We have often surmised that we probably aren’t very good at guessing how many calories we are consuming. 
We think this, because our ability to regulate what we have eaten in the past has clearly been ineffective, because our eating has caused us to gain weight. We clearly can’t easily determine whether the food we have consumed is the right amount of calories for our bodies physical requirements.
There are lots of potential reasons for this, and there have been lots of scientific studies that explore this and back up these thoughts. The Office of National Statistics (ONS) carried out a study in 2018, to look into how people report the amount of calories that they consume, and whether it accurately reflects actual calorie consumption.
The reason for this study was to understand why generally reports of calorie consumption were reducing, but the population’s weight, and incidences of overweight and obesity, was increasing. So there had to be a reason why. And it couldn’t just be that we were less active as a nation, because the drop in energy expenditure, did not equate to the rate of weight gain in the general population.
This study found that on average British people under estimate the amount of calories consumed, and actually take in 50% more than they think they do. In the ONS study 4000 people reported calorie consumption as part of a diet survey and it revealed some interesting findings.
- Men reported consuming 2065 calories a day on average, but actual consumption was 3119
- Women reported consuming 1570 calories a day on average, but actual consumption was 2393
- Obese and overweight people under estimated their calorie consumption by a greater proportion than those who were a healthy weight, although there was still under-reporting in this sector.
So why do we under-report?
The individuals taking part in the survey were general members of the public, who were asked to participate. They weren’t picked because they were trying to lose weight, or were already counting calories as part of their lifestyle. Therefore, it is likely that they weren’t particularly meticulous about the calories they were recording and they were probably making an estimate of their consumption. The Chief Nutritionist at Public Health England, Dr Alison Tedstone said about the survey, “Under-reporting of intakes has always been a feature of all diet surveys. Some people forget what they’ve consumed and some change what they record knowing they are part of a survey.”
Does this sound familiar?
Aside from forgetfulness, or artistic licence on recording, there are other reasons why calories might be under-reported.
Other studies on behaviour suggest that the increased level of under-reporting in overweight and obese people, is correlated with their portion sizes, and an underestimation of these, in that bigger people, tend to eat bigger portions of food, and therefore underestimate how much they are actually eating. There are also correlations with people who report that they are trying to lose weight, and a greater underestimation of calorie consumption.
So, it’s fair to say that if we are overweight and trying to lose weight, the statistics suggest that we aren’t very good at guessing or estimating our calorie intake.
If you think about it – you might free pour yourself a ‘250 calorie’ bowl of cereal in a morning, or as a snack, which in reality, if you actually weighed out the cereal and measured the milk, could be nearer 500 or even 600 calories.
Why do we underestimate? Is it a conscious thing? Are we trying to make ourselves feel better? Or are we just avoiding the truth about what we are actually eating? Is it because deep down we don’t want to stop eating? Ultimately, if we have a goal of weight loss, we are going to have to face facts, and make some changes, because if we always do what we have always done, we will always get what we have always got!
The Food Environment
Further research suggests that as human beings, we generally aren’t very good at regulating our appetites either. This stems from our hunter-gatherer days when food was sparse, and we ate and ate and ate when we could, because we didn’t know when the next meal was coming. So, our evolution hasn’t caught up with the evolution of the food industry and the abundance in which food is now available to us.
We now eat out of the home a lot more frequently than we ever have, and this also gives us less control over the amount of calories we are consuming. Chain restaurants and cafe’s do, in the main, give us calorie information now, but smaller outlets don’t. There’s a multitude of reasons for this – the business is too small, and doesn’t have the resources to work out accurately how many calories are in their potentially frequently changing menus. Larger chains have huge teams and plenty of money to pay for testing to back up their claims on how many calories are in their products, they have strict portion control on assembly of their dishes giving them the ability to more accurately calculate the calories. Smaller operations are generally one- or two-man bands, and just haven’t got the time to sit down and work out the calories of every single thing they make, as well as serving the customers, going to the cash and carry, doing their accounts, and everything else that comes with running your own food business.
Further, we have no control over the method of cooking in the majority of food outlets that we visit, and therefore have no control over the amount of fat and the types of ingredients used. So even making a good guess could be way out, depending on where and what you are eating.
Increases in snacking
There is also a growing body of evidence to suggest that our snacking habits greatly contribute to under-reporting of calorie consumption.Particularly if we snack mindlessly, with little thought for whether we need the food – it’s just we have seen it so we are going to eat it. For example, one study placed sweets either within reach in a transparent container, requiring no effort to bring them to mind and obtain them; or out of reach in an opaque container, requiring some mental effort to remember their existence and access them. Under-reporting increased when eating did not require conscious effort and attentive action. There lies a clue – out of sight, out of mind – if you can’t see it, you will probably eat less and you will definitely be more aware of what you have eaten!
