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A slow or damaged metabolism is a frequently discussed topic amongst people who struggle with body weight. This raises the question of whether this phenomenon actually exists and whether it is responsible for unwanted extra kilograms? Before you answer that it’s obvious, go back when you could eat everything you wanted up until the age of 25, you were in shape, and a few years later everything is suddenly much worse, so let’s together look in depth at the facts and myths surrounding metabolism. We will also share several ways to speed up the metabolism.
What is metabolism and how to understand it?
When it comes to metabolism, it’s often associated with trying to lose weight, gain muscle and the overall dimension of a healthy lifestyle. Rarely, however, is the concept sufficiently explained, and because of this it is riddled with a series of myths, half-truths and misleading information. What is this metabolism, anyway? Metabolism, or substance conversion, is a combination of biochemical processes that an organism uses to convert food into energy. Under this process, we can easily imagine all the processes that take place in the organism – from breathing to energy used by the cells and the end product of ridding the body of waste products, excretion.
But that is not what the vast majority of articles and conversations about metabolism have in mind. The term metabolism thus hides the rate at which our bodies convert food into energy, which they then use to cover all processes in the organism requiring energy. The rate at which we burn energy is simply referred to as metabolic rate.
Not rocket science, right? We eat and drink, then a lot of magic happens, and at the end of the process we can think, walk, play sports, build muscle and healthily thrive. The metabolic rate for our energy needs may be different from day to day, but the rate of basal metabolism remains virtually the same. And the faster our metabolism, the more energy (calories) we can burn.
What components does the metabolic rate consist of? Get acquainted with energy expenditure
- Basal metabolic rate (BMR) represents the energy required that our body needs to maintain vital functions such as breathing, heart activity and maintaining body temperature during sleep or deep rest. 
- Resting metabolic rate (RMR) is the energy required to maintain vital functions at rest without further activity. Resting metabolism accounts for approximately 60-75% of total daily energy output. [2-4]
- The thermic effect of food (TEF) represents the energy required for nutrient metabolism. The amount of this energy also varies from individual macronutrients. The TEF for carbohydrates averages 5-10% depending on their type, for proteins 20-30% and for fats 0-3% of their total energy content. Under rational healthy eating, the average TEF is around 10% of the total energy intake. [5-6]
- The thermal effect of exercise activity thermogenesis (EAT) is nothing more than the amount of energy consumed during intentional physical activity. EAT thus represents the energy we burn during a training session, match or competition.
- The thermic effect of normal daily activities (Non-exercise activity thermogenesis – NEAT) embodies the energy consumed for normal daily activities that are not intentionally performed as a sport. Therefore, we can imagine fine movements, such as leg tapping, change of body position, walking to work or housekeeping. [7-8]
No magic, detox programs or special herbs affect the rate of metabolism, or especially your overall lifestyle. The most impactful components of energy output are NEAT and EAT, which can contribute to about 20-50% to total energy output. 
Energy burnt through sporting activity generally varies depending on its type, intensity and duration. You will burn much more energy during a few hours of cycling or running compared to a quick home workout.
Energy consumed during normal daily activities, aka NEAT, is a huge difference in energy output. Let’s introduce two identical twins who live exactly the same life outside of work. One of the twins works behind a computer in an office as a clerk and the other as a construction worker. The difference in their total energy output will be huge precisely because of the difference in NEAT. And the energy intensity of a construction worker can be at least four times that of an office worker. 
Metabolic rate is predominantly determined by the size of the individual components of energy expenditure.
- Total daily energy expenditure (TDEE) = RMR + TEF + TEA + NEAT (TDEE = Total daily energy expenditure)
If you are interested in the subject of metabolism, read our article What Is Basal Metabolism and How to Calculate BMR? You can also calculate the basal metabolism value using an online BMR calculator.
What else affects the rate of metabolism?
