One of the most important articles you can read to gain the fundamental knowledge to understand how your body works.

As boring as it is, I want to start this series of articles with some definitions so that we know what we're talking about, what's useful where and what's what, man, in simple, straightforward Greek.


Nutrients are divided into two types: Micronutrients and macronutrients.

Two types of so-called micronutrients are known to everyone. Vitamins and minerals. These ingredients are needed in very small amounts by the body, but they are essential for the proper functioning of the body.

However, micronutrients do not provide us with energy (calories in short).

Unlike micronutrients, macronutrients are substances that we get from our diet, but which provide us with energy. These are the following three:

  • Carbohydrates: One gram of carbohydrate equals about 4 calories.
  • Proteins: One gram of protein equals about 4 calories.
  • Dietary fat: One gram of dietary fat equals about 9 calories.

There are other nutrients, which, depending on the literature, can either be attributed as macronutrients, or not mentioned at all, or considered separately:

  • Alcohol: One gram of alcohol equals about 7 calories. Many times the literature either omits it or states that it provides energy, but notes that it is not a macronutrient as it is not needed by the body.
  • Water: Water is used as a carrier of micronutrients and macronutrients and its role is essential in the process of distribution and absorption by the body. As with alcohol, it is often omitted in the literature as it does not provide us with energy.
  • Phytomolecules or phytochemicals: Technically not nutrients. They are chemicals that are produced by plants and research shows that they have health benefits. The only reason I am listing them is that a lot of scientific research has been started on them and it looks like they will be of interest in the future.


Hormones are chemicals secreted by the glands, which when they reach specific cells, they receive a signal to start a process.

This process is targeted and only the cells that need to receive the specific signal will receive it. If you remember the example I gave in "Local Fat Loss": you can imagine the receptors in our body cells as puzzle pieces. Only the right type of molecule can apply to the right type of receptor, so the cell receives the signal to do something.

Hormones. Messengers of the glands that carry orders to the cells.


Metabolism is a word that is used so often, but most people don't know exactly what it is.

When we refer to metabolism, we mean a series of physical and chemical processes that take place within the cells of the body. The conversion of carbohydrates, proteins and dietary fats into energy is part of the metabolic process and the main form of energy for cell metabolism is ATP (adenosine triphosphate). We will meet ATP again in the future.

Metabolism is divided into two parts: anabolism (creating something) and catabolism (destroying something). In short, when a bodybuilder uses steroidal anabolic agents, he does so in order to artificially create anabolism in the muscles.

If we were to use the word in everyday life, we would say that the metabolism of the furniture factory stumps trees to stump tables. And yes, I know I don't have much of an imagination.

Let us note that metabolism depends on the thyroid gland, through the hormones it secretes. These are mainly T3 and T4 (thyroxine and triiodothyronine for those who like technical terms, but this is not school, there is no way I expect anyone to remember these names and I will not use them in the future). There is a third hormone, calcitonin, which is responsible for calcium metabolism.

Finally, always keep in mind the following: metabolism is not interested in the concept of time. It wants to metabolize things NOW in order to provide things that the body needs NOW. It will do its job regardless of what you are doing and what time it is. And he certainly doesn't care about the future as he can't borrow to pay for it.

Metabolism. The breaking down or synthesis of any part of the organism into something else so that it can be used by the organism.  


Oh. Here we ran into a bit of trouble, at least in terms of trying to explain it in plain Greek and not science fiction. It's not going to hell, let me give it a try.

There are more than 300 amino acids. 22 of these have the ability to make proteins, while the number of amino acids that can make protein in the human body is 20. Proteins are created when amino acids are joined together several times, eventually forming a sufficiently long chain (proteins are very large molecules, which is why they are called macromolecules). And since the second most important component of our muscles after water is protein, we begin to understand their importance.

But the importance of amino acids does not stop there. Our cells are largely made up of amino acids, which are responsible for many important functions. They also help in the distribution and storage of nutrients by the body, as well as in the removal of metabolic waste from the body.

