Proteins: From Plate to Muscular Physique

Is there a universal secret formula for building muscle?

Protein is found in every nook and cranny of your body. They’re complex macromolecules made of smaller units called amino acids linked to each other to form chains. There are 20 different kinds of amino acids which combine in various ways to produce proteins. The amino acid sequence in the protein determines its distinct three-dimensional biochemical structure and specific function.

When you eat food, your digestive system breaks down protein into individual amino acids. These are then absorbed and used by different cells to build other proteins. Let’s trace the pathway dietary proteins take, from your plate, through your gastrointestinal tract, into your circulatory system, and finally ending up in your muscles. From plate to physique, these proteins do marvellous things for your muscles and overall health.

PLATE: How does our body process proteins from the food we eat?^[1]

How do you like your eggs? Eggs are an excellent source of protein. We’ll use it to illustrate protein digestion and the absorption process. An egg, on average, contains between 5.2 to 7.5 g of protein.

1. Digestion of proteins in your mouth. The primary step in digesting an egg is chewing. Your teeth start slicing and grinding large pieces into smaller pieces that can be swallowed and passed through your oesophagus. Your salivary glands release saliva to lubricate and facilitate swallowing.
2. Digestion of proteins in your stomach. The smaller egg pieces proceed to your stomach from the oesophagus. Your stomach then secretes gastric juice that contains hydrochloric acid and the digestive enzyme pepsin. Hydrochloric acid denatures dietary proteins, unfolding or unravelling their three-dimensional structure to expose the polypeptide chains. A protein’s three-dimensional structure is vital to its function, and denaturation eliminates that function. As soon as proteins are denatured, the peptide bonds connecting amino acids are more exposed and accessible for enzymatic digestion. Enzymatic digestion is initiated by pepsin, a critical enzyme released by the cells that line your stomach. Pepsin starts digesting or breaking peptide bonds, producing shorter polypeptides. Peristalsis or muscular contractions in your stomach convert the partially digested proteins into a more uniform and soupy mixture called chyme.
3. Digestion and absorption of proteins in your small intestine. The majority of protein digestion happens when chyme enters your small intestine. The pancreas releases pancreatic juice that contains the enzymes trypsin and chymotrypsin into your small intestine. Trypsin instantly activates other enzymes called proteases. All these enzymes digest proteins and polypeptides down to amino acids. These amino acids enter the small intestinal cells lining the tract using active transport. There’s a variety of transport systems to shuttle the different kinds of amino acids into the bloodstream. Undigested proteins continue to move towards your large intestine, where they will be eliminated in the stools.

PHYSIQUE: It’s Time to Build Muscle^[2]

Absorbed amino acids in the blood are transported to your liver. From the liver, these amino acids may be used in a variety of ways:

1. Production of nonessential amino acids required to produce proteins.
2. Production of other compounds that contain nitrogen.
3. Conversion to fat as storage. There’s no available storage form for protein.
4. Conversion to glucose for energy.
5. Muscle protein synthesis. Protein synthesis is the amazing process of building new proteins from individual amino acids. It happens in all the tissues and organs in your body. Muscle protein synthesis is the specific process of producing new muscle protein.

Imagine a muscle being a brick wall. Muscle protein synthesis is adding new bricks (proteins) to the wall. This would signify that the wall will become taller and taller (muscle hypertrophy). However, there’s an opposite process operating in the background called muscle proteolysis (breakdown of muscle protein). This may be pictured as removing bricks from the wall.

1. What’s essential to note here is that muscle protein synthesis and breakdown are dynamic or always happening. They don’t stop, but their rate can decrease or increase depending on the state of your health and nutrition. The difference in the rate of these two opposite processes determines the change in muscle size. If protein synthesis is greater than breakdown, the wall becomes taller and more prominent, which means that your muscles are growing (increase in muscle mass). If protein breakdown overcomes synthesis, the wall becomes smaller, signifying that you’re losing muscle mass.
2. Your body's total amount of muscle proteins is far more significant than any other protein. There are mainly four major types of muscle proteins found in your muscle: stromal, myofibrillar, regulatory, and sarcoplasmic proteins. All of them combined represent the bricks on your wall. Approximately 40% of your body weight is muscle, and 20% of that is pure muscle protein.

How to Optimise Muscle Building through Proper Diet, Protein Intake, and Exercise^[3]

1. Keep track of your protein intake, including quality, quantity, and timing. Protein provides amino acids required for muscle protein production, which means focusing on high-quality protein sources with complete amino acid ingredients. Click here to learn more about quality protein sources. If your meal or food contains all nine essential amino acids in adequate amounts, it’s designated as a complete source of protein. Essential amino acids behave as signals to start muscle protein production. Make sure that your protein source contains a lot of them. They’re all needed for muscle protein production. The lack of one or more will blunt the muscle protein production response.
   How much protein do you need? Protein quality is essential, but quantity also plays a significant role. Use the table below to estimate your daily protein requirements to favour optimal muscle protein synthesis.
   
