Aidan:
Hello and welcome to episode 158 of the Ideal Nutrition Podcast. My name is Aidan Muir and I am here with my co-host, Leah Higl and today we’re going to be talking about reasons you aren’t losing weight on a low-calorie diet and what to do about it. So I wanna start off by giving a super brief background on why calories in, calories out works. This could be a podcast by itself. So I wanna go kind of brief on here. And I also wanna talk about why it’s a bit of a moving target as well.
So simplified explanation is that the body is made up of calories to a certain degree. Our muscle and our fat contain calories. One kilo of body fat contains around 7,700 calories as a stat that is chucked around heaps. Every day we eat a certain amount of calories and every day we burn a certain amount of calories. If we are consuming more calories than we are burning, it has to be stored somewhere simply because calories are simply a unit of energy. They can’t just disappear. So it’s stored in our body in the form of muscle, fat or glycogen. Vice versa, if you do the opposite, our body pulls from its internal stores of muscle, fat or glycogen.
So calorie deficit leads to fat loss over time. Like that’s a, that’s a pretty simple thing from that perspective. But one of the big things that must stress with this is that it is a moving target. We don’t know how many calories we burn in everyday life. We could even go into detail about how we don’t really know how many calories we’ve consumed once you factor in things like absorption, nutrient, like label reading and all of these kinds of things, how there could be inaccuracies of all of that.
But that’s the general background. I think the general background is really important because without going through that, it’s hard for the rest of this to make sense. I think if you wanted to know more about that, you’d probably need to go to a different source to learn more about calories and why it works. But let’s then go with the assumption that calories in calories out works. We will then start talking about what are some common issues that we’d see when people are on low calories and not losing weight. Then we’ll talk through common issues about why they might not necessarily be in that situation. But then we will talk through scenarios where they might actually be in that situation, where they’re on lower calories than expected and not losing weight. Then we’ll talk about what to do if you’re in one of those situations.
Leah:
Starting with something that is not a super popular discussion amongst this topic, but something that we definitely want to cover is underreporting. Realistically, if we look at all the research on this topic, we know that people are pretty bad at reporting exactly what they do. It’s really common for people to underreport the amount of food and calories that they’re eating to a pretty significant degree. So I think a lot of the times when someone is stating that they’re on a very low calorie diet. So let’s take an example of someone on like a 1200-calorie per day diet and they say, Hey, I’m not losing weight. I’m eating 1200 calories.
I think as a nutrition professional, a lot of the time our head kind of straight goes to, okay, maybe this person is underreporting because it is something that happens all the time. It might feel like you’re eating 1200 calories or it’s something that you’re aiming to do, but is that realistically what is happening in reality? And a lot of the time it’s not. A lot of the time people are eating significantly more than they think they are, even though they might be tracking or utilising a meal plan that is quote on quote 1200 calories or very low calorie.
To give a more specific example, the most well-known study on this topic got together people who had all reported that they were diet-resistant. So meaning that they were dieting chronically and that they weren’t losing weight. All the participants had reported not losing weight on less than that 1200 calorie amount. When their metabolic rate was measured, it was within 5% of predicted values on average, meaning that there was no kind of huge discrepancy overall on average between what these people thought was their baseline calories for maintenance versus kind of what it was in reality.
So that wasn’t the issue in this particular case. When their intake was measured though, versus what they had said they’d eaten, it was found that on average they had under reported their intake by 47%. And that’s just on average. There was one participant that actually under reported by 80%. So they thought they were eating, let’s say 1200 calories, but it was much closer to like 2000 calories.
Aidan:
I’ve got numbers on that. Like I think it was, I think what they ate came out as about 3000 calories, but what they reported came out as about 800 calories.
Leah:
Oh really?
Aidan:
Yeah.
Leah:
Which is just a huge discrepancy. And none of the participants actually got within 20 % of what they thought they were consuming. So most people had underreported like very significantly. I think the 80 % one is particularly crazy. It’s, I think it’s super relevant because it is something that I see in practice quite a lot. Is this kind of very significant underreporting? Which I think is a slippery slope because then people start to really question themselves on like, is there something wrong with me? Like metabolically, is there something else happening when sometimes it is just a matter of you think you’re doing something, but you’re doing something else entirely.
