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Protein 101: What it is and Why You Need Plenty of it For Muscle Growth

Essential for building new tissue and repairing damaged tissue, protein is the major building block for all the cells of our body, and is involved in virtually every process within these cells. In short, protein is critical for our very survival.

As fundamental components of all living things, proteins comprise substances such as hormones, antibodies and enzymes – all crucial for the proper functioning of our bodies. As the hardest working molecules we have, proteins work overtime to ensure many of the chemical processes within our cells are carried out in an efficient fashion. While some proteins signal cell receptors to turn various processes on or off, others are charged with carrying certain molecules around the body, like for example, hemoglobin, which is perfectly shaped to bind with oxygen after which it’s carried to the tissues that need it most, such as the brain. Whether our needs are basic, or we are elite athletes needing to recover from arduous training sessions, we all require a certain amount of protein in our diets. Without sufficient protein we may, over time, waste away to nothing. A perfect ratio of dietary protein not only sustains life but can enhance athletic performance and favorably increase our body composition to make us big and strong.

Protein as Fuel

Protein also provides a fuel source – at four calories per gram its energy content is on par with carbohydrates, though, unlike carbs, it’s not the body’s preferred source of energy (remember, it’s a builder). Aside from building tissues and providing energy, protein also assists in weight management; by increasing protein from 15 to 30 percent of daily calories consumed, the spontaneous consumption of carbohydrates (a leading cause of obesity), and appetite, can be significantly decreased.

Given that the breakdown, digestion, and synthesis of protein expends a great deal of energy, the consumption of protein can result in an increased metabolic rate and further fat loss.

Protein MoleculeCompositionally speaking, protein is a complex organic macromolecule which contains carbon, hydrogen, oxygen and nitrogen (its distinguishing component), and is comprised of one or more polymer chains of amino acids linked together in specific sequences (certain sequences represent different protein types and their functions). Higher quality protein sources contain more of the so called “essential” amino acids, whereas low grade protein provides more “non-essential” amino acids. Given that the body cannot manufacture essential amino acids on its own, it’s best to consume proteins which for the most part contain this variety.

Protein Requirements & Timing

Our protein requirements change the older we get and fall in line with how physically active we are; so whereas infants require around 10g of protein per day, adult men and women need, on average, 56g and 46g per day respectively (around 17%-21% of daily calories). The fact that you’re reading this article suggests that you’re a bodybuilder, strength athlete, or an otherwise physically fit and active person. The percentages quoted above would therefore, in the context of your own requirements, appear absurdly low – in fact, 56g of protein is barely enough to sustain the average 200lb athlete during the muscle repair process for a 2-4 hour period.

For the average healthy person (or non-lactating or pregnant woman, who requires 71g or more per day), 50-60g of protein spaced out over a 24 hour period is the medically accepted average. In reality, most of us easily consume around 100g of protein per day (one chicken breast comprises about 35g of protein, a glass of milk around 10g, three slices of whole grain bread close to 10g).

Optimal Protein Consumption For Growth

Bodybuilders and strength/endurance athletes, given the physically demanding nature of their sport and the ongoing repair and rebuilding of their muscle tissue, need as a conservative estimate, around 2.5 times more protein than the average person. Among serious weight trainers, the accepted rule of thumb for daily protein consumption is 1-1.5g of protein per pound of bodyweight (our 200lb bodybuilder would therefore need around 200-300g per day). Though the jury is still out on exactly how much protein is enough for optimal muscle growth, we would be wise to err on the side of more rather than less.

Whenever we work a muscle to exhaustion with heavy weights, minute tearing occurs within its individual fibers; insufficient post-training protein consumption will delay, if not completely curtail, this muscle’s healing process.

Under such catabolic conditions our muscles may not only fail to fully heal, and grow larger and stronger, they may further break down and lose size. Sufficient protein is therefore essential to ensuring that protein synthesis occurs following hard training sessions. So if size gains are what you’re training for, saturate your system with enough amino acids (from protein) to get the job done. Key times for protein consumption are first thing in the morning (when nitrogen retention – an indicator of the extent to which protein is biologically available to support muscle growth – is extremely low) and during and directly after intensive training (when our muscles are most receptive to storing protein for rapid protein synthesis and faster recovery).

