Understanding protein: intakes, supplementation, benefits and risks (Part I)


Mention supplementation to any aspiring athlete or just anyone who tries to work out even just lose body fat – and the first thing that they think of is protein shakes.  Protein supplementation became so synonymous with exercise nutrition and perceived to be so necessary and indispensable that it is considered by many a panacea and a miracle substance that would work wonders and magically reshape the body into fit, athletic and beautiful.

Protein shakes are marketed as meal substitutes for various diet plans.  Because proteins are typically thought of as “building blocks” for muscle and, for many people, are associated purely with muscle growth – literally, huge buckets of protein powders (with boastful names claiming to provide some mega-hyper-anabolic muscle mass effect), can be purchased at supplement stores, drugstores and regular supermarkets.

In fact, protein – readily available in the form of shakes, snack bars and other foods – has become so ubiquitous that few people question the actual need to consume more or the reason for it.  Many automatically assume that healthy nutrition to support any athletic goal starts with protein shakes and expect almost magical results – from weight loss, to instant lean muscle mass.

How justified is this belief in the necessity to consume copious amounts of protein if you want to be lean and fit?  Does more protein consumed automatically translate into more muscle (and less fat)?  Do you actually need extra protein supplementation and, if yes – what type of protein and in what amounts do you need?  Is there a difference between different types of protein and any specifics to look out for?

All of these questions will be answered in this series of articles – so keep reading to learn whether protein plays an important role in helping you reach your peak athletic form – and how get the most benefit from your protein consumption in a way that promotes, and not undermines, your health.

What is protein?

Despite its widespread use, not a lot of people actually understand what the word “protein” actually stands for.  In fact, protein is not one specific compound – it is a generic name for a wide variety of organic molecules that consist of any combination of the 20 physiologically-relevant nitrogen-containing amino acids.  Your body can synthesize 11 of those amino acids on its own, but the remaining nine (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) are not synthesized by mammals and can only be obtained with protein-rich food – these are commonly called essential amino acids.

Amino acids are typically linked into peptide chains, which, in turn, are further linked into proteins.  As a result, proteins can be simple – containing only a few amino acids – or quite complex, containing 50 or more individual amino acids (the record is held by titin, which contains 34,350 individual amino acids in one protein molecule).  The final shape of proteins (which is determined by how individual peptides and amino acids in the protein chain bond to form a “folded” three-dimensional structure, can be extremely complex (and can even contain “knots”) – but it is often precisely that shape that determines protein’s biological function.

Proteins, although synonymous with sports nutrition and athletic performance, actually perform many functions in the body – they play a structural role (e.g. keratin in hair and nails and collagen in joints and connective tissue), control movement (e.g. contractile proteins facilitating muscle contractions), work as enzymes catalyzing thousands of chemical reactions within cells, function as anti-bodies that fight invader viruses and bacteria, serve as messenger molecules that coordinate chemical reactions between different tissues and organs, serve as precursors to some hormones (e.g. insulin), transport and store other molecules (e.g. haemoglobin that transfers oxygen through blood), etc.

So, obviously, life as we know it is impossible without protein.  In fact – that’s pretty much all your DNA does: the genetic code stored in it, with individual genes coding for specific proteins, defines the structure – and, thus, type and function – and location of protein that get synthesized (only a few genes produce other molecules that help assemble those synthesized proteins).

Protein digestion and metabolism

When you consume proteins with food (or in their concentrated form through supplementation), your digestive system breaks larger protein molecules into individual peptides and, further – into individual amino acids (and some – even further into individual atoms and atom chains).  These amino acids serve as building blocks for assembling proteins that your body needs (the liver and, to a lesser extent, kidneys are the principal sites of amino acid metabolism in humans) – they are further delivered through bloodstream to their final destination or to the liver for synthesis and utilization.

Your body, however, lacks a way to “store” amino acids consumed in excess of the amounts needed for the synthesis of nitrogenous tissue.  Such amounts needed, however, can fluctuate significantly based on various factors.  For instance, children and pregnant and lactating women have an additional requirement for protein for tissue growth or milk formation.  Similarly, athletes recovering from training have elevated demand for protein just to counter the effect of muscle catabolism (tissue degradation) following strenuous exercise.

So, given that amino acids are not stored for future use, if you consume too much protein – those excess amino acids are degraded, the α-amino group is removed and the resulting carbon skeleton is metabolized into pyruvate, acetyl-CoA or one of the intermediates of the tricarboxylic acid cycle.  The nitrogen is then excreted as urea, and the keto acids left after removal of the amino groups are either utilized directly as sources of immediate energy, or, when there are no immediate energy needs, are converted to carbohydrates and – if those cannot be utilized for current energy needs or to replenish depleted glycogen reserves – further converted into body fat.

