One of the most common things I see in practice is that a lot of people feel like they are eating relatively low calories, but not seeing the weight-loss results they expect.
This can obviously be a frustrating experience.
Some people can lose weight easily while barely trying. Others can put a lot of time, energy and focus on it, while still not getting the results they want.
Unpacking this issue though, I want to provide some potential reasons why this might be occurring, as well as some solutions.
Obviously, none of this is individualised advice. Instead, it is just an attempt at highlighting the most common reasons and solutions that I see in practice, based on a combination of research, science, and practical experience.
Background on Weight Management from a Theoretical Perspective
The phrase “calories in, calories out” (CICO) is considered controversial.
Some people say things like
- “Calories are outdated”
- “CICO is oversimplified”
- “It’s not calories, it’s hormones”
- “We can’t easily measure our calorie expenditure accurately”
- “We can’t accurately measure our calorie intake, particularly since the amount of calories we ABSORB from foods is always going to be different.”
The one I agree with most is that CICO, at face value, appears oversimplified. But if you dig deeper, it is not simple at all.
Theoretically, if you burn more calories than you consume consistently for long enough, you WILL lose weight over time.
That is just a factual statement.
The reason for that is the body is made up of calories. 1kg of body fat contains around 7000kcal.
We only get calories externally from food. Calories are a unit of energy and cannot just be created from thin air.
Body fat is one of our storage forms of calories.
If we consume fewer calories than we burn, it HAS to come from somewhere. If we are not getting it externally, it must come from our internal stores. These stores include fat and muscle, which is why a calorie deficit leads to weight loss.
Unpacking Criticisms of CICO Further
I promise I will get into solutions after this section. I just want to double down on theory first, since the next sections do not make sense without this.
If you pay close attention to that last section, you will notice I say, “if you consume fewer calories than you burn.”
That is an important line.
This is part of why CICO is complicated. The calories out portion is NOT a static number. It changes. It is influenced by so many variables.
Unpacking the hormones criticism – Hormones are literally factored into the equation. Hormones change BOTH the calories in and calories out portions of the equation.
Thyroid hormones influence our energy expenditure. Decreased T3 and T4 could lead to lower energy expenditure.
Increased ghrelin can make you hungrier. This could increase the calories in part of the equation.
Hormones ARE part of the equation.
The absorption argument is also factored in. It does not break the equation; it improves it.
Almonds are the most common argument here. People point out that the research indicates we only absorb ~70% of the calories from almonds. Whereas for pure sugar, it is near 100%.
That is an interesting point. And if it was not factored in, it would be a valid criticism. But once you factor in that different foods are absorbed differently AND have an awareness that the difference often is not that significant (almonds are used because they are an outlier), it is no longer a valid criticism.
Also just because we cannot perfectly measure our intake/absorption does not mean that calories do not matter. It just means we are more estimating our intake than accurately tracking, no matter how hard we try.
CICO dramatically influences our weight – but it is not necessarily as simple as it seems.
Check for Medical Conditions
Medical conditions can potentially play a role in why it might be hard to lose weight.
It is often not the most common explanation, but it is worth ruling out.
Within this category, the most clear-cut example that I do see though is that you could have an underactive thyroid.
Since thyroid hormones are involved in so many processes in the body, an underactive thyroid can reduce energy expenditure.
Based on the research, it appears as though resting energy expenditure might be reduced by as much as 25%, although it is hard to get perfect figures for this.
If 25% is the maximum, most cases will be less than that.
Resting energy expenditure is only a portion of our total energy expenditure too.
But either way, say it reduces total energy expenditure by 10% as an example, this would mean you would require fewer calories to maintain your body weight.
You would have to drop calories slightly more than expected to achieve the weight loss you want.
Another option in the medical category could be PCOS.
A lot of women with PCOS report that they find weight loss harder. The research on this topic is mixed, but one study identified the potential for a 14-40% reduction in basal metabolic rate.
This would present similar challenges to the thyroid hormone situation.
Having empathy here, even a 10% calorie reduction makes things harder than you would expect. It reduces dietary flexibility and also likely increases hunger and desire to eat by more than 10% in most people.
These are just two examples. Neither necessarily PREVENT weight loss. But they do make it harder. And both are worth identifying regardless since beyond weight loss there are a LOT of reasons to address them.
Another option worth being aware of is lipedema. It is beyond the scope of this post since it is a complex condition – but it can lead to body fat gain even while on relatively low calories. It is certainly another option worth looking into.
Test Resting Metabolic Rate
Having a slow metabolism is a common assumption that you could make if you are in this position.
A slow metabolism would mean a lower energy expenditure. The calories out part of the equation would be lower, making it harder to create a calorie deficit.
Do you feel like that is a possibility for yourself?
If so, you can actually test your resting energy expenditure (also known as resting metabolic rate).
A lot of places offer this service utilising a Calorimeter. It is a relatively short procedure, and it can confirm whether or not your suspicion is accurate. It costs money but is worth it for some people.