And there's a lot more that they offer to the human body, but I think you get the point. They're important.

Finally, I have to deal with a technical term because it will be of concern in the future. You remember that amino acids join together many times to form chains, right? Well, the first formation that two amino acids make when they join together is called a peptide.

Amino acids. One of the most important building blocks of living organisms, which are broken down into proteins.


Here we have fallen into easy ones, strange as it may sound.

Enzymes are large molecules (like proteins, they are macromolecules) that speed up metabolic processes. The rate of acceleration they provide is several million times faster.

The table contrasts the time of metabolic processes without enzymes (third column) and with enzymes (fourth column). Source. Biochemistry. 8th ed. New York, NY: W.H. Freeman, 2015, p. 216.

So you understand that without enzymes, it is doubtful that life could exist.

Enzymes. Powerful biological catalysts.


What is homeostasis? A fancy word used to describe something simple: the consequences of the human body being built to adapt under any conditions.

Technically speaking, it is the maintenance of a stable internal environment within an organisation.

If you are on a particular diet for a long time and for any purpose, the body will become more efficient at breaking down these ingredients and the initial benefits of it will diminish over time.

If you are in a caloric deficit for too long, the thyroid will send a signal that your metabolism is lowered and you need to consume fewer calories during the day.

The longer an exercise is part of a programme, the more the diminishing returns will be felt.

The second dose an addict takes does not feel the same as the first. Even worse is the third.

Does the coffee you drink in the morning have the same effect on your body as it did when you first started? You can thank homeostasis for that.

In any homeostasis situation, there are 3 systems that communicate to bring it about:

  • The receptor or sensor: detects the change.
  • A control centre: is responsible for controlling the reaction to change.
  • The operand: completes the commands given by the control centre.

There will always be a delay from the moment the event took place until the start of the process of co-existence.

And always, always, when we talk about homeostasis we should think of the control centre as a thermostat and not as a knob or a switch or anything else.

Imagine a freezer that is set to maintain a certain temperature. When the temperature sensor detects that it has dropped, it will send a signal to the freezer board to reduce the cooling system's output. When the sensor detects that the temperature has risen, it will send a signal to the freezer board to make the cooling system work harder until the temperature drops to a certain level.

Temperature sensor -> Receptor.
Board -> Control Centre.
Refrigerant Gas-> Operator.

Homeostasis. Whatever you do, your body will adapt to it.


And we come to the heavyweight champion. If you thought concepts we've seen so far like metabolism and homeostasis were incredibly interesting and important in terms of the implications of how and why your body reacts the way it does when it should, prepare to have your mouth left open.

I won't lie, this is probably the most difficult concept to describe in simple terms although there are many technical things I will deal with in this blog.

So let me go ahead and say it as bluntly as I can: Homeostasis is a naive model. Why?

Remember the examples of homeostasis I gave. The second dose of heroin will not feel the same as the first, even worse the tenth. The body has adapted. Is this good? Do we agree? But if it's that simple, then why are there heroin addicts? Why does a person become addicted if the body adapts to these substances? If the body has adapted, why is there an addiction to these substances?

Homeostasis, as we are beginning to understand, has significant gaps in the explanation of how the human body works. Homeostasis is therefore a naive model of why:

  1. It assumes that there is a certain normal level for everything in the body, and when these levels are disturbed, homeostasis kicks in to bring them back to the previous levels.
    But that is not the case. The reality is that any such levels vary according to circumstances. Our blood pressure levels are different when we exercise and different when we sleep.
  2. It assumes that this normal level is controlled by a local regulatory mechanism.
    But that is not the case. The reality is that our brain coordinates changes throughout the body and often this includes changes in behaviour.

And that's how we get to the alienation. This was originally intended as a theory to replace homeostasis, but it is now considered part of homeostasis, although as concepts they have tremendous differences. Continuing and summarizing the differences:

  1. Allostasis considers that normal levels are different under ideal conditions and different under stressful conditions.
  2. Allostasis accepts that disturbed levels can be adjusted in an incredible number of ways and that each of these has its own effects.