   

   RECOMMENDED DIETARY INTAKE (RDI) FOR PROTEIN

   Age	Men	Women
   19 – 30 years old 31 – 50 years old 51 – 70 years old	64 g/day (0.84 g/kg)	46 g/day (0.75 g/kg)
   > 70 years old	81 g/day (1.07 g/kg)	57 g/day (0.94 g/kg)

   
   The protein requirement for bodybuilders and athletes is expected to be higher, between 1.7 and 2.2 g per kilogram of body weight per day. These values allow the bodybuilder or athlete to build muscle mass while training.^[4]
   Note: The RDI or recommended dietary intake is the average daily intake level of a certain nutrient that’s enough to meet the nutrient requirements of nearly all healthy individuals in a specific life stage and gender group.
   Know the best time for you to take protein. Muscle protein production usually lasts between 4 to 5 hours. As a consequence, your protein intake should be at regular intervals spread evenly throughout the day (every 4 to 5 hours). This will maximise muscle protein synthesis over breakdown. Consuming protein after exercise or training is also good practice.^[5]
2. Don’t forget resistance training. Resistance training (lifting weights) creates tension and metabolic stress, resulting in increased muscle mass. Your muscles grow when muscle protein synthesis is favoured over breakdown. This can be accomplished through systematic and targeted resistance training and adequate protein intake.^[6]
3. Choose the appropriate diet regimen or dietary guideline that works best for you. There are different guidelines on how to eat healthily, increase muscle mass, and improve overall health. There’s no universal or single way to do this. You must figure out for yourself what works best for you. Below are some essential points you should consider:
   
   1. What is the right combination of macronutrients (proteins, carbohydrates, and fats) in the diet? It was customary before to base the right combination of your protein, carbohydrate, and fat intake depending on your body type: ectomorph, endomorph, and mesomorph. However, numerous research studies have found that body type eating or diet isn’t as important as it once was and may not even be necessary. Most nutrition experts and scientists do not favour body typing as the basis for your diet, especially if you want to optimise muscle building.
      
      
      
   2. The blood type diet recommends people to eat based on their ABO blood group to optimise their health and minimise their risk of developing chronic diseases. According to the blood type diet, your choice of food groups and exercise should depend on your blood type. Unfortunately, several research studies have shown no specific benefits for the blood type diet.^[7]
   3. AMDR or Acceptable Macronutrient Distribution Range. Fat, protein, and carbohydrates (macronutrients) each possess their own AMDRs. AMDRs are drawn from reliable scientific evidence demonstrating that they have a beneficial and protective effect on the health of the people in a certain region. Think of AMDR as another element to determine adequate nutrition and as a part of your set of tools similar to RDIs and EARs*. The recommended acceptable macronutrient distribution range (AMDR) in New Zealand and Australia is as follows:^[8]
      
      1. Carbohydrates = 45 – 65%, meaning 45 to 65% of a person’s daily caloric intake should come from carbohydrates.
      2. Fat = 20 – 35%
      3. Protein = 15 – 25%
      
      *RDI – Recommended Dietary Intake, EAR – Estimated Average Requirement
      
      If you’re a vegetarian, you would want to increase your protein intake to ensure you don’t develop any deficiencies. Click here to learn more about protein sources for vegans and vegetarians. Bodybuilders and athletes should also increase their protein intake based on the suggested amounts mentioned above (between 1.7 and 2.2 g per kilogram of body weight per day).
   4. Another set of dietary guidelines you can follow is the Australian Guide to Healthy Eating (2013) and Eating and Activity Guidelines for New Zealand Adults (2020). They don’t necessarily focus on optimising muscle building, but they get the basics right and put your body in a state ready for muscle protein synthesis. After getting a handle on these guidelines, you can adjust your protein intake to optimise muscle building.^[9]

The Importance of Building Muscle as You Age^[10]

You probably think that building muscle and lifting weights is only for young people, athletes, and bodybuilders. That’s not true. It’s also vital to continue to build muscle as you grow old.

Senior citizens are at a higher risk of experiencing falls. This is because sarcopenia or age-related muscle loss happens faster as you age, which can partially impair a person’s sense of balance, mobility, and strength. Maintaining muscles can decrease the risk of falls. In addition, more muscle means more fat-burning areas in the body, which helps maintain the target weight range and prevent obesity, hypertension, and diabetes mellitus type 2. Most older adults are apprehensive about starting an exercise routine. They may feel too old to be lifting weights and exercising. They may also fear getting injured. They must be reassured that exercise and weight training can be accomplished at all levels in a step-by-step approach. Furthermore, exercise and strength training certainly improve mood and cognitive brain health, uplift self-confidence, and increase independence.

What happens when you don’t consume sufficient amounts of protein?^[11]

Not consuming enough protein negatively impacts your health in different ways:

1. The immune system starts to weaken. Protein is required to build a robust immune system. It’s a component of antibodies your immune system cells make to help combat invading microorganisms.
2. You feel less full. Studies have documented that eating enough protein can suppress appetite and give you a high satiety effect. A lack of or insufficient protein in your meals will make you feel hungry with increased food cravings.
3. You become susceptible to injuries like fractures. Aside from calcium, your bones also need and use protein. Bones undergo continuous growth, remodelling, and repair, so you need enough protein to support the process. If you’re not getting sufficient amounts of protein for your vital organs, your body will obtain proteins from other areas, like your skeletal muscles. As a result, your muscles begin to shrink (atrophy) and lose their strength. Strong skeletal muscles are needed to support your bones, especially during movement. The absence of strong muscles leaves you more susceptible to injuries like fractures.
4. Malnutrition. Severe protein deficiency can result in malnutrition.
5. Damaged hair and skin. Low-protein diets can affect the health of your hair, nails, and skin, all of which are made up of proteins.

From plate to muscular physique, we have managed to follow proteins. The mechanisms by which our bodies process proteins are complex and subject to various factors. It’s evident there’s no single perfect formula for building muscle. Our bodies have unique characteristics that may benefit or slow down our progress. Be patient and find out what works best for you. Schedule a consultation with your doctor before trying out any new type of diet.