Conversely, protein deficiency is a rare occasion and is not an isolated condition – it is typically a deficiency of dietary energy and other nutrients in general, resulting from overall insufficient food intake. Exceptionally low protein intake is rare in developed countries and is easy to spot by accompanying physical signs—stunted growth, poor musculature, thin and fragile hair, skin lesions, etc.

High-protein diets

Given importance of protein for life , nobody ever questions the necessity of dietary protein.  No matter what camp you are in – low-carb or low-fat, when it comes to diets, consumption of protein is usually relatively comparable between the two.  Some diets even specifically promote notably high-protein consumption.

Statistics show that on average, American males aged 20-49 consume between 106 and 118 grams of protein per day, while females of the same age consume between 72 to 75 grams.  That is not a small amount of protein – especially compared to the recommended averages!

So why isn’t everyone built like Muscle and Fitness magazine cover model?

Because excess protein is not automatically stored in your muscles if they don’t have any need for it (i.e. – if they are not recovering from catabolism).  Your muscle tissue is, in a sense, your emergency protein storage pool – and your body typically taps into those storage reserves when you starve, get sick or otherwise face elevated demand for proteins – in cases like that muscle tissue gets catabolized and resulting amino acids get re-used for synthesis of other relevant proteins.  But muscle tissue really is an emergency reserve and is not intended to be used to supply protein for metabolic needs (otherwise, severe muscle-wasting would follow).  Conversely, muscles are not intended to accumulate excess protein for such emergency use.

Generally speaking, under conditions of adequate nutrition your body tries to maintain homeostasis and balance protein breakdown rate with protein utilization rate.  In other words – protein gets constantly broken down, reassembled and re-utilized.  In fact, research shows a unique situation where, as compared to carbohydrates and triglycerides, proteins have the fastest turnover rate and the lowest oxidation rate.

We should probably mention the counterproductive effect of excessive protein taken in an attempt to change body composition – those who supplement with protein (or just eat too much of it) typically have a goal of increasing lean muscle mass while decreasing fat mass.  As we have seen, excessive unneeded protein will be eventually converted into body fat, undermining all your body re-composition goals. The premise of many high-protein diets is that the resulting satiety would automatically reduce the consumption of carbohydrates and fat, thus decreasing the risk of weight gain.  But – given how proteins can be converted into glucose through gluconeogenesis – and how excess glucose can be converted into body fat – consumption of excess protein is a generally one of the ways to actually gain body fat.

High-protein intake has some other potential associated risks.  First, protein metabolism increases ammonia levels in the body.  While ammonia is very toxic and, at high levels can cause brain damage, typically, this is not a problem, as a healthy liver would rapidly convert ammonia into less toxic urea, which is further excreted through kidneys.  But if any of these organs (liver and kidneys) have any problems, the amount of ammonia or urea can build up (that’s why people with kidney problems are advised to limit their protein intake to about half of the recommended averages).  That being said, when it comes to absolutely healthy organs – studies (like this study on bodybuilders consuming a high protein diet – 2.8 g per kg of body mass each day) have found no evidence of protein toxicity due to high protein intake on kidney function.

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The second risk associated with unnecessarily high protein intake is the increase in IGF-1, secreted by the liver.  IGF-1 (Insulin-like Growth Factor 1) is an anabolic hormone that modulates cell growth and survival.  Although IGF-1, necessary to support normal growth and development – including mental development – is not inherently bad (read the article on IGF-1 and associated risks – or lack thereof) – unfortunately, increase in its levels also may potentially mean an increase in the risk of cancer cell growth (unless there are other mitigating factors, which is often key).  And because proteins (and, to an extend – lipids) seem to increase IGF-1 levels, excessive consumption of protein in the amounts consistently higher than what your body needs may elevate risks associated with too much IGF-1.

Then there is a concern that significant increase in protein intake increases calcium excretion in urine, leading to a negative calcium balance – this leads to the loss of bone mineral density and increases the risk of osteoporosis and subsequent fractures.  The mechanism behind this is likely related to the increase in acid secretion due to the elevated protein consumption.  Bone acts as a reservoir of alkali, and, as a compensatory mechanism, calcium is liberated from bone to buffer high acidic levels and restore acid-base balance.

