to intentionally restrict your calorie intake.
It's to restructure your day if you're somebody who doesn't eat breakfast.
I see that.
I think that's a really important distinction too, because again, many people, I would imagine, think about reducing their caloric intake.
It sounds like again, that's not even what the research necessarily suggests.
I think that in a 12-hour window, people could have three meals, multiple snacks, and still get the benefits that Dr.
Panda and his group have observed.
Yes.
And I'm just going to go blue in the face saying, in these early studies, and we have a lot more research that needs to get done.
But yeah, exactly, exactly.
That's what struck me, too, is in a way, time-restricted eating feels a lot less restrictive than I kind of thought it was going to.
Yeah.
No, for me, too, given what you're describing, I guess I'm also curious about why keeping to a window of less than 12 hours would potentially lead to these metabolic benefits.
Like, is there any understanding of why this, like, slightly abbreviated window of consuming food impacts or has, like, health benefits?
Yeah, that's a really good question.
And there's a lot of people that seem to think they know exactly what the answer is.
My take, and I honestly think Dr.
Panda's take as well, is we're lacking these mechanistic studies that would really help us get a super deep understanding of what's happening here.
There's a lot of great ideas, but the theories are about how eating periods and non-eating periods are kind of similar to sleeping periods and non-sleeping periods.
Like, you know how when we sleep, there's these unique processes that help restore or repair our body, right?
The same theories kind of come up in the time-restricted eating literature about how we have certain processes that happen when we're not eating.
And these include like increasing DNA repair, increased antioxidant levels in the body.
There's a process called autophagy, which is sort of like this.
That's such a big buzzword right now.
We should do an episode on autophagy, because I feel like I hear that everywhere right now.
Shot not.
That's your episode.
No, thanks.
So autophagy, well, it's sort of like a cellular cleaning process, right?
And so similar to sleep, we think of almost like a cleaning or restorative process that happens when we're not eating.
And it can also have to do with energy utilization.
Like, what is our energy source at a given time, glucose versus ketone utilization thing.
But we won't get into that today.
But ultimately, I think we have more to understand about it, but it doesn't necessarily change the fact that in this early research, we are seeing improvements that suggest that there is a benefit for some people when they're cognizant of timing as part of their eating routine.
So interesting.
But it also sounds like we're not really even 100% sure why.
There needs to be a lot more research into understanding the why behind seeing some of these physiological, positive physiological changes.
Yeah, exactly.
And there's been some folks who say, well, maybe it's because people are losing weight.
Like, is this just the result of weight loss?
And interestingly, it appears to not be the case.
A lot of the metabolic benefit is exclusive of weight changes.
Ooh, that feels like it's important to call out.
Put slightly differently, like the explanation for these metabolic health improvements ascribed to time-restricted eating are not just due to eating less calories and forcing weight loss.
There really appears to be something about this circadian rhythm thing that can potentially be helpful even when weight stays constant.
So that is very important, very interesting.
And that's where we are today.
There definitely have been studies since this review in 2022, but nothing that dramatically changes the story, to be honest.
It kind of reminds me of how we know that getting adequate sleep is important.
We know that there's a window of sleep that helps our body just feel better and physiologically work better.
And it sounds like this is research into understanding how that same process applies to food.
Yeah.
No, that's a super important point.
I think the circadian rhythm thing is way more compelling than the time restriction thing.
We don't have any problem.
It's not problematic to say, I'd like to get more sleep, right?
And I think that there's an element to this research where I think that there's some almost universal public health ideas that could become pretty important in the future.
And if we can put aside the diet culture BS and even the idea of restriction at all, we could just embrace some ideas that could be quite helpful for people going forward.
Can you talk more about that?
Because I'm curious to know your thoughts about how it could be presented in a non-restrictive, non-diet culture way.
Yeah.
Well, you know, any large scale recommendation is not going to be applicable for everybody, right?
So there's certain people who just straight up should not be thinking about this stuff, right?
Right?
Like if you're managing a super complex health condition and eating at night is like the only time to eat for various reasons, you take a certain medication that requires eating at a certain time.
Of course, this would discount you.
The other thing I'll say, too, before I answer your question, is this whole conversation like leaves out night shift workers completely.
There are some people who are just being like burned by this research because their circumstances of their life have them working at night.
And like, thank you nurses for being awake at three in the morning.
And like, that's the time you need to eat.
Or like everybody else working at 24 hour gas stations in the middle of the night.
So there's a lot of caveats here.
But what I guess what I mean is for somebody who is in a somewhat normative cycle of day and night living, a public health recommendation could be focus on eating breakfast and give yourself time to digest before bed.
And I think largely that would not be a very problematic or restrictive recommendation if the emphasis is put on eating enough during your daytime hours so that you're not in need of nourishment at 11 p.m.
when you want to go to bed.
Yeah, but come on, Matt.
That's not going to get likes or follows on social media.