Aidan:
Yeah. One of the reasons why I think that study stands out so much is both of those numbers, that 80% number and that 20% number, the 80% number I don’t want to get too deep into, but it’s like when you see very outlier cases that you’re like, Hey, this doesn’t line up with how the body works, et cetera, et cetera. It’s worth knowing that like, well, in that one study, we have not a massive, massive sample size. If somebody under reported by 80%, in the real world, we will see stuff like that, like pretty commonly, like it will happen. Like as a percentage, it’s a relatively small amount of people who would under report by that much, but it also does exist. And if you speak to a lot of people about this, you will come across stuff like that.
But the 20% one, I love that one just because I can look at that through a very positive lens about the fact that it’s like, I think a lot of people are very honest people and they’re doing the best to say what they believe is happening and everything like that. And I’m like, if nobody in that study got within 20%, then it would make me pretty silly to therefore believe that anytime somebody tells me exactly how many calories they believe they’re on, it’d make me pretty silly to believe that’s like, no, that is exactly what they’re on.
Leah:
Yeah, I always kind of assume this buffer of like at least 10 to 20% under reporting. And that’s like on the good side where someone is like intentionally trying to do their best.
Aidan:
Yeah. And we’ve only spoken about one study there, but if you look across all of the research on reporting of calorie intake, it does come out that way where it’s like, it does make sense to have that 10 to 13% buffer on average. So I would look at things that way. So moving on to other areas of this, what could explain other aspects of this? The first one that I’ll go over is just inconsistent intake. It’s a super common thing.
A lot of people might do like I’m just going to use an example because there’s hundreds of examples of what this could look like but a classic example this could be tracking or consuming fewer calories five days of the week and then on the weekend not tracking potentially having higher calories maybe there’s a few snacks etc that are added in or whatever and it’s like the number that you’re tracking is different to what you are doing on average because of the inconsistent intake so like that’s a super common one like just putting it out there but most people aren’t robots eating the same thing every single day and that kind of needs to be factored in with stuff like this too.
Leah:
Yeah, which kind of leads on to our next point and that’s people that are not tracking or generally just don’t have a great awareness of intake and this to a certain extent can come back to under reporting kind of, but even from a not tracking perspective. So without tracking or having some way to kind of estimate your intake, it’s really hard to be sure of what you are actually doing.
I think like a very common example is someone who just tries to improve dietary quality, right? So like they just want to eat healthier and wanting that to lead to weight loss, where sometimes it will. Sometimes those changes will end up with you being in a caloric deficit, but not always. So without having some numbers around it, it’s really hard to kind of hone in on that. It’s also super common for people to just miss stuff. So whether that’s tracking or someone on a meal plan,
It’s that kind of cliche of not tracking those extra bites and sips and grazing across the day that can really lead to quite a large amount of underreporting or just again, not having this awareness of what you’re actually doing. Because for most people, we will be aware of what we’re doing consistently, but it’s all those things in between that we do mindlessly and really adds up at the end of the day and can be completely kind of ruining your progress.
And this also happens with people just genuinely making mistakes with tracking. I don’t do a ton of tracking with my clients, like people utilising MyFitnessPal. I think you probably do a lot more than I.
Aidan:
I would say about 10% of my clients. Okay. It’s not heaps.
Leah:
Yeah, I’d say probably five to 10% as well. So it’s not a lot, but when I’m looking through a MyFitnessPal record, even for people that think they’re tracking really, really well and super accurate, like I’ll look through and go, okay, now there’s actually a bunch of mistakes in here and places where we’ve lost quite a bit of accuracy that is going to lead to that very significant under reporting, then having a discrepancy between what we think we’re doing and what we’re doing in reality.
Aidan:
Yeah, a line that I add on that, like when I am working with somebody who’s tracking, particularly if they’re new to tracking, I try to do this to try to relate in a little bit, but like when I first go into nutrition, I’d like to think I’m relatively switched on. I tracked for about eight months on and off to start off with. I bring up the switch on thing because it’s like, I care about nutrition, I was trying relatively hard. But one of the things I didn’t care about when I first started tracking was raw weight versus cooked weight. Yeah. And I remember the main one that comes to mind is chicken breast, like in particular, I kept putting in the cooked weight for chicken, regardless of whether it’s raw or cooked, that is 30% difference. That’s 30% different in terms of protein intake, but also calorie intake.
That’s the only quote on quote mistake that I see that comes to mind when I first started tracking, but it’s like, hang on, I tried for like, eight months, relatively switched on, cared about nutrition. And there was that mistake in there. It’s a big mistake, granted, but it’s like, I don’t think there was many other mistakes or anything like that. But I use that being like, I think it would be interesting to make the assumption that particularly if you had less experience than that with tracking, that you have absolutely no mistakes in your tracking whatsoever. And then even if you did, there’s a bunch of other things that could come up as well.
