It is very helpful to know how our body works. Even though we can’t live in blissful ignorance any longer, we can actually use that information to our advantage. Just to be sure you won’t be disappointed in the middle of the article, today I will talk about the general description of how our metabolism works. You won’t find here and magical formula on how many calories you should eat to lose weight or how many calories you burn while walking. These things are so individual, that it would be impossible to find them on the internet. But the things written in this article might actually help you to figure these answers out on your own.
What is a calorie?
Before I jump into the main topic of the article, I think it is very good to know, what is a calorie since I will throw this word here and there throughout the whole text. A calorie is a unit of measurement. One calorie is the amount of heat that is needed for one gram of water to raise its temperature by one-degree Celsius. It is also an energy that is received and burned by our body. With time, we learned to say only the term “calorie” when talking about our bodies (for example that our lunch has 500 calories) but in reality, we mean kilocalories (that is 1000 calories) – kcal.
Energy output (expenditure)
As I already said, our body uses calories to produce energy. But how exactly it is produced? Our total energy expenditure is based on four components: basal metabolic rate, non-exercise activity, physical activity and thermic effect of food.
Basal metabolic rate
Basal metabolic rate is an energy that is needed for our body to function. What I mean by that is maintaining body temperature, keeping our organs going (repairing them, helping the cardiovascular function of the heart), maintaining ionic exchanges between cells, and respiration. It is an energy that you would burn even in a scenario when you would just lay in your bed all day and do nothing (no eating, no drinking, no walking, etc.).
It is about 60% of the total energy expenditure for an average person (by that I mean a person who is not burning thousands of calories during sports etc.). The basal metabolic rate is very individual – it can be totally different even for two people of the same height and weight. It depends on the height, weight, age, sex, fat percentage, amount of muscle but also it is influenced by genetics.
It is quite self-explanatory but it is an energy that is burned during an activity that is not an exercise. It is an energy that you need to function every day – walking from room to room, studying, sitting, cooking, showering, walking up the stairs, standing, etc. It can make a big difference in a long-term period. It is basically our lifestyle – if someone has a sedentary job and when they come home they just watch the TV, they will burn much less than for example a waitress who walks 8 hours a day and when she comes home she cooks and cleans the house.
This is energy burned during a workout. It can be anything from walking, running, dancing to lifting weights or playing tennis. In some sources, it is in the same category as non-exercise activity and then any movement of the body (opposed to laying down) is a physical activity. For me it makes more sense to divide those two as many people imagine running, lifting weights, or some kind of manual work when talking about physical activity.
Thermic effect of food
The last component is the thermic effect of food. That is an energy that the body burns during the digestion of food. It is logical that the more we eat, the more our body has to work to actually process the food but we can find a difference in the amount of burned energy between different components of food too! Some macronutrients are more energy demanding than others. Protein is the most energy-demanding, carbohydrates are second, and the least demanding is fat. That is one of the reasons why protein is important even in a calorie deficit – it takes longer to digest (which means it will fill you up for a longer time) and the digestion will burn more calories.
Another factor in the number of burnt calories during digestion is whether the food is processed or not. Unprocessed food (or in other words- whole foods such as fruit, vegetables, legumes, etc.) is going to burn more calories than processed one. You can take it like that- when food is being processed in the industrial process, it is being “pre-digested” for you, so your body won’t have as much work with it later.
How to know what is our energy expenditure?
When we take into consideration those four components, how to actually know how many calories we burn in a day? Well, there are countless calculators and equations on the internet which will count it for you, but those will NEVER be accurate. No equation or calculator can calculate how your individual body works. But then what?
The best way how to know how much your body needs in a day is through your own research. If you are maintaining your weight for some time, all you need to do is to measure your food and log it into an app (for example “myfitnesspal”) for a few days (the more days you will do it, the more accurate it will be). The average of those few days will be your maintaining calories and from that, you can know your own calorie deficit or surplus. In the case where you are slowly gaining weight week by week, you can follow the same process only in that case the calculated calories will be most probably a slight surplus for you. You can just deduct for example 10% of those calories and try to follow that. If you maintain your weight on that number, those are your maintaining calories and you can go from there.
It is a journey of try and error but it is also the only way how to find your unique energy expenditure accurately. Because if you do it this way and you find out that your maintaining calories are 2300kcal, it can be so different from an internet calculator which would give you for example 1700kcal to maintain your weight and 1300 to lose weight. So instead of a calorie deficit of 1800kcal, you would be eating 1300kcal and that would be serious under-eating which could lead to more problems down the line.