Allostasis is essentially telling us that our organism will always seek stability through change. An incredibly important concept. And even more important? The organization will change or continue to change regardless of whether that change continues. The organization will seek to seek stability through change, even as it anticipates a future event that will disrupt it.

So, the second and third doses may make less of an impression, but the allostasis has already taken effect and is trying to find a way to change everything in you to bring stability to your body. And so, as a result, you become a heroin addict.

Allostasis. When there are or are expected changes in the organization for which external factors are responsible, the organization will change so that it can remain stable as a whole. Stability through change.


Look again at the example of alienation that I bring. Heroin. Hardly one of the things one would say is a stressor, yes?

So let me give you another example. Cocaine, normally speaking, has no reason to be addictive. And yet, to stop the user is incredibly difficult. So is marijuana.

Unless you live in triple-triple country and have contact, you will know that like cocaine, there is no physiological reason for marijuana to be addictive. But it's not easy to stop.

I hope we agree up to this point.

So we have a clear picture of what stress is on the part of our body.

We can say it like this: When there is an external factor that brings about a change in what the body considers to be a normal level, then from the point of view of our organism this is stress or strain.

This external factor, the one responsible for the stress, is called the stressor.

  • Stress is a stressor.
  • Work is a stressor.
  • Gymnastics is an overworker.
  • The caloric deficit is an ingester.

Coach. Any external factor that brings about a change in the physiological levels of any part of the body.

Stress. Any change in the normal levels of any part of the body by a stressor.


Okay, I know when I'm being tiresome. Some may find what I've said so far useless or difficult or boring, but believe me. If I didn't think they were important I wouldn't have mentioned them.

I know that the average person does not like fancy terms and complex concepts. I know that such articles can drive people away from this blog and waste my efforts, no matter how easy to make them.

However, such articles are like mathematics. When we did them in school, we were all told that they were useless and that we wouldn't use them in our lives. And yet, we use them every day.

I promise that from the next article which will deal with how the body works, I will get to the heart of the matter. That is, I will talk about factors that relate to fat loss and fat gain.

After all, strictly speaking, even eating food per se is an ingestor, isn't it?

Until next week!

Next: How our body works I  >
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Caballero, B et al. Encyclopedia Of Sciences And Nutrition. 2nd ed. Amsterdam, Netherlands: Elsevier Science B.V., 2003.

Shier D, Butler J, Lewis R. Hole's Essentials Of Human Anatomy & Physiology. 11th ed. New York, NY: McGraw-Hill, 2011. gropper SS, Smith JL. Advanced nutrition and human metabolism. Belmont, CA: Wadsworth, Cengage Learning, 2013.

Listrat A, Lebret B, Louveau I, et al, "How Muscle Structure and Composition Influence Meat and Flesh Quality." The Scientific World Journal, vol. 2016, Article ID 3182746, 14 pages, 2016. doi:10.1155/2016/3182746

Berg JM, Tymoczko JL, Gatto GJ Jr, Stryer L. Biochemistry. 8th ed. New York, NY: W.H. Freeman, 2015.

Sapolsky, RM, Why Zebras Don't Get Ulcers. 3rd ed. New York, NY: W.H. Freeman, 2004.

McEwen BS, Wingfield JC, "The concept of allostasis in biology and biomedicine", Hormones and Behavior, Volume 43, Issue 1, 2003, Pages 2-15, ISSN 0018-506X, (

Sterling P, "Allostasis: a model of predictive regulation", Physiol Behav (2011), doi:10.1016/j.physbeh.2011.06.004

Sterling, P., & Eyer, J. (1988). "Allostasis: a new paradigm to explain arousal pathology", In S. Fisher, & J. reason (Eds.), Handbook of life stress, cognition and health (pp. 631-651). John Wiley and Sons Ltd.

-Suprastratum: The authority on health, fitness and nutrition

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Author: Nick Krontiris

Founder, Suprastratum



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