However, this has been observed mostly when protein intake increases and phosphorus intake remains constant. If phosphorus intake increases with increased protein intake, calcium excretion is greatly minimized.  Typical sources of animal (meat, fish, dairy) and plant (beans, peas, etc.) protein contain sufficient amount of phosphorus, so if the increase in protein is due to whole protein-rich foods, it is typically automatically balanced by an increase in phosphorus intake.

In the end, the system for disposal of excess nitrogen is quite efficient.  You may or may not have an elevated need in higher amount of protein – and while you should err on the side of caution, protein intakes moderately above requirement are believed to be safe.  So what would your actual requirement be?  We will discuss this shortly.

Low protein diets

But if you thought decreasing your protein intake is the answer to all problems – think again.  Protein intake is probably the most difficult to dial in because, while it is true that taking too much of it may potentially lead to several problems described above, taking too little will lead to even bigger problems.

If you do not exercise specifically and do not have an active lifestyle that has your muscles working one way or the other (if this is the case – change this immediately) – your protein requirements are probably much more modest than those of an elite athlete.  But – especially for certain age groups – underconsumption of protein actually becomes a bigger issue than overconsumption.

As an example, a lot of kids, teenagers and seniors do not consume adequate amounts of protein.  Why this might be happening is a separate question.  One theory we have is that kids these days get so overloaded with carbohydrate-laden foods that protein just gets neglected amidst glucose and insulin spikes and quick sugary or starchy snacks.  Teenagers face the same problem, but also succumb, inspired by podium models, to fad diets essentially based on calorie restriction and malnutrition in general, while seniors – just as many teenagers – intentionally or unintentionally follow calorie-restricted diets and also face higher rate of age-related sarcopenia and hormonal decline, making it harder to retain muscle and shed body fat, but also increasing the need in protein to counteract this process.  In any case – the reality is that in some cases and for some population groups, the daily dose of protein should actually be increased.

Remember, as we mentioned above, cases of severe protein deficiency are actually very rare in developed countries.  In those countries or cases where it does exist, it is a general malnutrition problem, rather than a deficiency of a specific macronutrient.  Mild deficiency, however, can be very real – and what this will lead to is probably not something you want.  It would almost certainly mean muscle wasting as your body stops holding on to metabolically-expensive muscle tissue and, instead, starts utilizing these internal “reserves” to break them down and re-use the resulting amino acids – but also organ malfunctions (as, in extreme cases, organ proteins can also be broken down for immediate needs).  It might mean hormonal changes (for the worse, of course), skin hair and nail problems and even fatty liver disease.

Protein deficiency doesn’t have to mean you consume less protein in general.  It might also mean, you consume very little of “complete” protein sources that contain all essential amino acids (remember your body cannot produce or re-synthesize those from other amino acids and they need to arrive with food), while overloading on non-essential ones – so, while you might be getting enough (or even too much) of total protein, the actual variety of amino acids (or lack thereof) in imbalanced diets can be an issue.  Generally, if you consume animal protein (meat, poultry, fish, eggs, etc.) – this problem will not exist, as those animal sources almost always contain complete proteins with all essential amino acids.  But in vegetarian and, even to a greater extent – vegan diets – this problem can become quite serious if not specifically addressed.

People who restrict their diet to plant food may be at risk of not getting adequate amounts of some indispensable amino acids (lysine, methionine, cysteine, threonine).  And while, in theory, consuming a variety of plant-protein containing products can still provide essential amino acids in combination (where some essential amino acids come from one plant and some others come from additional plants), keep in mind that plant proteins (as we previously discussed), typically have lower scores when it comes to digestibility, efficiency, biological value and utilization, so you generally need more of them by quantity.  One fundamental problem with this approach is that whole food-based plant sources of protein (unless in concentrated/isolated form) are also significantly loaded with carbohydrates (and some popular sources like soy or wheat – also loaded with hormone disruptors, such as goitrogens and phytoestrogens, phytates and lectins and other stuff you can totally live without.

Muscles are not the only tissue affected by low protein intake – low-protein diets also decrease bone density, increasing the risk of fractures.

So, do you actually need more protein?  And if yes – how much?

If you have any kidney or liver abnormalities – all bets are off and any potential risk of higher- or lower-protein intake needs to be evaluated against your current health situation (in other words – consult a good doctor).  But if you are generally healthy – the question still remains: do you need extra supplementation?

As with many questions, the answer is the usual: “it depends”.

Health authorities recommend a mean amount of about 0.61g of protein per 1 kg of body weight per day.  In all fairness, this is a loosely defined measure because body weight does not define body composition – someone who has an extra 200 pounds of body fat has no business calculating protein requirements based on their total weight – as discussed above, this enormous amount of protein will simply convert to fat (and, potentially, put quite a bit of strain on kidneys, adding fuel to the fire in the environment defined by potential systemic inflammation, metabolic deficiencies and clear overconsumption of bad foods.