Leah:
Yeah, there’s the, I guess the variables that you can control to a certain extent like cook versus raw and not using generic data and just trying to be as accurate with brands and stuff. But there’s also things like discrepancies in food labels where like there can be a discrepancy of like 20% from food labels. And obviously that’s not something that you can control.
It’s also not often a core reason why someone is significantly underestimating their intake or leading to confusion. But I think it does highlight that there are just so many variables that go into doing this accurately that can make it a bit of a minefield.
Aidan:
Yeah. So we’ve spent here’s a time going through like maybe calorie intake isn’t as low as you necessarily think it is. But I have another one that’s cropped up a fair bit that I want to talk about and it’s patience or lack of patience. Just speaking with clients, a lot of the times in Instagram DMs as well, like a lot of people will be like, I’m doing this, but it’s not working. Sometimes people are genuinely on the right track and doing the things that will make them see progress over time, but they could be misled by like scale fluctuations.
Example, somebody could be in a calorie deficit is large enough for them to lose half kilo body fat per week. So theoretically in two weeks they’re down one kilo of body weight in the form of body fat, but maybe they have had their water weight glycogen weight, food weight increase by more than one kilo due to other reasons. Like a classic example, particularly if they’re not weighing super frequently, but like a classic example could be like they’ve been in that deficit and then one day they have gone out and they’ve had something that’s high salt, decent amount of food volume.
Maybe it’s higher calories for that one day as well, but their weekly average has put them in a deficit and they feel like they step on the scales and they’re one and a half kilos up. And in that case, it’s like, no, what you’re doing is working. Like if you just kept that trend going for 10 weeks, you would be in a great place and you would have seen great progress. Sometimes literally just doing the same thing over is the key. Don’t take that too far though. Like if somebody was like, no, I’m six months in and I haven’t seen progress. It’s like, no, no, no, no, no, you should have made changes there. There is a surprising amount of people who have been doing something for less than two weeks and they’re like, I need to make drastic changes. It’s like, no, you could have just kept doing the exact same thing and seeing great progress.
Leah:
Yeah, I see that a lot in people with a menstrual cycle where we obviously have this like amount of water retention fluctuation over your cycle where a lot of your progress can be hidden for like two to three weeks of a month and then it drops down. So like sometimes it is just about holding out and then also seeing your trends over time rather than just like these kind of very random weights. Like an example, I was working with a client and they’re like, yeah, I’m not seeing any progress. Like I’m just feeling very frustrated. We had to look at all their weight data and we started taking weekly averages from that. The trajectory over time was like three to 400 grams of weight loss per week on average.
So I’m like, no, you are making progress. It’s just these kinds of big fluctuations here and there from like eating out or menstrual cycle that’s like confusing you. Moving on to the next topic. So we realistically, we do not have evidence of anybody not losing weight on really low calories in controlled settings. I think this is an important part of this discussion because a lot of people have this amount of self-doubt when it comes to this topic. They’re like, I’m on really low calories. I’m not losing weight. Like, is there something kind of wrong with me that is outside of underreporting or kind of having a general lack of awareness of what we’re doing?
So I personally use this to reframe things in that besides the just the theoretical sides of like how the body works, we can literally just look at the evidence and go, you this can’t be the situation in that you’re not so low calorie that you’re not losing weight. And that’s the reason because we’ve never seen that in research. So either you’re a freak anomaly or this is just not the case. And the second thing is far more likely if starvation mode was a thing that existed to an extreme level.
We wouldn’t see people starving to death because our bodies would just hold on to this weight as soon as we entered a very low-calorie diet. But if we looked at studies where they had people on 800-calorie diets, so a huge, huge deficit, we would see these people just not losing weight. But that is not what we see in practice when they are in these controlled settings on these very low-calorie diets they always lose weight.
Aidan:
Yeah. And it’s harsh, but like that freak, like freak out like kind of thing you talked about. It’s like, if that existed, there are many people who would love to study that. It just has not come. It’s harsh, but in a way it seems harsh, but then it’s also like, This is really good because it takes a bit of a handbrake off. It’s like you don’t need to be on your own head about being like, is the reason I’m not losing weight because I’m on two low calories. Cause it’s like that, that’s just never been found. Like that’s never been found in the research. There’s many downsides are going to low calories, but lack of weight loss isn’t one of them if it’s consistent, et cetera.