I know.
But you know what?
Nobody looks at my plate anyway, so let's just put it on there.
No one will read it, but at least it's there.
Well, I mean, again, I think it's this.
There's this the big line or the big distinction we have to make in this conversation is the difference between, not even difference, like the huge gap and divide between what the research around time-restricted eating says, and then how intermittent fasting is kind of portrayed in our culture and on social media.
Right?
There is no recommendation to skip breakfast.
There is no recommendation to like restrict your calories.
There is no, it doesn't seem to me, just by our conversation so far, benefit to only eating within a four-hour window.
This is very different than what the research is suggesting to us.
Yeah.
And I think we're kind of transitioning here to like, what are the problems with time-restricted eating in the way that we often talk about it culturally?
Right?
And so, I mean, people seem to think that just because they say they're doing time-restricted eating or intermittent fasting, that they're like protected from being starving when they undernourish themselves.
And that is not the case.
Just because you're calling it intermittent fasting does not mean that this isn't a restrictive diet if you're not eating enough.
Oh, for sure.
I mean, I guess I would also say that, you know, intermittent fasting has been turned into a diet in many ways.
And because of that, this could be problematic for a whole subset of individuals because it could lead to disordered eating, the development of eating disorders.
Like, I'm not sure, Matt, if you came across any research as you were digging into this topic around association with eating disorder pathology.
But I could also imagine that this style of eating, taken too far or misinterpreted, could potentially lead to people having a really, really negative relationship with food.
Oh, absolutely.
Yeah.
In fact, I'm glad you brought it up.
So there was a study, Canadian study in young adults and adolescents.
And so, you know, this kind of looks at eating disorder pathology and intermittent fasting.
So I'm going to give you a quote to read here.
Okay.
It says, quote, overall 48% of women, 39% of men, and 52% of transgender or gender nonconforming participants reported engaging in intermittent fasting in the past 12 months.
Intermittent fasting in the past 12 months and 30 days was significantly associated with eating disorder psychopathology among women, men, and transgender gender nonconforming participants.
Varying patterns of association between intermittent fasting and eating disorder behaviors were found across genders with the most consistent relationships between intermittent fasting and ED behaviors in women.
Yeah.
Okay.
I mean, so this is exactly what I would imagine or suspect, is that intermittent fasting can become very extreme and therefore lead to disordered eating or eating disorder symptomology in individuals.
Oh yeah, definitely.
And you know, you and I, we're boots on the ground dietitians here talking about people's eating patterns all day long with folks.
And I mean, that rings true for us.
I know, you know, intermittent fasting is often one of the diet approaches cited in diet histories amongst people who are trying to build a healthy relationship with food.
And they reflect back on intermittent fasting, the way they reflect back on the keto diet or paleo or the whole 30 or on and on, Weight Watchers, Noom, on and on.
So, you know, this gets lumped into a very similar way of thinking about dieting.
And that's largely due to our cultural conversation.
So, I'm kind of hoping that what we're doing today is starting this shift away from restriction and towards some of the more interesting, you know, circadian rhythm research.
Yeah, I mean, again, I just think it's the divide between how intermittent fasting is portrayed on social media and in diet culture versus the research.
The research is so interesting.
The research question itself is fascinating.
And it seems like, yes, the research is preliminary.
And again, I think that's super important to come back to.
But it's just leading to more research questions about how eating and the timing of eating throughout the day can impact our circadian rhythm, much like the way that we've been studying sleep for many decades.
Yeah.
And I think a lot like sleep.
Some people get very black and white about it.
Like, oh, I need exactly eight hours of sleep.
And if I don't get it, I get very anxious about how that's affecting my health.
I think it's similar here, where people get very rigid about elements of the time-restricted eating research.
Like, what constitutes breaking a fast?
Or, you know, oh no, my circadian rhythm is off because I ate breakfast an hour later.
And, you know, I'm left with this feeling of like, we have no idea how clinically relevant any of that stuff is.
So I would encourage people not to get too wrapped up in these discussions on, you know, other popular podcasts about exactly what your windows should be.
I think we need to take the restriction out of time-restricted eating.
I like that.
Let's do it.
Time eating.
That's all we've got left.
How about just like eating?
Eat some food.
Yeah, and the other kind of burning thing I want to say is like, this is just one aspect of eating.
Like, there's so much to think about, right?
Like, this is not a panacea.
If your goal is to have improved metabolic health, you could approach that a million different ways that have nothing to do with anything we discussed today, right?
There's other ways to approach these goals.
This is just one piece of it.
It is interesting, but one piece of it nonetheless.
Yeah, I mean, I think that's such an important point, Matt, that there are many ways to approach the goal of maybe like improving cholesterol, or, you know, helping to optimize blood sugar control.
I guess one of the things that comes up for me is, I would imagine that people listening could now maybe be worried about what happens if they're hungry late at night.
