How accurate is calorie tracking anyway?
Conventional wisdom says if you want to lose weight you just need to ‘maintain a calorie deficit’.
‘It’s all about calories in vs calories out,’ they say.
It all sounds so seductively simple!
But the reality couldn’t be more complicated.
However, the numerous factors on both sides of the “calories in vs calories out” equation are incredibly complex.
As you will see in this article, it’s impossible to manage either side of the energy balance equation either precisely or accurately.
So is there any value in tracking your food?
Is it worth the effort?
When is tracking useful?
When is it a waste of time?
First, let’s first look at the “calories in” side of the equation, which is arguably the simplest because it focuses on the things outside the body that we can see and measure more accurately.
The first complexity is that your body doesn’t “burn” food in the same way that a bomb calorimeter measures the calories in food. The amount of energy produced when you burn food is not directly proportional to the amount of ATP produced when you digest as food.
Your digestive tract, combined with your Krebs cycle is very different from a furnace that literally burns food to generate heat. The number of calories in a food can only ever be an approximation of the energy that you will extract.
Food labelling also introduces a significant margin of error. The FDA allows food companies plus or minus 20% in food labelling. This is a substantial amount given you’re probably only targeting a 15% deficit.
Food manufacturers are allowed to round calories down, and when labels are based on serving sizes, rounding down an already small number can result in zeros showing on the label when this is not actually the case.
And then, how many people weigh out everything that they eat? Even if you weigh, do you occasionally sneak a bit of extra peanut butter when you lick the spoon or add milk in your coffee that doesn’t go on the scale?
It takes a LOT of time and effort to be precise with every morsel of food that goes in your mouth. Most people don’t successfully keep up the tracking over the long term (and many of the ones that do get a little neurotic about it). There seems to be something embedded deep within our psyche that rebels against our conscious efforts to override our natural appetite, urges and cravings.
We notoriously underreport our food intake. Even dieticians under-report by more than 200 calories per day, while the general population underreports by a massive 400 calories per day.
We always think we are a little better than we are (optimism bias). Our subconscious reptilian brain (that is ultimately in charge of keeping us alive) usually finds a way to get us to eat more than our conscious mind (neocortex) would like us to, especially if we are hungry after successfully dieting for a while.
Indeed we do have a hungry brain that is hard to tame (but is very good at keeping us alive)!
While the “calories in” side of the equation sounds complex, the “calories out” side of the equation is even messier!
This interactive version of the biochemical pathways in the human body will give you a taste of what is going on inside your body (note: all of these pathways depend on adequate micronutrients to function).
Most people estimate their calorie requirements using a theoretical formula (such as the Harris-Benedict equation) which is based on a lot of assumptions. They typically then apply a 15% deficit below this amount to set their target calories in weight loss. If you start eating to reach your new calorie target, there is a real chance that you will be eating more than you would have otherwise eaten because you are now chasing an arbitrary calorie target rather than eating based on your hunger cues to satiety.
Your total daily energy expenditure (TDEE) is made up of your basal metabolic rate (BMR), your thermic effect of food (TEF), your non-exercise activity thermogenesis (NEAT) and exercise (which is actually not a lot for most people).
- Both your BMR and your NEAT will reduce as you lose weight and your body adapts to conserve energy. You will stop producing as much heat, and you will stop fidgeting and other such involuntary activities that use up any excess energy from the extra helping of dessert you ate last night.
- Irrespective of the down-regulation of your metabolism, you will need less energy when you are smaller, so you will need to continuously update your target if you are going to continue to lose weight.
- Your TEF varies based on the macronutrient content of your food (i.e. protein generates more heat during processing, followed by carbs, then fat with the lowest TEF). This ‘metabolic advantage’ of protein is not taken into account in your calorie counts. Calories from protein, carbs, fat and fibre are usually treated as equivalent (which is a gross oversimplification).
We like to think we are super active, but the reality is that most of us are sedentary much of the time. We tell MyFitnessPal that we had a very hard workout. We then see the number of calories that our Fitbit or Strava tells us we burned and add that to our calorie allocation for the day or give ourselves permission to eat back those calories. It shouldn’t be too surprising that a 2016 study showed that the use of activity trackers made people less likely to lose weight!
So, the bottom line is that the “calories out” side of the equation is a moving target and constantly changing.
Tracking will keep you accountable
On the plus side, one benefit of tracking your food is that it makes you more mindful of what you eat and helps you to make better choices. If you have to track what you are eating, you will be a little bit more thoughtful before you eat it if you know you have to log it in Cronometer or take a photo of it.