Having a lower-than-expected resting metabolic rate is a possibility.
One extreme example of this in the research involved the Biggest Loser Study. This study identified that resting metabolic rate was an average of ~500kcal below what would have been predicted by a formula 6 years after the show.
This is not representative of what dieters normally experience though. It is actually a massive outlier in the research. But I share this study to highlight that it is possible that your resting metabolic rate could be lower than predicted.
If it is lower than predicted, this helps since it allows you to identify how much of a barrier you need to overcome.
If it is not lower than predicted, that is also useful information since it helps identify that there are other areas to focus on instead.
Monitor Water Retention
While a calorie deficit leads to weight loss over time, it is possible for it to be masked by water retention.
In some cases, there can be medical causes of water retention.
In other cases, it can be related to food intake.
Using an example:
- Six days a week you could be in a large calorie deficit. One day you might be in a small calorie deficit (or a surplus). On that day, you might have a lot more food, carbs and sodium. These can all lead to a quick spike in weight due to food weight, glycogen and water weight increasing.
In that example, you might be in a deficit the entire week. But your weight could fluctuate so much that you think you are not losing weight.
But if you repeated that cycle long enough, you would be losing weight consistently, regardless of these spikes.
With medical conditions, there can be a lot of water retention that masks the calorie deficit. Fat loss could be occurring, but it might not be showing on the scale.
Outside of medical conditions, I would advise mostly ignoring weight fluctuations. Instead, I would focus on the average scale weight over time, rather than individual measurements.
If the average is going down over a period that is at least multiple weeks long, it would be a calorie deficit. If it is not going down, it is unlikely there is a deficit in practice, outside of more extreme cases.
Focus on Consistency
Another possibility to consider is consistency.
A lot of people will have phases where they crush it with their nutrition, followed by phases where it is not so great.
Potentially nutrition is good Monday to Thursday, but then not so good Friday to Sunday.
Or maybe it is good for 2-3 weeks, followed by a not so good 2-3 weeks.
I am not really going to speculate much here. There are a lot of possibilities.
A curveball in this discussion is that when people say what they eat or the number of calories they are consuming, on average they underreport significantly.
Instead of having an opinion, or making assumptions, I am just relaying what the research shows.
Almost all the research on the topic identifies that on average, people underreport by >20%.
The most relevant study on the topic (in my opinion) got together a group of people who identified as being diet resistant. These individuals personally felt like they had not been successful with weight loss on low-calorie diets.
On average, their resting metabolic rate actually worked out to be within 5% of predicted values. This is crazy considering you would expect this group to be far more likely to be significantly different than most people.
In terms of reporting, what people said they ate averaged out to be 47% (1053kcal) less than they actually ate. One person underreported by 80%. The closest anybody got was 20% under.
The 20% number stands out to me. Nobody was within 20%.
So far, this section has just been relaying facts from research. Now I will include personal interpretations:
- On average are not good at communicating what they eat. Is it forgetting what they eat? Lack of accuracy in tracking? There are a bunch of reasons. Either way, it happens.
- Because of this, if somebody looking to lose weight says “I’m eating X calories” I automatically estimate they actually average >20% more calories than what they say on average. You can debate this assumption, but it is the most common conclusion based on what the research indicates.
There are obvious exceptions to the third point. But understanding this concept is helpful. It might be relevant for how you assess your own nutrition. It also allows us to understand situations more based on what other people say about their own nutrition.
Check Tracking Accuracy
Whatever system you are using to estimate that you are consuming low calories, it is worth checking the accuracy.
If you are eyeballing food, for example, it could be worth weighing food occasionally using kitchen scales and confirming it is the portions you think it is. It is not uncommon to be consuming >50% more calories than you think in a meal just due to this.
If you are tracking calories, it is worth double-checking your accuracy.
Are you choosing the right options in MyFitnessPal or the app that you use?
Are you sure you weighing your food raw instead of cooked? Raw is a more accurate way to weigh since cooking food changes the water content.
An increase/decrease in water weight does not change the calorie content. But if you track it in an app and just put in the weight, it will give you a different calorie number even though it remains unchanged.
Are you tracking EVERYTHING? Do you track every bite of food? Do you ever snack without tracking? Do you track coffees? Do you track the oil you cook in?
Once again, I am not making assumptions. I am just trying to highlight common issues people face and ideally a couple of them are relevant for you.
Another thing to consider: Just because a food label says a certain amount of calories, does not mean it IS that amount of calories.
A safe assumption is that the calories of food with multiple ingredients has a 20% margin of error.
This sounds large and could be considered excessive by some, but in practice, it is an idea that works well. It also helps keep an open mind since it changes the thought process from:
“I AM eating X number of calories” to, “I THINK I am having ROUGHLY X number of calories.”
That distinction is helpful. Assuming you track 100% accurately can lead to issues regardless of how much effort you put into it. Assuming there is some margin for error makes it easier to adjust as needed.