It really is all in our minds!
An Australian study looking at behaviour related to hunger asked people to assess their hunger levels after eating an omelette. The people who were told that they had been fed a two-egg omelette reported significantly higher hunger levels than the people who were told that they had been fed a four-egg omelette — even though they had all been given a three-egg omelette to eat.
A BBC survey asked sets of twins to drink a meal replacement shake. One half of the twins were told the shake was 200 calories. The other half were told the shake was 400 calories. They had all consumed a 300 calorie shake, and those who had been told they were having a 200 calorie shake reported higher hunger levels than their twin who had the 400 calorie shake.
So, our beliefs also have an impact on our perceived hunger levels – it really is all in our minds!
Over-estimation of calorie burn
Another place we miscalculate our calories is during exercise. We have discussed this frequently in the past few weeks, that we can’t exercise our way out of a bad diet, but we know this is a common misconception. A half hour HIIT session is approximately a 200 calorie burn, an hours run is approximately a 600 calorie burn, yet we reward ourselves with food, that far outweighs that burn, thinking we have earned it!
Play this to our advantage!
The conclusion of the behavioural insights team, who wrote the final report on the ONS survey, was that the UK should implement policies to reduce calorie consumption, rather than focusing solely on increasing the physical activity of the nation. And I think it is fair to say, that we agree with them. We know that we need to decrease what we put in our bodies to achieve our goals, and from what we have learned throughout this article, we can put some plans into practice to help with this.
Scientists reckon that if we are more thoughtful about what we are eating, and savour every morsel, rather than gorging ourselves just to get through the massive portion, will mean that we actually eat less. There’s a reason for this, if we eat slowly, our brains will catch up and pick up the signals that we are getting fuller, and also if we really think about all the flavours that we are tasting our senses will pick up the signals that we are eating, and feedback that we are becoming fulfilled. This is demonstrated by a French study on school children. 42 French school children were invited into a lab and split into two groups. One group was asked to imagine just how wonderful it is to eat a delicious chocolate brownie. Imagine the texture, smell, crunch and all the delicious flavours. The other group was told nothing.
Then each of the children were presented with a huge assortment of delicious brownies, each cut to a certain size to regulate the portions. Despite having spent just 10 minutes thinking about what eating the brownies would feel like, the kids who had thought mindfully about eating them actually ate less overall than those who didn’t.
Another study asked 190 hungry Americans to split into 2 groups. The researchers gave them one of two sample menus for a dinner. One menu just listed the food with little description. The other menu contained flourishing descriptions, much like you would find in a fancy restaurant – describing the aromas, subtle flavours and aftertastes. After eating, the results showed that the people who had been given the more descriptive menu ate slower and consumed smaller portions overall.
Another element of eating mindfully, is to consider when you start to feel full. In Japan, the Okinawans follow a teaching that instructs people to eat until they are 80% full, called ‘Hara hachi bun me’. The result is that the general population’s weight reflects this. The typical body mass index (BMI) of a person over 60 in Okinawa is about 18 to 22, compared to a typical BMI of 26 or 27 for adults over 60 in the United States. And this has an effect on their longevity too, as Okinawa has the world’s highest proportion of centenarians (a person over 100 years old), at approximately 50 per 100,000 people.
What can we do?
Therefore, in conclusion we can do a number of things to help curb our calorie consumption and ensure what we are eating and drinking is more in line with what our bodies need, and what we are trying to achieve.
- We should over-estimate how many calories are in the food that we eat out of the home – because we don’t know cooking methods, portion sizes and hidden ingredients etc. Some experts recommend adding an extra 40% to our estimations.
- We should check the packaging of foods where the calories are noted rather than guessing how many calories are in something.
- We should write down our food choices and calories as soon as we eat them (or before) to avoid ‘forgetting’ what we have eaten.
- We need to be honest with ourselves and write everything down, not just what looks good in our food diaries. Stop kidding ourselves.
- We should try and connect more with our senses when eating, to help us feel fuller quicker. Think about the flavours and textures, and how much we are enjoying eating the food, instead of shovelling it in without any thought.
- We don’t need to buy those snacks in that are going to do us damage – if we know we eat them because they are there – don’t buy them, don’t give yourself the temptation. Remember, out of sight, out of mind.
- We should stop rewarding exercise with food.
- We should stop eating when we are 80% full, to allow time for our hunger hormones to catch up and tell us that our tummies are full.
With a few careful tweaks, we could start to see even more success than we are already having. Knowing why recommendations are made, and that there is evidence behind it will hopefully help you to see why it’s worth having a go at some of these techniques.
This week, have a go at some of these things, but most importantly bear in mind how accurately you record your own calorie consumption, be honest, and the changes will undoubtedly start to happen! If we keep guessing we are essentially playing roulette with our chances of success. Be accurate and guarantee that success!