Tracking your food enables you to keep a tally of what you ate. This can still be useful, regardless of whether or not you accurately weighed and measured everything that went in your mouth.
You are more likely to be mindful and think about what you are about to eat before it goes in your mouth. You may think twice before that second helping of your favourite indulgence if you are tracking your intake and already over your target for the day.
In any study, we get an Observer Effect where people change what they are doing because they know they are being watched. By tracking your food, you are harnessing the power of the observer effect.
Precision vs accuracy
The fact that food tracking is not accurate or reliable does not mean it is always useless. The image below helps explain the critical difference between accuracy and reliability. Our estimation of our food intake doesn’t necessarily have to be accurate to be useful.
Let’s consider the target in the top left corner (i.e. accurate and reliable). It’s unlikely that you’re going to be entirely accurate and reliable in your food tracking at the same time due to the inaccuracies related to food labelling. While this is what most people expect from their tracking, it, unfortunately, doesn’t occur in the real world.
Because of the various inaccuracies in food labelling mentioned above, we are unlikely to ever be accurate but unreliable (top right target).
A bodybuilder preparing for a contest who weighs and measures everything they eat and consumes a regimented diet will likely be inaccurate and reliable (bottom left corner). They will be eating similar things day to day, week to week with small modifications to make sure they keep moving forward. Even though their estimation of calories is not accurate, they are reliable, so their food tracking data is useful.
It’s worth mentioning that developing a regular eating routine with not too much variety is useful to maximise sensory-specific satiety. Constant novelty and variety will cause you to eat more and make it harder to be reliable or accurate.
If you don’t weigh and measure everything all the time you may be inaccurate and unreliable (bottom right target). While not as powerful, this data can still be useful.
Data Driven Fasting
For the many people who hate tracking their food, we have seen some amazing results with using blood sugar as a very actionable indicator of short term energy balance. Data-Driven Fasting helps people to understand whether they actually need to refuel or could wait a little longer to eat. That said, there are still benefits of food tracking, if done correctly, that we will cover in the rest of this article.
It’s a moving target!
To recap, food tracking is never accurate and often unreliable, and because your body continually adapts, the right calorie target for you at any time is a moving target! But the good news is this is not a problem that we cannot manage.
Unless your income depends on reaching an unnatural and unsustainable level of body fat, there is some value in listening to your appetite and cravings to ensure you are getting the nutrients (both macro and micro) that you need. Eventually, you probably want to eat “normally” again and maintain your progress without such a regimented approach that fights against your instincts. But in the meantime, you can use some modern tools to re-train your appetite and build new healthy habits around food.
Tracking your macros is invaluable to help you manage the satiety value of your diet. Left to our devices we tend to gravitate to the “autumnal” macronutrient profile (top left of the below diagram) that leads to weight gain. It can be useful to track your macros to ensure you are getting enough protein and staying away from the carb+fat danger zone. See Optimal macros for fat loss, maintenance and bulking for more details.
If you find your weight is not moving the way you would like it to, you can nudge your macros to move further away from the hyperpalatable low protein, moderate fat+carb zone. This will enable you to gain control of your appetite, with less reliance on the accuracy of your food tracking.
If you are weighing yourself regularly and tracking your food, you will know for sure that you can’t get away with that sneaky cookie or those extra leftovers in the fridge that look so yummy. Tracking your trend in body fat levels with a bioimpedance scale can be a useful way to ensure you are staying on track.
Tracking your food intake in Cronometer can also be invaluable to understand if you are obtaining all the micronutrients you need in your diet.
Focusing on the most nutrient-dense foods (per calorie) is a surefire way to help you control your appetite and maximise satiety.
As a general, rule nutrient-dense foods are more satiating and vice versa. It’s much harder to over-consume nutrient-dense foods, so you won’t need to focus on limiting calories as much. Check out the interactive version of this chart here if you want to drill down into the detail.
In the Nutritional Optimisation Masterclass, we see that when people focus on improving their nutrient density numerically, they tend to experience high levels of satiety and subsequent weight loss. It typically takes two or three weeks for people to re-train their eating habits by adding new foods and meals to improve their diet quality.
As they increase their nutrient density and give their body the nutrients they need, people tend to eat less without having to put so much effort into focusing on restriction.
Tracking is directionally accurate
While not precise, tracking your food intake is directionally accurate.
We are creatures of habit. Most people eat a similar quality and quantity of foods week in week out.
It may not be perfectly accurate or precise, but it is repeatable. You can use the information from your tracking to progressively modify your current habits and goals.
While tracking food quantity can be useful in the short term, focusing on food quality usually yields better long term outcomes.
