PROTEIN, CARBS, FATS, SATIETY, AND THE ENERGY SYSTEM!

PROTEIN

*As always, please find all sources cited at the bottom of the article!*

Pro.G.I. cares deeply about the natural ingredients we use, with none being more important than PROTEIN! It’s so ingrained into Pro.G.I. that we saw no other option other than to make it half of our name! It makes a heap of sense, then, to have a deep-dive into what exactly protein is - throw away all of the stigmyth (I’m coining that stigma-myth combo) - and get right down to the bare essentials of the macronutrient that is Protein.

TDLR

Proteins, comprised of amino acids, are the building blocks of life, influencing everything from body tissues to hormones. Skeletal muscle, the major protein-demanding body tissue, and the Sliding Filament Theory are explained. Protein's impact on physiology is immense, aiding in birth weights, muscle maintenance, and especially getting JACKED. The endocrine system, fueled by proteins, controls hormones like Ghrelin, affecting appetite and more. In the energy system, Adenosine Triphosphate (ATP) is the key, with protein having it’s own ATP generating pathway. Alimentology explores protein completeness and satiety, revealing protein's role in satisfying hunger and promoting fullness. Pro.G.I. advocates for increasing protein intake, understanding amino acid profiles, and focusing on dietary inputs for lasting health improvements.

TEH SCIENCE!

Biology (1,7)

What actually are Proteins? Proteins are, fundamentally, folded amino acid (AA) chains. AAs are a nitrogen-based molecule that acts as a building block for proteins and peptides. AAs chain together based on the acidity of their environment, and are then folded about themselves within a particular cell structure, the ribosome. These ribosomes facilitate the Ribonucleic Acid-Amino Acid interaction, which brings about a protein (1,7). There are 20 different AAs currently identified, with 12 being non-essential and 8 considered essential (In children it’s slightly different: 11 non-essential, 9 essential). All that separates an essential AA from it’s non-essential counterpart is whether it can be synthesized in the body. Essential AAs cannot be created within our bodies from other AAs and as such must be acquired from food (1,7). This is also what determines the “completeness” of a protein source. If you’ve ever come across the term “incomplete source of protein”, this is why - That particular source doesn’t contain all 8 essential amino acids, hence it cannot be a person’s only source of protein (1,7)

Why is that important? I dunno - but that’s teh science.

On to the good bit - what are proteins actually good for?

Proteins do SO many amazing things - pretty much anything that actively does something in the body is a protein, or is a result of a protein’s work. Enzymes? Proteins. Endocrine (Hormone) system? Proteins. And muscle? You guessed it. STEROIDS. Jokes! (although only kinda?) That’s protein again.

Now, I’m oversimplifying it - but if a little cartoon youtube history channel has taught me anything, a little bit of “oversimplified” can be a very good thing! The main concept to get is that on a biological level, proteins are essential to life, but further than that, they also affect our physiology.

Physiology (2 - 8)

It’s fairly hard to overstate the level of the effect that proteins have on our physiology. Proteins can be used by the human body in 2 major ways:

As building blocks for body tissue (muscle, organs, connective tissue) (2, 3, 5)
Is involved in the endocrine system (used to create hormones, enzymes, etc.) (6, 7, 8).

From contributing to a normal average birth weights in babies, to helping the elderly maintain lean body mass (muscle), to helping the lads get JACKED (There has indeed been a HEAP of research on this), the evidence for the impact of adequate protein intake is becoming insurmountable (2, 3, 5, 6, 7, 8). If we want to be equipped to be Pro(G.I. - ha), aim for gold, and reach the pinnacle of what our bodies can be, we need to start by understanding the physiological uses of protein, which itself begins with our body’s structural building blocks - proteins.

The Building (2, 3, 5)

It’s pretty amazing to see, but the list of body tissues whose function relies on protein is extensive. Connective tissues (Tendons, ligaments, fibrous sheaths, cartilage), Epithelial tissues (skin), Nervous tissue (White and Grey matter), Blood Tissue (Haemoglobin) and Cardiac system (Smooth muscle), Bone (Collagen Framework), and Lipoproteins in Adipose tissue (Cholesterol / Fat) is FAR from an exhaustive list (3,5). And yet one tissue reigns as king over all when it comes to protein; perhaps the most obvious and most relevant to most people - Skeletal MUSCLE.