Here it is quite easy. Energy input is everything that we eat or drink (if it is not water which does not have any calories). Each food has, of course, different caloric value and therefore it depends on how we build our diet in general. Some people are able to eat intuitively the amount of food that their body needs and they just strive to maintain their weight. In that case, they don’t need to know how many calories each food has. But if you are unhappy with your diet and your health, it is a good start to get to slowly know the food you are putting into your body because it very much influences the quality of your life.
Losing weight, gaining weight and maintaining
Here we will briefly discuss how to use the information above on a way to our goals.
While losing weight, you have to be in a calorie deficit which means you will have to have bigger energy output than input. There is no other way to lose fat than through calorie deficit even though some weight loss products will tell you otherwise. Yes, there is this argument which some people use: “I started to eat more and I lost weight,”. Is it true? Yes and no. They could lose weight because they simply started to eat more and therefore stopped occasionally binging or snack so in a greater scheme they consumed fewer calories than they did before. Or they simply just ate more than they thought before. The other reason for that could be that with eating more, their energy expenditure increased as well so even though they ate more, they still managed to create a calorie deficit and therefore lose weight.
If you rapidly decrease your calories, your basal metabolic rate will decrease immensely with time as well (there is a smaller thermic effect of food due to less food in a system and also the less you weigh, the less energy your body needs to maintain it). Not only that, but your non-exercise activity and physical activity will burn fewer calories as well. If we are tired, we are most likely to use an elevator instead of walking up the stairs or just lean onto a wall when we are standing instead of supporting our body by ourselves.
With that, during our workout, we are not able to give as much effort as we can when we are eating more. Those are more subconscious and you won’t probably even notice it if you don’t pay close attention to them. Because of that, it is important to have an appropriate calorie deficit to our normal energy expenditure and not to lean to severe restrictions.
With long-term severe restriction, there come ravenous hunger and immense exhaustion. Our body then tries to save calories where it is able to and it not only slows down movements but also turns off “unnecessary” functions for survival – for women is it for example menstruation. In that case, it is very important to increase the number of calories – for example through “reverse dieting”.
The last thing I would like to add to this topic is a concern about “damaged metabolism”. A lot of people say they eat so little but still can’t lose weight or even that they can’t lose weight BECAUSE they eat so little and it is because their metabolism is damaged. That is not the case. If our body is in a calorie deficit, it will always lose weight. That’s just how it works.
Usually, a person who is overweight most probably has a much higher basal metabolic rate than a person of the same height but with a “healthy” weight (because the more person weighs, the more energy their burn just to keep the body going). The area of possible mistake is that the non-exercise activity and physical activity is almost non-existent. In that case, the body burns its calories only through basal metabolic rate and thermic effect of food, but that won’t get us very far and the individual won’t burn as many calories throughout the day.
In contrast to that, in those cases, it is very very easy to eat more than we burn, especially if we forget half the things we have eaten. It is very simple to remember our breakfast, lunch, and dinner. But what about the handful of chips, or a teaspoon of peanut butter during cooking, or those nuts we have eaten in the evening with a glass of wine (and we don’t think about that wine either)… It is sad but those things will add up way too quickly if we don’t do them consciously. In those cases, it is very important, to be honest with yourself. Because it would be impossible not to lose weight if your body is in a calorie deficit – maybe it would be possible if the laws of thermodynamics didn’t apply to you, but you would most probably be dead in that case.
So, the term “damaged metabolism” is being used when people are not burning many calories during the day and eat more than they burn even if they don’t realize that. What to do in that case? We can make a major difference with small steps- a 30-minute walk every day, standing on a tram, walking up the stairs instead of using the elevator, stretching while watching TV, dancing during cooking, etc. As much as little nibbles of food here and there add up, those little activities add up with time as well and it can make a big difference in the long term.
Maintaining and gaining weight
Just shortly to that topic. We are able to maintain our weight if we burn approximately the same amount of energy as we eat and we gain weight if we are getting more calories than we are able to burn in a long term. However, if we gain a muscle mass, our basal metabolic rate will increase as well, because muscles are very energy demanding and with time we can build a body that will be able to effectively use a big amount of calories.
Take your time
To figure out, how many calories our body burns or how many calories we are actually eating is not easy and it takes time. It can take us weeks and months to figure it out. What I would say is not to rush it. Some people have lost so much time trying to lose weight and then gained it all back, jumped from one diet to another, and calculated their calories on the internet a million times over and in the end, they are right where they started. Isn’t it therefore more logical to just take the time in the beginning, collect information and data about our body which then can be used in the future?
If you will focus on that first and later provide your body with good quality food which will help you on your way to a healthy lifestyle, there is no reason for your results not to come. I hope this article has given you at least one new piece of information and I will be looking forward to seeing you in the next one.