If you know what you ate last week, you can make small adjustments for the coming week. For example:
- You can focus on hitting your protein target to help improve satiety.
- You can reduce your carbs to reduce your blood sugars if they are still higher than you’d like them to be.
- If you are not losing weight this week, you can try to eat a little less than you did last week.
- If you start losing too much lean mass vs fat you can increase your protein target.
This is not voodoo magic. It’s the science of continual improvement. You don’t need to be perfect, just a little bit better than you were yesterday.
Then, if you’re really serious about managing your weight or body composition and improving your diet, you can plan ahead rather than just responding to your appetite!
Rather than tracking what you just ate (How much did that weigh again? Dunno I’ll just make something up.), you can build your meal plan for the coming week in Cronometer to ensure you meet your macro and micronutrient targets.
If you find yourself snacking “off-plan” you can make your meals bigger or add in some healthy snacks for the following week and make sure you have them available when you are most often tempted.
If it doesn’t quite go to plan, you can update and then refine your plan for the following week.
When should you track your food?
While there are many benefits in terms of using tracking to re-train your food habits, there are downsides in terms of lack of accuracy, a false sense of security and losing touch with your healthy appetite signals.
While there are plenty of staunch advocates for strict tracking and a primary focus in CICO, there is also plenty of discussion in bodybuilding communities about intuitive, flexible and autoregulated eating and weaning yourself off tracking your food so you can listen to your hunger signals again while still reaching your body composition goals.
So when is tracking your food useful?
You may benefit from periods of tracking:
- To understand your diet quality (micronutrients),
- To help you dial in your macronutrients to manage satiety, body composition and blood sugars,
- If you have a lot of weight to lose and need to stay on track for an extended period,
- If you are trying to get down to very low levels of body fat, or
- Your progress stalls and you need to dial things back in.
When you do track, you can use a more relaxed tracking approach if your focus is food quality and are looking for a more sustainable outcome.
If you need results NOW, you may need to get serious about your tracking with weighing and measuring everything you put in your mouth, at least until you see the results you want.
Once you are getting results from tracking, you may be able to back off because you have learned new habits and routines. You know what foods you need to eat to achieve satiety and nutrient density.
You can think of food tracking as a crutch to help you until you are ready to make it work on your own. Let’s face it; most people probably don’t dream of tracking everything they eat for the rest of their life!
Once you are getting the results you want, you may want to take a break from tracking, if:
- You have built good eating habits,
- You are able to listen to your appetite signs for energy and different nutrients,
- Your blood sugars are dialled in, and
- You are maintaining the weight and body composition that you want.
Autoregulated eating habits should be the long term goal. But in the short term, some level of quantification can be beneficial to help you start your journey.
We have built the Nutrient Optimiser with all this in mind to help you build healthy habits.
Rather than just tracking your calories in vs calories out, the Nutrient Optimiser helps you fine-tune your diet quality at a micronutrient level with suggested foods and meals to help you obtain all your micronutrients.
With that in place, Smart Macros will also help you dial in your macronutrient targets based on your progress to fine-tune your targets to your body rather than some notional calorie formula.
- If your weight is not going down, Smart Macros will decrease your calorie target by 50 calories per day for the coming week
- If your blood glucose is still elevated, it will decrease your carb limit by 5 g. If your blood sugars are great, you can get on with focusing on more nutrient-dense high satiety foods and meals.
- If you are losing too much lean mass, we can increase your protein target to ensure your BMR doesn’t drop too much and you look muscular rather than just weak and skinny fat. Similarly, If you are not gaining muscle in a bulking phase, we can increase your protein target.
- Nutrient Optimiser also has a safety switch. When you log in each day, you report your hunger, cravings and energy levels. We also import your sleep and HRV data. This allows us to ensure that we don’t drive your calorie target into the ground when you’re obviously not coping. While this may slow your short term progress, it ensures long term sustainability and helps you avoid rebound binging.
The Nutrient Optimiser Smart Macros algorithm will use the information you give it and make recommendations about how to refine your intake going forward based on your weight loss, muscle loss and blood glucose.
In the end, it doesn’t matter if you’re not entirely accurate because the recommendations are based on your current logging. The Smart Macros will just adapt to your level of precision and accuracy to ensure you reach your goals!
Welcome to the brave new world of personalised nutrition!
Want to get started?
The best way to get started with Smart Macros is to use our Free 7-day Food Tracking Challenge. After a few days of tracking, you will get access to the Nutrient Optimiser which will guide you to make better food and meal choices as well as provide you with macro recommendations that will help you move towards your goal.