The actual recommendation around whether you need more or less protein depends on many things – the type, quality and digestibility of proteins you consume, your lifestyle, genetics, current and future athletic goals, etc.  You should now understand the importance of getting enough protein (not too little, not too much), but how do you determine how much is “enough”?  What are the cases when you need to increase or reduce your consumption of protein and, most importantly, if you are considering supplementing – what type of protein should you supplement with?

Let’s look at a few important considerations and discuss a few specific proteins that might help you make that decision.

Protein and exercise

There is an inordinate number of myths and misconceptions surrounding protein and exercise.  As a result, the exercising community typically consumes quite a bit of it – often more than necessary.  Quite often new adepts start consuming protein shakes way before their consumption is warranted in any way or in amounts that significantly exceed their needs because they have heard that “protein is good for building muscle”.

The assumption is that you, being a frequent visitor to this website, understand the importance of resistance exercise (if you don’t – re-read articles in the Exercise section) and regularly engage in brief bouts of strenuous physical activity.  So, most probably, conventional recommendations regarding recommended daily averages of protein would not apply to you, because your muscle tissue will have a greater need for protein simply to rebuild tissue damaged during exercise and, through such subsequent adaptation, make it more resilient, stronger and bigger.

(By the way, if you – whether you are a man or a woman – are not convinced about building muscle – and we are not talking hugely exaggerated body proportions – you should definitely read this article)

Studies examining strength-trained individuals demonstrated that higher protein intakes have generally been shown to have a positive effect on muscle protein synthesis and size gains.  It has been demonstrated that for strength trained individuals to maintain a positive nitrogen balance they need to consume a protein intake equivalent to 1.8 g/kg of body mass per day – and some showed that within four weeks of high protein supplementation (with 3.3 g versus 1.3 g per kg of body mass per day ) in subjects engaged in resistance training, significantly greater gains were seen in protein synthesis and body mass.

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Other studies also report a greater protein synthesis in novice resistance-trained individuals with protein intakes of 2.62 g. versus 0.99 g per kg of body mass per day, suggesting that protein intake recommendation also depends on what stage you are at in your training – this makes sense as, with increased muscle adaptation, they do not experience as much exercise-induced catabolism to begin with).

The recommendation for higher protein intake is not just for strength athletes – endurance athletes also appear to require a greater protein consumption to prevent significant losses in lean tissue.

In a way, moderate overconsumption of protein for people who constantly set more challenging athletic goals for themselves and generally follow a clean diet is quite forgiving – your body has a unique ability to convert excess protein into glucose for immediate energy or for storage as glycogen or fat.  Carbohydrates and lipids supply most of the energy needs during exercise, but human skeletal muscle can also oxidize at least seven amino acids (leucine, isoleucine, valine, glutate, asparagine, aspartate and alanine), providing additional free energy to fuel muscle contraction. The major sites of gluconeogenesis – liver and kidneys – can also convert certain amino acids into glucose for energy.  In addition, amino acid catabolism during exercise increases citric acid cycle intermediates and therefore supports carbohydrate and lipid catabolism.

Because of higher energy requirements following resistance exercise (and, as we have previously discussed your muscles continue to burn more energy in the process of tissue recovery and regeneration for up to 72 hours following resistance exercise), even if you slightly overconsume protein and end up with excess amount – even if it is converted into glucose – chances of that glucose contributing to your body’s fat reserves in the long term are much slimmer.  This converted glucose is much more likely to be used for immediate (and elevated) energy needs.

This is not to say that protein should be consumed for specifically for energy  – this is to say that moderate overconsumption under conditions of elevated energy requirements will, most probably, have this excess protein effectively utilized.  Of course, if you supplement extra protein with extra fat and extra carbs – immediately available glucose will be used first – which increases the chances of extra protein being converted into glucose your body won’t need any more and thus, further – to fat.  In addition, if you are concerned about any negative consequences of excessive protein consumption where it is not warranted – this is probably not the best strategy.

If, on the other hand, you exercise and do not consume adequate amount of protein – you will see no muscle tissue growth.  In fact, you may even start losing muscle, as it gets catabolized during exercise and lacks adequate nutrition to get rebuilt after – research shows that physical exercise by adult humans is accompanied by an increase in the rate of whole protein breakdown and a decrease in the rate of synthesis, so you have to do something to counteract this process.