I guess I'd be interested to hear your thoughts around that.
Yeah, I'm glad you brought that up.
My thought is eat when you're hungry.
I mean, at the end of the day, intuitive eating, I think, can square with this in the right framing.
And so if we're honoring our hunger, and, you know, our best intentions are to care for ourself in a way where most of the time we're not hungry in the middle of the night, that's a good goal for yourself, right?
But if you're hungry, honor your hunger.
And, you know, listen, my wife is pregnant.
I'm going to have a screaming baby in my house soon.
You better believe I'm eating some 2AM snacks soon.
Like this does not influence my own personal behaviors.
Yeah.
Yeah.
Well, and I mean, I guess, you know, I guess the other question too is like, is there a way to square these ideas, you know, the time-restricting eating research with what you and I would consider weight-neutral health-promoting behaviors?
Yeah.
Yeah.
I think there is, right?
So, weight-neutral health-promoting behaviors is a phrase we really love, meaning like, how can we focus on improving our health behaviorally without a direct focus on weight control?
Like, if we put weight aside, how can we think about behaviors we might want to engage in?
And so, I think there is a way to match these things up.
Like I said, I think we need to get rid of the name time-restricted eating.
I don't think the word restriction has any place in weight-neutral health-promoting behaviors after the trauma we've all been through.
I think it's not about time restriction.
It's about syncing our eating with our internal timekeeping to the best of our ability when we can.
So, I would call this something like time-synced eating or circadian eating.
You know, it isn't about rigid windows.
It's about trying, when possible, to eat enough during the day to allow for yourself to have a couple hours to digest before bed.
I really think it's as simple as that.
I love it.
I love that, right?
Because again, I was going to say the same thing.
I would distill this down to like, having breakfast is great and important and makes you feel better.
And then just maybe like notice how you feel when you give yourself some extra time to digest before bed.
Yeah.
And listen, some folks are not going to be breakfast eaters, and they're going to be listening to this, and they're going to go, these two have a bias.
These two have a bias for breakfast.
Yeah.
We do, right?
Talk to me about why we've earned a bias for breakfast eating.
We have such a breakfast bias.
I have a breakfast bias t-shirt, but that's another conversation.
I think it's probably because in our clinical practice and working with folks that, at least I can speak for myself, I have noticed that many slash most people tend to feel much better if they're nourishing themselves in the morning and not pushing off eating too long.
I think many people tend to have more energy, more focus, more concentration.
They might notice improvements in mood if they're not waiting an extra five or six hours after they get up to nourish themselves.
I totally agree.
I mean, we see this time and time again.
Anyone listening who's sort of a boots on the ground, registered dietitian working with folks notices this pattern, which is a lot of people wait a long time to eat breakfast or they have a light breakfast, they have a light lunch, then they get home, they're starving, they're eating while they're cooking dinner.
And the most of their eating has to happen later in the day.
That changes what we're in the mood to eat.
It changes the experience of eating.
It changes the mindfulness component of eating.
And it just changes our personality in ways compared to somebody who is better nourished earlier in the day.
And, you know, also being eating disorder clinicians, one of the biggest red flags that somebody is struggling in their recovery is breakfast falls off.
I mean, wouldn't you agree?
Yeah, I mean, I think it's really interesting, right?
You and I try not to make too many individual recommendations on the show because that's just impossible to do when we're talking to a broader audience.
But I think this is more of our interpretation of the research combined with what you and I have noticed after kind of extensive clinical practice.
Right, exactly.
I'm kind of reminded of our episode about saturated fat, where there was like, yeah, well, you know, we looked at the research, and it does look like there's some recommendations to be had here.
I'd love to say, just like eat literally anything that feels good for you.
And that's going to be associated with decreased cardiovascular disease risk.
But, you know, we have to be research based.
And so this is one of those episodes where we're looking at the research and going, yeah, there's some interesting stuff here.
More to be learned.
A lot like saturated fat, a lot more to be learned.
But that's where we are at this time.
Yeah.
Yeah.
I mean, I think lots of areas of future research.
And again, I would probably also point out that this seems like a very new area of research.
We're talking really only over the last several decades.
And so I'd also be curious to see what we learn over time, like over the next 20, 30 years, around time-restricted eating and just how it might impact metabolic markers of health.
Yeah, totally.
It's exciting stuff.
All right.
Well, I think we did what we came here to do, right?
We talked about time-restricted eating and intermittent fasting and gave our thoughts.
And hopefully this was interesting and helpful.
I have no idea how to end this episode.
Do you have any ideas?
No, that's okay.
Let's just pack up our breakfast bias and we will see ourselves out.
All right.
I'll see you next time, Jen.
Alright. See you, Matt.
Nutrition For Mortals is a production of Oceanside Nutrition, a real life nutrition counseling practice in beautiful Newburyport, Massachusetts, where we provide individual nutrition counseling, both in person and online via telehealth.
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