Aidan:
Hello and welcome to the Ideal Nutrition Podcast. My name is Aiden Muir and I’m here with my co-host Leah Higl. And this is Episode 105 where we are talking about whether eating breakfast helps weight loss. This is a topic that goes back and forth in the media all the time. One thing that I find super interesting is that I, not the thing I’m most proud of, but I spent a lot of time reading Alan Aragon’s research review dating back to like, I don’t know when, it was like 2007 or something. It was, I don’t know, there’s been a lot of hours poured into reading old copies of this research review that’s just summarising research as it comes out. And very wild to think that every month pretty much, he is summarising a new study on whether breakfast helps weight loss or doesn’t. And they have different findings very often, which we’re kind of going to talk about and summarise a little bit.
But it’s interesting being like, one month we’ll be like, okay, this one it helps weight loss, the next it doesn’t. And I’m like, why does this exist and everything like that. What does it look like on balance? Obviously we have answer to that as well, which we’ll talk about, but you can see why in the media and everything like that, people will latch onto each one as it comes out because it’s new, interesting etc. And you can also see why that if you went into this topic with a bias in either direction, it also wouldn’t be too hard to find something that confirms that bias as well.
Leah:
Let’s start by talking a little bit about at least the underlying mechanism of weight loss. So for weight loss to occur, you have to consume less calories than you’re expending. There is no way in getting around this calories in versus calories out concept. However, in theory, if breakfast versus not having breakfast was to either directly or indirectly affect either side of that equation, it would then either help or hinder weight loss. So if having breakfast increased energy expenditure or decreased energy expenditure or the other side of the equation, it increased slash decreased calorie intake, then it could then affect weight loss to a certain degree. So we’re going to talk through a little bit more about that in depth.
Aidan:
Cool. So before talking about either total daily energy expenditure or talking about intake as well, I’m going to talk about one component of total daily energy expenditure and assess the claim that breakfast helps speed up your metabolism. If that is taken overly literally, and I don’t think this is what people mean, but if it’s taken overly literally to mean that increases your basal metabolic or your resting metabolic rate, there’s no evidence to indicate that the broader claim of increasing energy expenditure, if we just called that metabolism, that’s a bit more open to interpretation, but in terms of basal metabolic rate, there’s no evidence to indicate that. And one of the tough things about prepping for this podcast is it was involving a lot of reading stuff that I already knew just to make sure I got clear numbers and everything like that, that I can present in a well formatted way that couldn’t be argued against or anything like that.
But with this basal metabolic rate thing, it’s actually hard to find evidence on this specifically. And the reason why it’s hard to find that is because basal metabolic rate is so much more skewed by other variables, such as changes in calorie intake, that it would affect the impact on your basal metabolic rate so much more than skipping or eating breakfast. Using an example, if skipping breakfast reduced your calorie intake, that would reduce your basal metabolic rate if you did that consistently over time, due to being in a calorie deficit and the impacts that that would have on your basal metabolic rate. If skipping breakfast increased your body weight over time, that would increase your basal metabolic rate over time. So it’s like the other variables actually have a much larger impact on that. But in isolation with all other factors equal, eating or not eating breakfast doesn’t really impact your basal metabolic rate.
Leah:
Talking about the next topic, does does breakfast increase total daily energy expenditure? So talking beyond metabolism or metabolic rate, does it increase total daily energy expenditure potentially through things like increased incidental movement and/or physical activity? So surely if somebody ate breakfast, they would move slightly differently throughout the day or that kind of first half the day versus if they didn’t eat breakfast. So does someone who eats breakfast end up burning more calories just because they get up, they have breakfast, they have more energy, and therefore move more throughout the first half of that day? We have some observational evidence for this, but most of that indicates a reduction in physical activity among those that skip breakfast, which kind of plays into the fact that oh, if you have breakfast, then potentially you’re more physically active, therefore increasing your total daily energy expenditure. So that sounds pretty promising for having breakfast, but this isn’t exactly proof that skipping breakfast causes that outcome. It is just observational.
And if you are someone who keeps exercise and daily steps pretty consistent, particularly if you’re someone who is, say, counting steps and keeping your training very consistent, this would obviously play very little, if any role if you’re just on purpose keeping all that consistent regardless of if there is breakfast or no breakfast.