Classification of the Two Main Amino Acid Types

Essential Amino Acids

These must be supplied though a person’s diet as they cannot be manufactured by the body. Check the nutritional profile of the foods and supplements you consume to ensure they contain a full complement of essential amino acids. The nine essential amino acids are:

  1. Histidine
  2. Isoleucine
  3. Leucine
  4. Lycine
  5. Methionine
  6. Phenylalanine
  7. Threonine
  8. Tryptophan
  9. Valine

Non-Essential Amino Acids

These are made by the body from essential amino acids, or through the breakdown of proteins. If the foods you consume contain amino acids mostly of the non-essential type, you may need to supplement your diet so as to include more of the essential kind. The 12 non-essential amino acids are:

  1. Alanine
  2. Cysteine
  3. Cystine
  4. Glutamine
  5. Glutathione
  6. Glycine
  7. Histidine
  8. Serine
  9. Taurine
  10. Threonine
  11. Asparagine
  12. Apartic acid
  13. Proline

Evaluating Your Proteins

Which Types Are best?

At face value, the total protein composition of a food is not the best indicator of whether it will promote quality gains in muscle size or even the maintenance of good health.

First of all, lean protein sources are preferable to those containing significant amounts of fat, such as those found in fast foods and fatty meats. A lean protein source will be better assimilated and more efficiently used by our tissue than one containing a great deal of fat.

Secondly, to be considered high quality, proteins must comprise a high percentage of essential amino acids, and the total usable protein content of a given type must also be high. A reliable indicator of whether a protein source could be considered a good, or bad, option or has a large distribution of usable essential amino acids is its combined Biological Value (BV), Protein Efficiency Ratio (PER), and Net Protein Utilization (NPU) reading.

Biological Value (BV)

When assessing a protein’s quality, the first major indicator to consider is its biological value, or, bio-availability. This will tell us how efficiently our bodies can use this protein – it’s the percentage of a given protein source that the body is able to absorb and utilize. Protein sources are generally ranked according to their BV (or how bio-available they are once consumed).

Once the gold standard, eggs, with a rating of 100, have since been overtaken by whey protein, with its ranking of 104, and whey isolate, which ranks at a hefty 159.

Lower on the list are: chicken/turkey (79), casein (77) beef (69), cow’s milk (60), brown rice (57) and soy beans (47 – soy protein has a BV of 74).

Nitrogen, a key element within protein responsible for tissue growth and the governance of many biological functions, accumulates in greater quantities, thus resulting in more beneficial enzymes (to aid with food digestion, protein synthesis and to catalyze metabolic processes), whenever we consume higher quality protein sources. Thus, measuring nitrogen retention (by assessing the amount contained in one’s diet minus that extracted in urine over a 24 hour period) is an effective way to determine whether we have consumed enough high BV proteins.

Protein Efficiency Ratio (PER)

Yet another way to measure a protein’s quality is by determining its protein efficiency ratio, or the rate at which an individual protein can sustain growth (determined in the lab by taking the weight, in grams, gained by a protein-fed test subject and dividing it by the amount, again in grams, of the specific protein this subject took). Given that the quantity of one protein may promote greater weight gain compared to the exact quantity of another, it’s worth knowing which is which to ensure greater gains of our own. As one might expect, whey proteins score highest with a PER of 3.9. Eggs clock in at 3.1, fish, beef and chicken at 2.7, cow’s milk and casein at 2.5, soy at 2, and rice at 1.5. 

Net Protein Utilization

To ensure the proteins we consume are absorbed into our bloodstream at an efficient rate we must first assess their digestibility and utilization. The percentage of protein retained by the body after the digestion of a protein-containing foods is that food’s net protein utilization.  However, one caveat applies – while certain foods such as beef and chicken may have the exact same PER and be similar in their BV and NPU, beef, with its higher percentage of fat, may not be absorbed as fast (chicken also contains around half the calories of an equal serving of beef).