- Unfortunately, or perhaps fortunately, age is equally inexorable to all of us, and the older we get, the slower the rate of our metabolism. This fact is linked to the gradual increase in body weight and the increasing candles on the birthday cake, but this is quite simplified. Ageing reduces muscle mass, but this can be effectively combated by strength training and an active lifestyle. 
- Gender is another factor influencing the rate of metabolism due to the different hormonal settings of the body, the different amount of muscle mass and the size of the body and internal organs of men and women. Again, although a little unfair, men are a little better off in this regard.
- Body size logically plays in favour of larger people. The larger you are, the more calories you need. 
- Muscle mass and body composition in favour of more muscle also requires more energy. What is the difference between a kilogram of muscle mass and adipose tissue? A kilogram of fat at rest per day consumes about 4 kcal and a kilogram of muscles about 13.5 kcal. [13–14]
- Genetics can be sneaky. Some people just aren’t lucky enough to win racehorse quick genes in the genetic lottery, but serious genetic defects that are directly linked to obesity play a role in less than 1% of the population. Without these genetic mutations, there is no specific gene variation that predisposes humans to overweight. 
- Hormones contribute enormously to metabolic rate, especially through the healthy function of the thyroid gland and the concentration of its hormones, which directly control the rate of metabolic events. Their deficiency (hypothyroidism) leads to a decrease in the rate of metabolic events and their excess (hyperthyroidism) leads to their acceleration. Both conditions should be compensated by optimal medical treatment. 
- The ambient temperature affects heat production, which costs the organism energy. In a cold environment, energy is needed a little more than in a warm environment. 
The rate of metabolism is influenced by a number of factors, some of which we and others are unable to influence. The positive news is that we can influence most of the components of energy output with an active lifestyle, thus tilting success to our side. There are other factors affecting energy output associated with hormone dynamics in the form of stress or sex hormones. Unfortunately, we are not able to grasp and define this issue precisely, but that does not change anything.
Despite the fact that everyone has a different metabolism, it is the individuality that needs to be recognized, learnt to work with, and not blamed on a slow or damaged metabolism. Life is just unfair, and the guy running next to you may have a slightly faster metabolism, burning more energy even if you look and live almost the same. No need to complain, but learn to work with your body.
Does a slowed and damaged metabolism prevent weight loss, and is it even possible to have a damaged metabolism?
1. My metabolism has slowed down or is damaged and I cannot lose weight
A common phenomenon associated with problematic weight loss is underestimation of energy intake and overestimation of energy output. In one study, a research group underestimated its energy intake by 1,000 kcal. The study participants in this group were convinced that their energy intake was less than 1,050 kcal, while the actual energy intake was roughly 2,080 kcal. This goes hand in hand with the discovery that this group overestimated its energy output by an average of around 250 kcal. Most people don’t have such a slow metabolism, they just underestimate their energy intake and overestimate their output, which prevents them from losing weight. [18-20]
You’ve been through a number of diets in the past, you eat very little, and you cannot lose weight?
Weight loss naturally occurs in the form of fatty tissue, but often also muscle tissue. The more weight we lose, the less energy we need, because we’re becoming a smaller version of ourselves. That’s not all. A slowed or damaged metabolism refers to the term adaptive thermogenesis. What is it, anyway? When losing weight, we also save energy in the form of reduced metabolism. It is not surprising, from an evolutionary point of view that we owe this mechanism as we are all still here today and that our ancestors didn’t die during long periods without food. [21-23]
Adaptive thermogenesis is responsible for a greater reduction in energy output than we could predict and calculate based on weight loss. Such a deviation can be about 10-15 % from the calculated assumption or about 50-500 kcal. You can see this as a set of changes by which the organism tries to keep us alive during periods of minimal energy, unfortunately this is also the case with weight loss. This is precisely the factor responsible for the ‘injustice’ that can cause a person who has never tried to lose weight and who is naturally slim to have a higher energy output of the 10-15% mentioned above, and thus to have an extra 50g of peanut butter, which is even more unfair. [21-24]
How long can such metabolic adaptation take? No one knows this yet, but the longest observed time is about 6 years after weight loss. This is also evidenced by the participants’ data from the popular American competition The Biggest Loser, where extreme weight loss occurs in a short time. But beware, this is also the “problem” of bodybuilding and fitness racers, who lose weight to a very low percentage of body fat several times a year to prepare for competition. [21-24]
But you can work with this, it is simply necessary to learn to eat according to your needs and live an active lifestyle. I know it’s easier said than done, but I believe you can do it all with our articles. If you want to get rid of a few extra kilograms and do not have a number of diets accompanied by a yo-yo effect under your belt, adaptive thermogenesis is not to be feared.