We have linked five randomised control trials in the show notes on this specific topic too, and three of them found no significant difference between the total daily energy expenditure or physical activity of people who ate breakfast versus not. But two found that eating breakfast did actually increase physical activity. So generally it is a very mixed bag.
Aidan:
And with the observational evidence that typically does lean in favour of eating breakfast equaling slightly higher physical activity, one thing I touch on with that is that almost all of that research is done on children and adolescents, like school aged people, and is that as applicable to somebody who’s like, oh, I skipped breakfast to then go to the gym in the morning or something like that? It is very, very different scenarios, which I would just factor in with the observational evidence. But looking at research directly, looking at total daily energy expenditure, which would combine all of the variables of basal metabolic rate, thermic effective food, incidental movement, and formal physical activity, the most tightly controlled research we have on this topic has found no difference in 24 hour energy expenditure. So that’s a pretty big nail in the coffin of breakfast speeding up your metabolism. Because if it was actively breakfast in isolation speeding up your metabolism or increasing total daily energy expenditure and there was a clear link, we would be seeing it in this type of research.
But there obviously can be individual exceptions to this. Because if you are somebody who noticed a huge difference in your desire to do physical activity if you ate breakfast versus if you didn’t eat breakfast, that would have a pretty decent impact on your total daily energy expenditure. One of the things with this tightly controlled research in comparison to observational research, is that they are controlling for the variables of exercise and everything like that as well. It’s not like they’re in a scenario where they give these people breakfast and they move more later in the day. Oftentimes they’re in a room the entire 24 hours, but it’s just, I don’t want to say proof of concept, but it’s just being like this is how they measure to make sure that breakfast in isolation isn’t actually doing anything magical to 24 hour energy expenditure.
You’ll notice that I’ve used the word 24 hour energy expenditure instead of just total daily energy expenditure. Really the same thing. But the reason why I’m specifying 24 hours is because if we were measuring energy expenditure over a shorter time frame, it could be skewed by other variables. For example, if we got a group of people at 8:00 AM and gave one half of them breakfast and the other half we gave nothing and we measured for a four-hour period, we would likely see higher energy expenditure in the breakfast group because they’ve eaten food. And the thermic effect of food would increase calories burned. But if you balanced total intake out over 24 hours, the thermic effect of food would likely come out relatively similarly, or at least the differences would be small enough that we wouldn’t see a difference in 24 hour energy expenditure, which is what we see.
Leah:
Getting onto the next topic, does eating breakfast reduce energy intake elsewhere? And now that’s something that I see kind of crop up all the time, in that if you eat breakfast, you’re less likely to eat more food throughout the rest of the day. And theoretically if you have breakfast, potentially you are less hungry and that could lead to fewer calories consumed over the course of the total day. So a classic example of skipping breakfast would be if someone doesn’t eat breakfast and then is starving in the middle of the day or in that kind of classic afternoon period, and therefore eating more food in total, usually going for more discretionary or junk foods, a little bit more highly palatable, over the afternoon or during that nighttime period. From the opposite perspective, however, adding breakfast could also simply just add additional calories to the day. So in my experience, it can be really different strokes for different folks, in that for some people skipping breakfast doesn’t really impact their appetite management throughout the day and therefore doesn’t lead to this overconsumption of food later in the day. But for some people it does.
So some of my clients are not breakfast eaters and actually to almost fast in the morning when doing a weight loss phase, and that works super great for them, whilst others may skip breakfast and end up being like so ravenous throughout the rest of the day that their nutrition plan goes out the window and they end up just over consuming food just because their appetite management was really poor from skipping breakfast. And obviously if that’s happening regularly, that is going to hinder weight loss in general. So whether or not breakfast reduces or increases energy intake elsewhere, I think it can realistically go both ways.
Aidan:
And I think that’s a good summary. I agree from that perspective. I think different strokes for different folks, paying attention to what works well for you and everything like that. And honestly we could mostly leave it there and anything beyond this point is mostly academic.
Leah:
It’s worth adding context.