That’s right, the big kahuna when it comes to protein. I mean, who wouldn’t want to look like a pile of shiny circles stacked on top of one another like some strange Connect Four amalgamation?! Although, it is important to remember that maintaining lean body mass (bone AND muscle) can be not just important for self-confidence and mental health, but literally lifesaving in populations like the elderly (2,3). For us to comprehend the impact of muscle, we first need to know what it actually is, and how it operates. Enter: the Sliding Filament Theory.

Sliding Filament Theory (11)

The theory first proposed in 1954 by Andrew Huxley, plus the proceeding 50+ years of further research have produced a mountain of evidence to support that this is indeed how the muscle works on a foundational level.

Simply put, the way it works is like this:

There are 2 (recently indicated to actually be three) major protein structures involved - Actin and Myosin.
Through the action of the Cross-bridge Cycle, small nodules on Myosin, called myosin heads, attach to the actin filament and PULL (called a power stroke). This slides the filaments past one another.
With the application of Adenosine Triphosphate (ATP - I’ll outline ATP a little further on!), the myosin head detaches from actin and gets cocked back into a ready position (like cocking a gun), ready to reattach to another part of the actin filament

The sneaky 3rd filament that has just come to the fore within the relevant sciences is called Titin, and has been suggested to accomplish a number of things - mainly when it comes to activities such as jumping (Plyometrics).

Where Protein fits in is that higher levels of protein intake are very closely linked to having more parallel sarcomeres (the most basic complete unit within a muscle cell), making the muscle bigger and stronger. It really does make perfect sense. If muscle is fundamentally made up of sarcomeres, and the two (three!) main elements of a sarcomere are two types of proteins, then more protein = more muscle. Whoever said that meatheads don’t need no math?

The Endocrine System (6, 7, 9, 10)

The second part to the significance of protein lies in the Endocrine (Hormone) system. Hormones are everywhere in the body. To put it very basically, it’s really just a super complex and intricate messenger system that tells different parts of the body to function in a particular way at a particular time (6).

Perhaps an example could be helpful here: Ever gotten the munchies? Been desperate for maccas after you haven’t eaten for a couple hours? That feeling comes (in large part) from a hormone called Ghrelin. Ghrelin has been shown to increase before a meal and sharply decrease following eating your fill. As your stomach digests food (called Gastric Emptying), less pressure gets put on the lining of the stomach. Your stomach responds to this decreased pressure by releasing Ghrelin, which enters the blood, gets to the brain, and tells you to “EAT STUFF. NOW.” (9, 10). Where protein comes in here is that Ghrelin itself is composed of 28 amino acids, the building blocks of proteins.

Ghrelin has such an extensive effect on the body in relation to appetite, taste sensitivity, Growth Hormone and a ton of others that it is absolutely worth checking out the Ghrelin article from Müller and colleagues (9), and copy-pasting the introduction and conclusion into ChatGPT to get a summary. The main thing to know is that the Hormone system is always on, operates in ways that you don’t even notice, is completely crucial to you actually being alive, and is dependant upon proteins (amino acids) to create many of the relevant hormones.

The Energy System (4, 7, 10)

Last (for now!) of the main components of protein’s importance resides in the Energy system. There is one way, and one way only that your body gets the energy it needs to operate - Adenosine Triphosphate (ATP) (4). There are four components of ATP - the Adenosine molecule, and three Phosphate molecules, hence Adenosine TRIphosphate (The dudes/gals who figured this out were amazing scientists, but not particularly creative with the whole ‘naming stuff’ thing). The energy your body uses to do everything it does is carried by ATP. The way this energy is accessed is by using enzymes to chunk off one of the P’s from the ATP molecule (“chunk off” is the official scientific terminology) (4). This converts the ATP into ADP (Adenosine Diphosphate), with “Di” meaning “two”, plus a free Phosphate molecule. This can be done with ADP to form AMP (the M standing for “mono” or “one”). Breaking of the bond between the last two phosphate molecules releases a puff of energy that our bodies can then use for various activities (4). This is how we get ALL of our energy - popping off Phosphate molecules from ATP or ADP. Not some. Not even most. ALL the energy. That means the only way for us to keep getting energy, is to continue to generate ATP.