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2. With age, the metabolism slows down, so I cannot lose weight
It’s true that the average person’s metabolism slows down as they get older, but not in the way you might think. What causes the slowdown in metabolism? By decreasing muscle tissue and changing the concentration of sex hormones, especially in postmenopausal women due to the loss of oestrogen.  
But is this the whole story that can explain weight gain with age?
Lifestyle and exercise have the greatest influence on the rate of metabolism. Considering that a kilogram of muscle consumes about 13 kcal per day at rest, the famous slowdown in metabolism will not be dramatic from this perspective. The ideal tool against the loss of muscle mass is strength training and overall lifestyle habits. Remember how active you were at 20 and how active you are now. Is it not the slowing of the metabolism rather the reduction of total activity during the day and different eating habits?
3. I’m in “energy saving mode”, it keeps me from losing weight
Under saving mode, we can once again imagine the issue of adaptive thermogenesis, which we discussed in the first point. “Saving mode”, or slowing down the metabolism beyond the scope of body changes, can occur in people with a rich history of “dieting” and weight gain. But this makes the whole game itself “only” more difficult, not impossible. You need to learn to eat as per your individual needs, your lifestyle and metabolism to get the right diet with enough protein and associated sports activity.
4. I can’t lose weight because of genetics, I just have no control over it
Sure, someone might have a slightly better genetic makeup because their parents were in the right place at the right time in the past and met. Another may have slightly more “energy saving” genes, which in turn do not have a more pronounced effect on metabolic rate. As we have already said, serious genetic defects, which are directly linked to obesity, play a role in less than 1% of the population.  
Once again you need to raise your head, eat better and as per your needs, move and get as much sport as is naturally possible during the day.
5. Skinny people have a faster metabolism, therefore they are thinner
When we think about it, we find out it’s actually true. Unfortunately, not in such a way that we can blame the extra kilos on it. A faster metabolism of lean people means that they live a more active lifestyle and receive optimal amounts of energy. The difference in energy consumed during the day is huge between a person who has a sedentary job and doesn’t do much else, and a person who has a demanding manual job and actively partakes in sports. This could easily be a few thousand calories. This is mainly due to increased energy output through EAT and NEAT.
If you are wondering how much energy you should consume and how to calculate this intake, read our article How to Calculate Energy and Macronutrient Intake for Weight Loss or Muscle Gain?
How to speed up the metabolism?
- Eat enough calories. Optimal energy intake has a direct effect on the rate of metabolism. Once you drastically reduce your energy intake, the body feels threatened and starts to reduce the intensity of energy processes in the body and save energy. Weight loss should be slow and gradual in order to be sustainable in the long term. In the case of weight loss, set a calorie deficit of 15-20% and after some time of progress and achieving stagnation, adjust and reduce your energy intake again slightly. Stagnation (plateau) can occur in a matter of months, so do not panic and be dismayed after just a few weeks. Be patient and monitor progress correctly using body weight and body circuits.