A list of common foods and supplements and their respective NPU percentages:

  • Whey protein: 92%
  • Eggs: 88%
  • Fish: 78%
  • Beef and chicken: 68%
  • Soybeans: 48%
  • Brown rice: 40%
  • White bread: 20%

The Best Protein Sources for Bodybuilders

Supplemental Protein and Timing

For rapid assimilation and quick fire muscle gains, whey protein has become the standard by which all other protein sources are now measured. A quality whey supplement (like ISOFLEX Whey Protein Isolate) can be used pre, intra and post workout, to infuse your muscles with high grade essential amino acids. A workout without a generous 25-30g serving of whey is, in today’s more enlightened age, considered a wasted workout. Whey is also recommended in the early morning to offset any potential muscle catabolism brought about through a  sleep-induced 8-10 hour fasting period.

Casein vs. Whey

As noted above, while whey protein scores highest in all three measures of protein quality, casein is ranked lower than many common whole food sources. However, this doesn’t mean that both do not have an important role to play in muscle growth. As many a bodybuilding champion will attest to, both are not only desirable, they are essential. Here’s why.

Casein – a milk protein – is, upon consumption, more slowly released compared to whey. This makes it the perfect antidote to the 8-10 hour fast we are forced to undertake during sleep. Taken immediately before retiring for the night, casein will stay in the system longer, shuttling valuable amino acids into our muscles while we sleep. A good casein product (such as ALLAMX’s Casein-FX, which also supplies a hefty serving of glutamine and is of the preferred micellar and calcium caseinate type) is essential for those wanting around the clock muscle gains.

Whey and casein can also be combined to ensure both fast and slow release proteins are on hand to keep one’s muscles anabolic for longer. As the perfect solution, ALLMAX’s newest product, HEXAPRO, with its six protein blend (whey isolate, whey concentrate, egg albumen, milk protein concentrate, micellar casein and hydrolyzed whey), and five amino acid blend (with BCAAs), can be taken at any time to flush the muscles with all the protein they need to grow. In fact, many are now using HEXAPRO almost exclusively as a one-stop protein product that is both convenient and effective (and delicious).

Whole Foods vs. Supplemental Protein

A long standing debate – which is better, protein from whole foods or from supplemental sources? The answer is… both.

Protein supplements have taken their rightful place as the most reliable and efficient source for rapid protein consumption which supports maximum muscle growth. In addition, there’s the convenience factor – it makes sense for the busy gym rat to fire down a quick protein shake prior to, and after, intense workouts. It’s at this time when protein requirements are at their peak, both to stave off catabolism and to flood hungry muscles with essential amino acids for growth and recovery. Whole food is just not practical in this scenario.

However, whole foods are of equal importance – they supply many important co-factors that protein supplements may not. Beef, for example, can provide a natural source of creatine, saturated fats (which can be useful for testosterone production), B-vitamins and a host of trace minerals for proper cellular functioning. Eggs and fish, with their superior protein content, essential fatty acids (EFAs) and high BV, are widely considered the perfect muscle-building foods. And finally, for those of us who actually enjoy cooking, food is both a source of great pleasure and a way to add spice to one’s life. The ideal compromise, it seems, is to use protein supplements strategically (3-4 times per day, in and around workouts, first thing in the morning and before bed) and employ whole food sources at all other times.


In view of the combined BV, PER and NPU of our most commonly consumed protein-rich foods it appears that, in order of effectiveness, whey protein (preferably the isolates), eggs, fish, chicken, beef, cow’s milk and casein trump all others. Therefore, when planning your nutritional requirements, be sure to ensure the best of these comprise the majority of your diet.

Whether we prefer to achieve an optimal intake of it in supplement form or through the consumption of whole foods, high quality proteins that are rich in all nine essential amino acids are a fundamentally important prerequisite for all hard training bodybuilders and strength athletes. Given that our muscles, and indeed all the cells of our bodies, are comprised of proteins, we need plenty of these in nutritional form to repair and build a solid and more efficiently functioning foundation. Remember, if you want to look like a bodybuilder, you need to eat like a bodybuilder, and one of the keys to this mantra is maintaining an adequate ratio of protein in a well balanced diet.


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David Robson

A respected health and fitness writer, David has been published in industry publications such as Status Fitness Magazine, Muscle & Fitness and Bodybuilding.com. With 20 years in the personal training trenches, the insights he has gained through practical experience, alongside degrees in psychology and sports science, have enabled him to go beyond the surface to provide educational articles that have informed thousands of health and fitness devotees the world over. Contact David at: davidrobson19@hotmail.co.nz and at davidrobsonelite.com