Another thing that will pop up that is worth talking through is medical conditions. The most classic one that I will see on if I ever see like an Instagram post or anything like this, go semi-viral on this topic. Instantly there will be comments about medical conditions being like, that’s an exception to calories in calories out. My response to that would be medical conditions don’t break the rules of calories in calories out. They just influence the variables. It is a real thing. It does play a role here, but it’s not like the rules are broken. It just fits into this model in a different way.
The best example of this is hypothyroidism. So hypothyroidism can lead to reduction in metabolic rate. This makes a lot of sense. It’s because the body doesn’t burn calories for no reason. The body is burning calories for purposes. The thyroid influences a lot of variables in the body. It helps control a bunch of functions. If the thyroid is downregulated, these functions are also downregulated. The body is suddenly spending less calories on these functions.
That often comes on side with a lot of symptoms. For example, if the body is spending less calories on digestion, then digestion will be slower. This is partly why hyperthyroidism can lead to gut issues like constipation. Brain fold can be a thing. The body can be spending less calories on that. People can feel more fatigued. Core body temperature, like people will feel a little bit colder because the metabolism, it like quite literally quite burning, like it does actually warm us up a little bit. So if it’s not functioning to the same degree, we feel a little bit colder.
This is partly explaining the symptoms and the reduction in calorie expenditure. But adding another layer of context to this, in the research I’ve seen as much as a 25% reduction in resting metabolic rate due to hypothyroidism, you can look at that number from so many angles. One angle you can look at it from is, that’s a real reduction. Like personally, like I know this is resting metabolic, like it’s just resting metabolic rate, it’s not total daily energy expenditure.
But like if I had to eat, 15 to 25% less, the hunger I’d experienced from that is real. Like the lack of calories and the downsides of that, like that’s real. But then I’d also be quite unquote spinning my wheels and not seeing progress. Like I would be in that scenario, it’s like I’m on lower calories than expected and not losing weight. But theoretically, I could still go lower than that. That’s not, I’m not saying you should do that, but looking at that 25% number from another ring.
That’s the most that has been reported in research that I’ve seen, like that’s coming from a review that looked at all of the research up to a certain date on hypothyroidism. That’s the most that has been seen there. But you could look at that from other angles and be like, well, that means most people by definition would be less than that 25% number, but these sample sizes are not huge. They’re very, very likely people out there in the real world who have more than a 25% reduction.
But addressing medical conditions for non-weight related reasons, makes a lot of sense. Like those symptoms, like the bigger the reduction in energy expenditure, probably the worse the symptoms are going to be. I’ve only used hypothyroidism as an example, but you could look at a bunch of medical conditions and make similar things about that. Like that becomes a very, very big topic. One final thing, just doubling down on the hypothyroidism thing is if somebody did have thyroid medication that brought their thyroid back into the regular range in terms of their hormones, their thyroid hormones, it reverses that reduction.
It suddenly gets near normal. I could go into detail about why it’s not exactly normal, but it does get near normal once it’s reversed. So like going deep on that, the medical stuff could be an entire podcast. The simplest way I’d look at it is it influences the variables in multiple ways. Like one is it can literally change energy expenditure, but two, it can also make it difficult for all the other reasons. Like if somebody was living in hypothyroidism, for example, it’s like, it’s harder to do all the other stuff that helps with all this too.
Leah:
Yeah, definitely adds barriers, but it’s not like if you don’t go, if you go lower calorie, you’re going to see results, obviously.
Aidan:
Yeah. And it’s not like it completely changes the game where it’s like, no, to lose weight. What I have to do instead of focusing on calories is focus on this instead. Like it’s, it’s still the same, same rules. Same principles apply.
Leah:
And a good segue from that is talking a little bit about metabolic adaptation and low energy availability, which is something that we’ve touched on quite a lot over the course of the last three years. But metabolic adaptation is essentially the phenomenon where resting energy expenditure reduces by more than what a formula would predict while dieting. And this is due to a lot of down regulations by the body as a way to conserve energy. So your body recognises that, hey, we’ve got less energy than we need coming in. There’s probably some processes that we can down regulate to just try to conserve a bit of energy.
So to a certain extent, it’s your body kind of like fighting against it, but it’s not typically a massive difference. So it’s not like your body will conserve so much energy through this downregulation that it cuts away the entire deficit on its own. But in states of low energy availability, there obviously have been documented cases of people being on lower calories than what is predicted to be their maintenance and then still not losing weight.
A good example of this is those that fall into the category of like hypothalamic amenorrhea where there is a loss of menstrual cycle, which is again goes back to those down regulations in certain processes as your body kind of fights against that low energy availability. And then these people not losing weight at a calorie amount that they would generally expect to have lost weight. So from here, there are a couple of things worth noting.