- Pay attention to optimal protein intake. Proteins are the most nutrient rich, the metabolism of which consumes the greatest amount of energy. What happens if you eat 100 kcal of protein? On average, 20-30 calories are consumed by the body for protein metabolism, and you can actually use about 70-80 kcal. Optimal protein intake ideally in connection with strength training promotes muscle growth. Muscles burn more energy at rest compared to fat, but thanks mainly to them you will increase the amount of energy burned during the load. The ideal range for strength athletes due to muscle growth is 1.4-2.0 g of protein per kg of body weight. 
- Take up strength training. Thanks to strength training, you are able to compel your muscles to grow and strengthen. The best part is that about 24-48 hours after training, your resting metabolism is increased by about 5-10%, and you burn energy as if for free. The time and magnitude of acceleration of your metabolism depends mainly on the intensity and volume of training. 
- Don’t forget your endurance training. While endurance training does not have such an effect on the post training acceleration of the metabolism, you burn more calories during the same training time as compared to strength training. Running is one of the most energy-intensive sporting activities. An average 80-kilogram man burns roughly 660 kcal per hour of running at 8 km/h, and a 65-kilogram woman burns an average of 540 kcal. Now that’s worth going for a run three times a week, right?
- Move as much as possible during the day. Differences in normal daily activities that are not intentionally performed as a sport (NEAT) are one of the biggest differences in weight loss and acceleration of the metabolism. Instead of lifts, take stairs, take active breaks at work, walk whenever possible. Every move counts.
- Try HIIT. When faced with a lack of time, keep in reserve fast high-intensity workouts, where in a short time you put a decent amount into the body and burn a significant amount of calories. With HIIT, you can also see an acceleration of metabolism after training, which is not as great as with strength training.
- Get enough sleep every day. Sleep is vital for human health in all its aspects. When we are sleep-deprived, we have less energy, we don’t want to do anything, and concentration on work or study also lags. How does lack of sleep complicate weight loss? It increases appetite, plays with hunger and satiety hormones (leptin and ghrelin), increases levels of the stress hormone cortisol or decreases testosterone levels. I don’t have to go on, do I? Indulge in approximately 7-9 hours of quality sleep each day. [29-30]
- Drink water, coffee and tea. Adequate intake of fluids, ideally unsweetened water or mineral water is important for optimum operation of all biochemical processes. Unsweetened coffee and tea contain caffeine, which have thermogenic effects and can help with fat burning. However, do not exceed the maximum daily intake of caffeine, which according to the EFSA is 400 mg for the average adult. 
- Eat hot and spicy foods. The hot spices, for example, chilli peppers, contain capsaicin, an alkaloid responsible for the infernally hot taste of peppers and the acceleration of metabolism. Adding spicy spices to food can speed up your metabolism in the short term. 
- Use the power of stimulants and fat burners. Fat burners and pre-workout stimulants can speed up the metabolism by a few percent thanks to functional substances that often have a positive effect on concentration, attention and enthusiasm for training. Through this effect, you can increase the overall strength of these supplements.
If you are interested in more tips on speeding up the metabolism, read our article How to Speed Up the Metabolism and Burn More?
What is the conclusion?
The rate of metabolism in the form of energy output is a very complex issue. But the best part is that you have everything in your hands and the main components of energy output in the form of normal daily and sporting activities which can simply influence the speed of the metabolism. Using an active lifestyle with a well-designed strength training plan and diet developed to your needs, it is possible to speed up your metabolism and lose weight more effectively or maintain weight after losing weight.
Some may have a faster metabolism and others a little slower, but this is perfectly natural and there is nothing to do but learn to work better with your body and understand how your metabolism works specifically for you. It’s no big deal. All you have to do is try to eat better, given your needs, live actively, monitor progress and make any changes based on it. Work on yourself is possible, even if you feel you have been “cursed” by a slow metabolism or bad genetics. Nothing is as bad as it may seem.
Do you have experience with a slow metabolism? Share your advice and tips on speeding up the metabolism in the comments. If you liked the article, support us by sharing it so that your friends can learn about it.
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