Understanding Calories

A hot topic in recent times is around the widely used measurement of energy within foods, the calorie. You’ve probably heard of calories in vs calories out for weight changes, and the concept of ‘calories don’t count’, but I must admit this can certainly become confusing to most. This article will equip you with all the knowledge you will need around calories and their true role in the diet, giving you a better overall understanding to lead a healthier lifestyle.

‘We can see at this point why some may say calories in vs calories out doesn’t work. It’s not that the equation doesn’t work, but more so our inability to ensure the numbers add up correctly.’

Firstly, what even is a calorie? A calorie is the amount of energy required to raise the temperature of one litre of water, by one degree. We have been able to determine this number by burning food inside an enclosed capsule, surrounded by a small body of water at a known volume and temperature. We can then measure how much energy was used by looking at the temperature difference. Whilst this is great on paper and gives some form of context to the energy content within a food, our bodies are far more complex than a simple experimental design, and this is where the subject of ‘available energy’ comes into play.

Available energy, simply put, is the energy from foods that our body will be left with in the end, once all the digestive and absorption processes are complete. As an example, for every 100 calories of protein we consume, our body will only have 70 of those calories to use. The other 30 will have been used in the ‘breakdown’ process, hence why protein is considered more satiating than the other macronutrients: fats and carbohydrates.

On the other hand, most of the energy contained within a sugary product will be fully available to us. The nutrient quality must not be overlooked either, because a more complex starchy, or high fibre carbohydrate source will again provide us with slightly less energy, due to a longer breakdown process. In addition, more nutritious foods will of course help our bodies through numerous processes, ensuring we’re in good health.

If we solely look at numbers, we might not be getting the best diet we can, and we don’t want to restrict calories too low for the sake of losing weight at the detriment of our health. Over restrictions cause two main issues, which is the sustainability of dietary change, alongside the potential to cause nutrient deficiencies. Let’s say for example, you’ve gone onto a calorie tracking app, and it has given you 1000 calories a day to try and stick to. Your energy requirements in reality could be well above this, and whilst on one hand creating an energy deficit is important for weight loss, going too far in one direction means the likelihood of being able to stick to it is slim, and we then must also ensure the majority of those calories comes from nutrient rich foods, leaving very little, to no room for foods which are considered calorie dense, but enjoyable, such as crisps and cookies etc.

Another problem is the inaccuracy of numbers across the board, and I don’t just mean on the food label. It is well known that food labels are inaccurate when it comes to displaying calories, by as much as 30%, but in addition to this, we have self-reported data which can be out by a long shot if we’re not careful with measurements of portions, along with an inaccuracy of the apps calculations for calorie requirements in the first place. We can see at this point why some may say calories in vs calories out doesn’t work. It’s not that the equation doesn’t work, but more so our inability to ensure the numbers add up correctly.

‘It is clear that calorie dense, ultra-processed foods play a major role in hindering our abilities to manage our weight and health.’

But it doesn’t stop just there. We must then think about the food environment, our exposure to ultra processed foods and the current prices of such foods too. You could technically have an extremely ‘unhealthy’ diet, high in saturated fat, sugar, and salt, but still lose weight if your overall energy expenditure is higher than your energy intake, and in todays society, this seems to be the easier route to take too. Convenience foods can be far cheaper than what we would consider to be healthier options, and our exposure is through the roof too. We have advertisements, emails and text messages with offers, visual cues on social media platforms to name a few, and this seems to make eating a healthy balanced diet all the more challenging.

Ultra-processed foods have been stripped from fibre and protein, which are both beneficial in creating the sensation of fullness, whilst also reducing the overall available energy. When ultra-processed foods are void of these components, the flavour is then usually replaced with salt, sugar, or fat. The problem here is then our ability to stick to a recommended portion/serving size, because of the great flavours within, and this can lead to a much higher energy intake overall.

Our bodies response to whole foods vs ultra-processed foods is completely different, irrespective of caloric content. Lets say I gave you 300 calories of ‘treats’ and then the same caloric value of whole foods. Which would you likely want more of given the choice? We may also feel less fulfilled from the ‘treats’ as the volume of food will be far smaller too, which has the potential to leave us still feeling hungry afterwards, and with a strong signal from the body to say ‘I’m still hungry’, we would probably help ourselves to more.

So, what is the solution? It is clear that calorie dense, ultra-processed foods play a major role in hindering our abilities to manage our weight and health and should be replaced with whole foods that are naturally higher in nutrients, protein and fibre. Calorie tracking apps certainly have their place if the individual finds it helpful, but it is worth being mindful of common inaccuracies present on the app and/or food label, whilst not forgetting about the quality of the food too. If going down the route of tracking numbers isn’t for you, then similarly you would benefit from reducing the ultra-processed foods, increasing the amount of nutrient dense foods from a mixture of food groups including fruits and vegetables, starchy carbohydrates, meat and plant-based proteins, dairy and oils and spreads. Relying less on convenience foods and opting for more frequent home cooked meals will help with the process, and this can all be done in conjunction with an increase in physical activity to maximise positive health outcomes down the line.

Wrote by Eugene Gristock, BSc, ANutr

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