There is a beautiful buzzword for ATP generation: Metabolism. In general, for our bodies to generate ATP we need to break down (metabolise) any of the “holy trinity” of macronutrients - Carbohydrates, Fats (Lipids) and Proteins (4). To be a little reductive (kinda like this entire article!), for each of these there is a method to create ATP: Glycolysis for carbohydrates, Beta-Oxidation for fats, and Deamination for proteins (4). The important thing to take in here is that there are different methods of metabolising each macronutrient - with some methods doing multiple macronutrients, and all methods occurring all the time at different rates - and that protein produces less than half the amount of energy as carbs and fats. This is because deamination only produces ATP indirectly, making the process rather inefficient (4, 7, 10). This is part of the reason why getting more protein in your diet can be a really good thing! Since protein is not calorically dense, eating more protein can be a great way to reduce your total caloric input for a day.

Yet there is still one aspect to dietary protein that is even more crucial - and it’s all about the science of nutrition and diet: Alimentology!

Alimentology (Nutrition) (1, 2, 7, 10)

Pro.G.I. rests entirely on the foundation of two key sciences - Physiology, into which we’ve already looked, and Alimentology (nutrition). To delve into the nutrition of dietary protein, there are a couple of concepts to tackle. The first is “completeness” of a protein, while the second is “satiety”. (2, 7, 10)

Complete vs Incomplete Proteins

Whether a protein source is considered complete is dependent on it’s Amino Acid profile. As mentioned earlier, there are 20 types of amino acids, each with a variety of chemical make-ups; Eight of these are classed as “essential”, and twelve are “non-essential”. The difference between these two classifications are based on whether your body can make a particular amino acid. The body cannot synthesize any of the eight essential AAs, and as such require these AAs from our diet. (1, 7, 10)

This brings us to protein completeness classifications. A protein is considered a complete source if it contains all essential AAs, regardless of the number of non-essential AAs. Following from that, a protein source is considered incomplete if it doesn’t have all essential AAs present. The number of AAs in quantity and type determine a protein source’s AA Profile. To give a few examples: All animal proteins are complete sources, along with a select few plant-based sources like Quinoa. Incomplete sources include Tofu and mushrooms. That doesn’t mean you can’t satisfy the full requirement of AAs from non-animal sources, you just need to be aware of what AAs come from which plant-based source and mix-and-match accordingly. (2, 7, 10)

Satiety and Satiation (10)

Finally we come to one of the most significant and underrated aspects of dietary protein - Satiety. Satiety means how well a particular food satisfies the feeling of hunger during a meal. Satiation is the same idea, but specifically between meals (i.e. how long hunger is absent after eating). Taking a bird’s eye view of our macronutrients, fats are have the lowest satiety and satiation, Carbs have high satiety (You feel full and satisfied while eating them) but low satiation (you quickly feel hunger again following a high-carb meal), and protein has equal-if-not-higher satiety to carbohydrates, yet also has high satiation. This means that protein: a) satisfies you the most during a meal and, b) keeps you fuller for longer. Combined with the fact that protein has less than half of the calories (per gram) that carbs and fats contain, you’ve got one heck of a silver bullet to add to your dietary toolbelt.

TEH APPLICATION

All of this is exactly why we LOVE protein at Pro.G.I.. There is so much more to get into on this subject, but we’ve already covered a heap. What I really want for you is to have 2-3 concrete applications from this article that you can take on-board and implement into your diet and lifestyle to make a substantive and positive impact in your life. That being said, here are 3 easy ways to take the 2000+ words written here and actually use it for something.

1. Increase the amount of protein in your diet. Duh.

This sounds easy, and a bit of a no-brainer - so why haven’t you done it yet?! Take what you would normally eat in a day, then consciously and deliberately get rid of ~10% of both the fats and carbs, and add in 20% more protein. You’ll likely find that you can’t fit in the amount of extra protein because of how filling it is! A fantastic way to do this is to replace your snacks in-between meals with some beef jerky or biltong. Even better? Pro.G.I.! This is why Pro.G.I. was created - to provide an extremely high-quality, high-protein, high-taste meal replacement and snack.