So, the bottom line is – exercise definitely increases the need in protein (so if you are planning to stick to the recommended RDA of 0.62g per kg of body mass – this is probably not going to work), but while covering this higher demand is a necessity of sorts, exceeding the amount that can actually be utilized is ineffective and may even be counterproductive.

How much more protein do you need if you exercise?  Again, the question is not straightforward.  It really depends on how much muscle you currently have (more muscle currently means potentially higher requirement as, if you engage in whole-body resistance exercise, more of that tissue gets potentially broken down), the type of exercise (heavy lifting that is initially more damaging for muscle than, say, metabolic conditioning exercise would require more protein for recovery and growth), general macronutrient ratios in your diet (as discussed above, higher level of carbohydrates in your diet leaves less of a margin for error when it comes to protein, unless you want to accumulate body fat) and other factors.

The best approach for athletes of both genders, therefore, is to calculate your daily protein requirements starting around 1g per 1kg of target lean body mass.  “Target” and “lean” are not just random words – they mean that you estimate your body fat percentage (no need to be overly precise) and subtract the respective weight from your total weight and then incorporate your goals to grow lean muscle tissue into this.

Example: if you weigh 85 kilos and are at about 20% body fat, your lean mass is 85 – (20% x 85) = 68kg, suggesting 68 grams of protein per day.  If you want to grow lean muscle mass (excluding body fat) from 68 to, say, 75kg, you would consume 75 grams per day.

Remember, because actual protein utilization and requirements change with environmental factors – this is just a starting point.  It needs to be adjusted based on your results.  Ideally, with that starting point you would see gains in muscle size and strength (all of the above assumes you actually do resistance exercise, as opposed to just chugging protein shakes and sitting on the couch, of course).  If, following the recommendations above, you notice that you are gaining body fat – try reducing protein intake by 10-15% and, in 3-4 weeks, see if your body fat percentage decreases while muscles actually get bigger and stronger.  If, on the other hand, you start with these recommendations and see no results in about a month of exercising (assuming, once again, that you do not just exercise every day, but, instead, engage in heavy and strenuous exercise and then allow sufficient time for recovery – typically 2-3 times per week) – increase your protein intake by the same amount.

There are several things to keep in mind:

  • Protein requirements will increase with the increase in the volume of lean muscle tissue (naturally, if you base your estimated requirements on the weight of that lean muscle tissue);
  • The number one reason why people who expect an increase in muscle mass see no results is lack of adequate nutrition. Remember, exercise significantly increases energy and protein requirements.  If you get just enough protein, but not enough energy to support all the processes that take place in your muscles over a long time following your exercise session – there is a high chance that missing energy will be extracted from the same protein, making the amount you consume actually inadequate, as some of it will be converted into energy (glucose) instead.  If you consume adequate protein to support structural needs but accompany this with too much carbs – you will trigger body fat accumulation.  It is a delicate balance, so results need to be constantly monitored and nutrient intake adjusted accordingly.
  • There is a very popular belief among bodybuilders that you need to consume about 25-30 grams of protein every 3 or 4 hours (because, allegedly, your body cannot absorb more at a time). Some competitive bodybuilders go as extreme as waking up at night to “refeed” their muscle with some sort of a quick protein shake, driven by a fear that missing that re-feeding would lead to muscle catabolism (breakdown) and lack of results.  Most of this belief is a myth.  First, actual daily protein requirements, of course, differ based on circumstances (30 grams per serving may be too little for a massive 250-pound lean competitive bodybuilder and too much for a novice teenager).  Second, while it is true that overconsuming protein in one sitting can be counterproductive, eating more than 30 grams at a time is very difficult anyway – unless you make concentrated shakes with protein powder and manage to consume 3-4 servings.  If you are talking whole foods – forget it: you will feel full (and, possibly, sick) before you reach any high number.  Third – your do not start wasting your muscle if you do not eat for several hours.  In fact, some research shows that you can starve for a few days and still show no real signs of muscle wasting – especially if the protein you do eat during the time of reduced nutrient intake, happens to contain sufficient amount of branch-chain amino acids, or BCAAs, if your body is generally fat-adapted to tap into its own fat reserves and efficiently burn dietary fat you consume and keto-adapted to utilize ketones for vital brain and heart function (in fact, you might want to re-read the article on ketogenic diets and their effect on maintenance of lean muscle tissue).  If your body gets adequate nutrition during the day generally, there is no need to eat every few hours.  Follow your hunger (while maintaining a clean natural diet) and monitor your body composition – that’s all there is to it.

In Part II we will discuss specific proteins and the role they play in your health and fitness.

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