Firstly, weight loss typically precedes this issue. So it’s not like you enter this stage immediately as soon as you get into or start a lower calorie diet. It’s not like this kicks into gear straight away. There typically has to, well, there definitely has to be a deficit that has been present. There is weight loss that has occurred to provide the stimulus for this downregulation. So it’s not like you go one day of maintenance, the next day you’re on 1200 calories and immediately there is this direct metabolic adaptation downwards. So it’s not how it works.
And realistically, in these situations, there is still maintenance calories. It’s just a slightly lower number than what we would have predicted. So if these people went lower calorie than that, they would still lose weight. This is not always a good idea, particularly in the case of someone losing their menstrual cycle. Like I would obviously recommend that we hop out of a deficit. We rectify that situation. Change the course of this metabolic adaptation and reverse that and then look at leaning out if that’s still part of the process. But at the end of the day, if you go lower calorie, you will lose weight. So it still comes down to calories in versus calories out. It’s just metabolic adaptation can make that a little bit more confusing than I guess what it appears to be on like face value.
Aidan:
And looking at the technical definition of metabolic adaptation, that is in relation to just the resting of metabolic rate. But if we extended it and broadened it out, we’d also include non-exercise activity thermogenesis, so like informal movement as well. So typically, if we were in that side where things had been downregulated due to metabolic adaptation, the vast majority of people will also be a little bit lower energy, they’ll move less, a lot of incidental movement reduces people if they’re not tracking their steps would typically get less steps. This is a very well documented phenomenon. But I want to go through the fact that like if somebody say had hit a plateau, it’s rarely just one of these things. It’s in our nature typically as humans just to be like, this is what the cause of the plateau is and point to one thing.
But when you hear all of this, you’re like, okay, what if there was like 100 to 200 calories down due to metabolic adaptation? What if there was like 100 to 200 calories down from a reduction in informal movement due to all of these things that occur. Then this is a separate topic, but what if there was a little bit of inconsistent intake due to an increase in hunger in response to being on lower calories, there’s a bunch of things you can do. And suddenly add it up and you’re like, this is actually a huge difference that could be explaining why weight is stable, rather than just trying to pinpoint one particular cause. Yeah, it’s usually multiple things playing a role in this.
Leah:
As a bit of a summary or practical takeaway from this episode, I would like to say that if there is a concern that low energy availability is at play, the first move would be to essentially take the emphasis off fat loss for at least a little while. So increase calories, address that first, look at reversing metabolic adaptation, getting yourself to a good place of being able to then go into a deficit and see results.
Secondly, if there is a medical condition involved where we can take steps to address a reduction in metabolic rate or reduction in calorie output, addressing that where possible absolutely makes sense. Like Aiden said, you probably want to address this for a multitude of reasons in terms of how you feel and your medical management of a condition. But as part of this discussion, it also makes sense to address it from that point of view as well so that your energy expenditure is more near what is expected.
If neither of those things seem to be a factor in your particular situation, then you have still a couple of things you can do. So we’re looking at either increasing energy expenditure or simply reducing intake. So we could increase our energy expenditure through things like more formal structured exercise. We could also look at doing more just informal movement. So something that a lot of people use these days is like a step count or even just making sure that they like take the stairs instead of the escalator, like kind of doing all those little bits and pieces. Or like I said, it can be your actual training, adding in more sessions.
Energy intake can also be reduced. So we can either just plan to eat less. So maybe we’re aiming for a lower calorie number. If we’re working off a meal plan, okay, we just reduce the amount that is on the meal plan. We could also look at improving consistency. So if you’re someone who is great Monday to Friday, and then weekends are a bit of a free-for-all all, okay, maybe that’s the focus. So just making sure there is more dietary adherence in general can be a great way to just be more compliant and reduce your intake.
In general though, if you’re not sure where to start, I think that’s a good opportunity to reach out to a professional or a dietitian and allow them to look at your situation and go, okay, I think X, Y, and Z are probably playing a role and then having a good path forward where things seem a little less confusing. So sometimes that is the play.
Aidan:
Hopefully that’s a pretty good summary, but if anyone does have any questions or anything like that, our DMs on Instagram are always open. We’re easy to find on Instagram. So send us a message if you have questions. But apart from that, this has been episode 158 of the Ideal Nutrition Podcast. If you haven’t left a rating and review, we’d massively appreciate that. But apart from that, I hope you enjoyed this episode.