2. Understand your protein source’s amino acid profile.

More important for non-animal product eaters, understanding which essential AAs you’re getting and which you’re missing is crucial for maintaining a healthy balanced diet. You might be feeling much worse than you should be without knowing! Even worse, you could be low on an AA that works to enhance bone strength, for example.

This also has use for those of us who supplement our diets with protein. If you purchase protein supplements make sure that you know where these companies supply their product from and whether they use a filler. Look for supplements with very low ingredient lists (1-2 ingredients) to ensure you’re getting the highest quality protein powder.

3. Don’t worry about the outputs - focus on the inputs!

Don’t stress about the numbers on a scale - focus on what you’re putting into your body! This applies not just for your diet but nearly all of life. If you control what and how many calories you put into your body, the results will come! Pro.G.I. is an effective tool that makes this easy, but you can do this with everything you eat and drink for maximum results.

Whatever you do, the key is that progress is made with 1000 tiny changes over 1000 days. Ok, maybe not 1000 changes and 1000 days exactly, but the idea is that making huge sweeping changes, while necessary in some cases, will rarely make lasting change. If you really want to find improvements in your health, pick a couple of key principles and stick to them for 6 months. Be patient, cut yourself some slack not to change all at once, and EAT MORE PROTEIN!!

Or not, totally up to you!

Here are the promised sources. PLEASE do be sure to check these articles out to learn more about what protein can really do!

References

Barrett, G. (Ed.). (2012). Chemistry and Biochemistry of the Amino Acids. Springer Science & Business Media.
Campbell, W. W., Barton Jr, M. L., Cyr-Campbell, D., Davey, S. L., Beard, J. L., Parise, G., & Evans, W. J. (1999). Effects of an Omnivorous Diet Compared with a Lactoovovegetarian Diet on Resistance-Training-Induced Changes in Body Composition and Skeletal Muscle in Older Men. The American Journal of Clinical Nutrition, 70(6), 1032-1039.
Cruz-Jentoft, A. J., & Sayer, A. A. (2019). Sarcopenia. The Lancet, 393(10191), 2636-2646.
Gastin, P. B. (2001). Energy System Interaction and Relative Contribution During Maximal Exercise. Sports Medicine, 31, 725-741.
Godfrey, K., Robinson, S., Barker, D. J. P., Osmond, C., & Cox, V. (1996). Maternal Nutrition in Early and Late Pregnancy in Relation to Placental and Fetal Growth. British Medical Journal, 312(7028), 410.
Hiller-Sturmhöfel, S., & Bartke, A. (1998). The Endocrine System: An Overview. Alcohol Health and Research World, 22(3), 153.
Hoffman, J. R., & Falvo, M. J. (2004). Protein–Which is Best?. Journal of Sports Science & Medicine, 3(3), 118.
Lambert, C. P., Frank, L. L., & Evans, W. J. (2004). Macronutrient Considerations for the Sport of Bodybuilding. Sports Medicine, 34, 317-327.
Müller, T. D., Nogueiras, R., Andermann, M. L., Andrews, Z. B., Anker, S. D., Argente, J., Batterham, R.L., Benoit, S.C., Bowers, C.Y., Broglio, F., Casanueva, F.F., D’Alessio, D., Depoortere, I,. Geliebter, A., Ghigo, E., Cole, P.A., Cowley, M., Cummings, D.E., Dagher, A., Diano, S., & Tschöp, M. H. (2015). Ghrelin. Molecular metabolism, 4(6), 437-460.
Paddon-Jones, D., Westman, E., Mattes, R. D., Wolfe, R. R., Astrup, A., & Westerterp-Plantenga, M. (2008). Protein, Weight Management, and Satiety. The American Journal of Clinical Nutrition, 87(5), 1558S-1561S.
Powers, J. D., Malingen, S. A., Regnier, M., & Daniel, T. L. (2021). The Sliding Filament Theory Since Andrew Huxley: Multiscale and Multidisciplinary Muscle Research. Annual Review of Biophysics, 50, 373-400.

PROTEIN, CARBS, FATS, SATIETY, AND THE ENERGY SYSTEM!

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