Allow for Error in Estimations of Energy Expenditure
We have a calorie calculator on this website. Obviously, we think it is helpful as a starting point for estimating energy expenditure.
But the issue a lot of people run into is that they take estimations as 100% accurate.
No formula will be perfect for YOU. You are an individual and have individual energy requirements that change daily.
A lot of people say “I am in a 500kcal deficit per day” because they used a calorie calculator to estimate their maintenance calories and then aimed for 500kcal less than that number.
An estimate is still only an estimate. It is a good starting point, but you need to adjust based on what happens in practice.
If you were in an estimated 500kcal deficit and were not losing any weight after multiple weeks/months, then it was not actually a 500kcal deficit. Either there were issues in the accuracy of your calorie intake estimations or there were issues with the estimation of calorie expenditure.
It makes sense to use a calculator as an estimate to start off with. But do not get attached to it. What happens in practice is far more important.
Consider a Diet Break
Another option to consider is to take a diet break.
A diet break is a phase where you intentionally eat maintenance calories.
Most diet breaks go for 1-4 weeks. But you can do it for however long you like.
Theoretically, if you have been eating in a deficit, a diet break can help with the following:
- Reversing metabolic adaptation
- Reducing hunger and desire to eat
- Reduce the restriction that is associated with dieting
- Help practice what eating at maintenance calories feels like
From a psychological perspective, this could be helpful.
From a physiological perspective, it would only really benefit you if you were actually in a calorie deficit. If you were not losing weight, you would have been at maintenance calories already. Technically that would have been an unintentional maintenance phase.
One exception to this could be when somebody is in a specific state of relative energy deficiency.
In some cases, it is possible for somebody to be on low calories in relation to their requirements, exercising quite a lot and also STILL not losing weight.
This state of low energy availability can be evidenced in females by a loss of menstruation due to a lack of available calories to be utilised. The body downregulates a lot of non-essential processes to try to preserve calories to be used for more urgent demands.
Even in this case, it is a bit of a rare occurrence requiring a specific range of calories. The body can only downregulate so far. It cannot switch every process off. So technically while going even lower calorie than this amount would be silly, it would still result in weight loss.
Somebody could potentially raise calories without their weight going up significantly in this case. Processes in the body could be upregulated. This upregulation would lead to increased energy expenditure, therefore raising maintenance calories higher.
In a variety of situations, raising calorie intake for a phase can help prepare you for future fat loss phases.
Consider Decreasing Calorie Intake
Now comes the obvious one – but it still needs to be said.
Sometimes you just need to reduce calorie intake.
There are heaps of explanations mentioned above. But if we are looking for solutions, reducing calorie intake is one potential solution.
Some red flags of being on excessively low calories are:
- Extreme hunger
- Frequent illness/injury
- Poor training
- Sleep issues
- Disordered eating thoughts
- Loss of menstrual cycle (if relevant)
There is a really long list beyond just this. But it is worth being aware of the red flags. Because what if you are not experiencing any of them? If you are not experiencing any red flags, you might have room to drop even if you think you are on low calories already.
If you ARE experiencing them, then it is worth contemplating whether dropping is a good idea. It likely is not a good idea if you are experiencing negative effects from being on low calories.
Consider Increasing Calorie Expenditure
Another obvious one that needs to be said is to consider increasing energy expenditure.
One example could be to exercise/train more.
If you are overtraining, or on the border of overtraining, I do not encourage increasing further.
Overtraining creates a whole other set of problems. We do not want to do that.
But if you are currently exercising less than the optimal amount, it could be worthwhile increasing.
As a side note, building muscle can raise resting energy expenditure a little bit too. It is not a massive increase in most cases, but it can make a bit of difference.
Another option is to increase your step count. This is a simple way to increase calories burned with minimal effort. If you do <5000 steps, it could be worth raising it to 5000-1000 steps for example.
I often like to use extreme examples as thought experiments. And there is one that is relevant here.
If you were to eat ZERO food for the next month, assuming you survive, would your weight go up or down?
It is not a trick question.
Your weight would certainly not be going up. You would not be gaining body fat or muscle, since there is no surplus of calories available to be stored as those.
It would go down. Your body would be pulling from fat stores (and muscle most likely) to fuel its functions where possible.
When we work backward from that, we can agree that SOME level of low-calorie intake is going to result in weight loss.
While it is not a simple process, we do know that CICO works. The tricky part is creating that calorie deficit in practice. There are heaps of options. It is about finding the one that is practical for you to implement.
As a caveat though, weight loss does not necessarily need to be the goal. And it is not always something that is beneficial for you. In some cases, the pursuit of weight loss can cause more harm than good.
It is really a case-by-case basis.
In this post, I have just tried to highlight reasons why weight loss might not be occurring at the rate you would expect.
It is a broad topic though. Many of these points will not be relevant for you. Some might be. Ideally, you just pick through and focus on the things that could be helpful for you, if there were any.