Key Topics Covered

Man with tape measure around waist.

Let’s start with a brief background on why ‘calories in, calories out’ works:

  • The body is partly made up of calories

  • Every day we eat a certain amount calories and burn a certain amount of calories

  • Moving target – we don’t know how many we have burned in everyday life

We will begin with the common issues, then we will talk through scenarios where it actually might be the case that you are on lower than expected calories and not losing weight. Then we will talk about what to do. 

Research on Underreporting

  • Whilst not a popular topic of discussion, we really need to talk about under reporting.

  • Practically all the research looking at this has found that people typically underreport their intake significantly.
  • I want to start here because it also changes how we think about this topic. 

  • Example: If a friend says “I’m eating 1200kcal per day and not losing weight” based on the stats, rather than the individual situation, it makes sense to make the assumption that they aren’t actually eating 1200kcal.
  • When their metabolic rate was measured it was within 5% of predicted values on average.
  • When their intake was measured vs what they said they ate, it was found that on average they underreported their intake by 47% on average.

  • Two major things stand out. One participant underreported by 80%. No participants got within 20%. To give an example, the most well known study on the topic got together people who had reported as diet resistant.
  • The participants had reported not losing weight on <1200kcal. 
  • The 80% one is crazy – and is super relevant, particularly when factoring in what people say vs what they might do.
  • But the fact that nobody got within 20% is arguably more relevant because it highlights how unintentional this is.

Inconsistent Intake

  • With that out of the way, let’s look at other areas:

  • Inconsistent intake is a super common thing.

  • For example: tracking or consuming fewer calories 5 days of the week, then not tracking and having high calories 2 days of the week.

Not Tracking or Having Awareness of Intake

Sometimes it’s as simple as not having awareness of your intake.

  • Without tracking intake in some way, it’s hard to be sure of your intake.

  • It’s also super common for people to miss stuff when tracking e.g. the cliche coaches say about not tracking bites and sips.

  • A lot of people genuinely just make mistakes when tracking too.
  • I’ve seen so many people who are SURE they are tracking accurately, and then their MFP is full of mistakes. 

  • Discrepancy in food labels is also a thing (20% rule thing).
  • Not that this is often a core reason why someone is underestimating their intake but it does show the number of variables that go into doing this accurately.

Lack of Patience

  • Sometimes people genuinely are on the right track and doing things that will see them make progress, but they haven’t given it long enough or are misled by scale fluctuations.

  • For example: somebody could be doing something for two weeks that leads to half a kg of fat loss per week, but have their scale weight remain unchanged because they gained 1kg of other mass e.g. water weight, glycogen or food weight.

  • If that person kept that trend up for another 10 weeks, they are guaranteed to lose a bunch of weight, since we can only store so much of that other stuff, plus it could have just been a random fluctuation. 

We Don’t Really Have Evidence of Anybody Not Losing Weight on Really Low Calories in Controlled Settings

  • This topic can seem confusing and sometimes cause a bit of self doubt. 

  • Particularly when you encounter cases where it seems like somebody is tracking everything perfectly.

  • The thing that I personally use as a reframe, beyond just the theoretical side of how the body works, is that we can literally just look at the evidence.

  • In research, we never see people on really low calories not losing weight, when all food is provided. I’m not even just talking about averages, I mean you can go and check each study and see the individual results of everybody. 

  • If this whole starvation mode thing existed to an extreme level, we would see it show up in some of these studies where they give people 800kcal per day type diets.

Medical Conditions

  • Medical conditions don’t break the rules of ‘calories in, calories out’, they just influence the variables

  • For example: Hypothyroidism leads to a reduction in metabolic rate. This makes sense because the thyroid plays a role in a bunch of functions. If it is down regulated, these functions are down regulated too. This results in fewer calories being burned.

  • In the research, a 25% reduction in resting energy expenditure is seen due to this. 

  • Addressing relevant medical conditions for non-weight related reasons is obviously important but I just wanted to touch on this topic and give an example of how it fits in. 

Metabolic Adaptation and Low Energy Availability 

  • Metabolic adaptation is the phenomenon where resting energy expenditure reduces by more than a formula would predict while dieting. 

  • This is due to down-regulations by the body to conserve energy. 

  • It’s typically not a massive difference, but it plays a role.

  • In states of low-energy availability, there have been documented cases of people being on lower calories than predicted to be a deficit and not losing weight.
  • For example: There is evidence of low energy availability due to loss of the menstrual cycle, while consuming fewer calories than expected for weight maintenance. 

  • Two things are worth noting here:
    1) Firstly, weight loss typically precedes these issues. The deficit had to have been present to provide the stimulus for the body to do the down regulation.
    2) Technically it’s a sweet spot still, if weight is stable. It’s just like having maintenance calories at a slightly lower number. If these people went lower calorie, they would still lose weight. I don’t think that’s a great idea all the time, but it’s worth being aware of. 

Reduced NEAT

  • Similarly to metabolic adaptation, when people are on reduced calories, they tend to conserve energy in other ways. For example, reducing informal movement.

  • This reduction in energy can add up over time.

  • It’s rarely just one thing at play. Often there is a combination of reduced energy expenditure from metabolic adaptation and NEAT AND a subconscious increase in intake for a variety of reasons. 

Summary

  • If there is concern that low energy availability is at play, the first move would be to take the emphasis off fat loss for a bit. I’d increase calories and address that first. 

  • If there is a medical condition involved, I’d take steps to address that, where possible, even for non-weight related reasons. For example: Addressing hypothyroidism through medication to bring levels back to normal typically results in energy expenditure returning to near expected levels.

  • If these points above are not factors, you have two options: 1) Increase energy expenditure or 2) Reduce intake.

  • Energy expenditure could be increased through more informal movement, or more actual training.

  • Energy intake could be reduced by either reducing the planned intake, improving consistency, or improving adherence in some way. 

  • If you just are not sure where to start but you are struggling with this, sometimes the best option is to have a dietitian or health professional go through everything with you and decide on a path forward.

Relevant Blogs / Resources  

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