Aidan:
Yeah I think so. Yeah. So I’m going to continue just talking about a bit more research and stuff like that, to see averages I guess. One thing that was interesting about the whole concept of adding breakfast could just add calories to your day, is going through all of those studies that were in Alan Aragon research review. I didn’t put this one in the show notes because I haven’t been able to find it since, but there was an interesting study that month after month after month of it going backwards and forwards, there was one study that got a bunch of habitual non-breakfast eaters and got them to add something along the lines of a 400 calorie breakfast and it literally increased their intake by 400 calories pretty much. And I was like, that’s a really interesting starting design because a lot of the stuff we’re looking at isn’t just done directly on, these are people who don’t eat breakfast. Let’s see what happens when they add breakfast.
A lot of the research that people are pointing to is the observational type stuff, being like let’s compare breakfast eaters to non-breakfast eaters and see what happens. Yeah, talk more about that. But the next thing I did want to talk about is let’s just simply look at what a 2019 systematic review of all of the randomised control trials on breakfast intake and calorie intake has found. And that had a very interesting finding. They found that people who consumed breakfast in these studies ate an average of 260 calories more than those who skipped breakfast. And that indicates a combination of both of those points that you mentioned earlier, about on the one hand, eating breakfast could add calories to your day, which it did in this example, but on the other hand it could make it easier to consume fewer calories throughout the day, “make better choices” rather than being starving in the middle of the day, et cetera. Because the breakfasts they added were larger than 260 calories, they were probably 400 calories plus, which therefore means they did reduce their intake later, but they added slightly more calories overall.
Once again though, just doubling down the point of these numbers, our averages individual experiences vary. Sometimes people add breakfast and it just is a game changer. It dramatically reduces their calorie intake elsewhere. Other people, skipping breakfast is an easier way to reduce calorie intake. So averages, I think that’s interesting. It’s worth knowing, particularly when you’re talking to other people, because if you find something that’s worked well for you and you recommend it and they got a completely different experience, it’s kind of useful to know about these averages existing.
Leah:
100%. And I think that’s why it’s definitely worth us touching on research on intermittent fasting just because, I mean I explain fasting sometimes to my clients as a fancy way of saying skipping breakfast, because I think to a certain degree that’s kind of what it is. So technically research on skipping breakfast does not directly overlap with research on fasting, but skipping breakfast does not also have a defined timeframe. So that’s the difference, is that fasting is usually a defined timeframe where you’ll fast kind of like a 16/8 kind of fasting window where it does have that defined point where skipping breakfast is just, you still eat as normal but you skip breakfast.
Aidan:
So you could skip breakfast and starting at 12:00 but there’s no end point, whereas 16/8 fasting if you start at 12:00 you have to stop at 8:00.
Leah:
Yes, 100%. And obviously that’s a pretty big difference between the two, but I still think there’s enough overlap to kind of draw parallels.
Aidan:
Yeah, and I think the reason why it’s important to look at research on intermittent fasting is because there’s a large gap in the research if we don’t. If we just look at skipping breakfast, that randomised control trial, I believe it had about 13 studies in it, whereas intermittent fasting studies, there’s a lot more than 13 studies.
Leah:
Yes. So looking at a 2020 systematic review on intermittent fasting, it found that all 27 randomised control trials resulted in weight loss on average. Once again, this was simply due to reduction in calorie intake. So nothing else too kind of fancy going on there other than it is affecting that part of the calories in versus calories out equation. In isolation, this does look like a huge win for skipping breakfast, but it is also worth factoring in other key points. So just going through those individually: is your hunger management throughout the day, better or worse when you fast/skip breakfast? How does skipping breakfast change your behaviours in regards to both food and exercise throughout the day? What if you have training in the morning? Do you want to do that fasted? So is it worth skipping breakfast? Is it worth fasting for that outcome if you train in the morning? What if you just generally enjoy breakfast and going out to eat in the morning with friends? Is it worth having a fasting/no breakfast food rule in that case?
So even though it looks like a win for skipping breakfast, I still kind of go back to different strokes for different folks. Some people will find it a huge win. Other people, it just won’t be a huge win at all or it would just add in an extra food rule that makes things harder for them.
Aidan:
Yeah, particularly because all 27 studies resulted in weight loss. Some of them were very, very, very modest weight loss, but all 27 did result in weight loss. But that’s when all the other factors come in. And another thing to factor in with these studies is, one, duration, then it’s not like they’re fasting for a lifetime, they’re fasting for a defined period for a randomised control trial. And two, is also incentives. If you know you’re in a study for three months, for example, and you’ve just got to fast until say 12:00 PM as an example, you’re like, I can do that for three months for a study that I’m being held accountable for and everything like that. If your friends go out to breakfast on a Saturday morning or Sunday morning for example, maybe you say no during that duration, but when you’re looking like, do I want to say no for the rest of my life? That’s when a lot of other variables come into play. And then once again, different strokes for different folks kind of thing.
Leah:
It’s like, do you really enjoy doing that?
Aidan:
Yeah. A lot of angles to look at that from. So we’ve kind of spoken about calorie intake, but we haven’t directly looked at weight. So that same 2019 systematic review that found the increased calorie intake, about 260 calories, from people eating breakfast versus skipping, found that there was minimal difference between the two approaches, but there was a 0.44 kilo difference trending towards the breakfast eaters weighing slightly more. So on the one hand you could look at the minimal difference aspect. On the other hand, you could look at that as a bit of a nail in the coffin for the suggestion that eating breakfast helps weight loss. Like if you have a friend who is looking to lose weight and they aren’t eating breakfast, recommending breakfast may or may not, it’s probably like it’s not a surefire thing to help them kind of thing is what I’m getting at.
That’s the randomised control trial research, but the observational research has a bit of a different story, but we need to look at that through a bit of a nuanced lens. So the observational research tends to find that people who consume breakfast have lighter body weights than those who do not. Once again, as I mentioned, a lot of this is on school-aged children, whether primary school or high school, and there’s a lot of variables that go on when people are eating breakfast versus not eating breakfast. This doesn’t mean breakfast is the cause of that. We also have a lot of research showing that people who eat breakfast typically have diets that are higher in fibre and micronutrients, probably better quality diets overall. So the observational research does find that, but it’s pretty open to interpretation too.
Leah:
We’re going to wrap up this topic with looking at just the other pros and cons of having breakfast in general. So looking beyond just weight, there are a bunch of other things that matter and that we should consider and should be part of this discussion in general. So breakfast itself can be an opportunity to get in more of certain micronutrients or types of fibre that might not often be consumed at other points of the day. So it is often a good opportunity for most people to get in some whole grains. Usually fruit is something that is consumed at breakfast time as well as protein and calcium. So usually dairy or milk alternatives are consumed around breakfast time, at least in Australia for most people. So these are things that if we don’t have breakfast, we might be missing it, like an opportunity to get these in.
We also have research indicating that protein distribution is a pretty good thing, particularly if muscle recovery and things matters to you. So adding protein at breakfast could help with that and it could also help with satiety. So we know that protein per calorie is very satiating, so if you are having protein at the start of the day, potentially that is a good beneficial thing for satiety. Plus, I think the biggest thing to mention here is the quality of the breakfast. So the quality of the breakfast does matter. So if we’re looking at a high protein, high fibre, micronutrient rich breakfast, that is going to be very different in its pros and cons to one that is the opposite of that. So looking at say, a typical protein oats breakfast with berries and chia seeds is very different to a bowl of fruit loops. That’s going to have a drastically different impact on things like satiety energy, et cetera, throughout that period. So the quality, definitely something that matters.
Aidan:
Yeah, and that’s also another interesting point when we look at the research. Because I think it’s very useful to look at the research and everything like that, but when we have say 13 randomised control trials that we’re looking at, each of those 13 will have their own unique different methodologies and stuff like that. And it’s like how much is that say, 260 calorie number I kind of referred to, impacted by the types of breakfast that they were specifically chosen. If they had replaced all of those breakfasts that were chosen with higher protein, higher fibre, micronutrient, enriched breakfast, and then compared that, do we get a different result?
Obviously there is a different result, but that comes back to some pretty key points. Whether you eat breakfast or not in isolation, doesn’t really matter. Calories in and calories out is what controls weight loss. For some people eating breakfast might make that easier, for others it might do the opposite. And what you have in those breakfasts if you do have them, also matters and what you have through the rest of the day also matters as well. And then there’s also the personal preference component and understanding that why this kind of thing matters is because it isn’t necessary to have breakfast or to skip it. You can achieve your goals easier by understanding that because you can choose the approach that you prefer and it makes it easier for you to achieve what you would like to achieve.
Leah:
This has been Episode 105 of the Ideal Nutrition Podcast. If you haven’t yet left a rating or review, that would be super greatly appreciated. But otherwise, thanks for tuning in.