Protein sources

Proper nutrition is essential to help athletes recover from workouts and competitions. It is widely accepted that carbohydrates are a critical fuel source during exercise and also play a major role in promoting recovery after exercise. However, the importance of protein is less understood. When people hear ‘protein’ and ‘exercise’ in the same sentence, they’re most likely to picture images of bodybuilders eating protein bars and milkshakes in order to maximize their workout. Protein is important in the athletic diet and for anyone (and not just the pros) who is hitting the gym, playing sports, going for runs or doing any other form of workout.

Technical expertise and training are the cornerstones of improving athletic performance, but good nutrition is equally crucial for success. Over the last two decades, our understanding of the important role that dietary protein plays in muscle building and recovery has grown vastly. We now know that it is not simply the quantity of protein consumed, but also the quality of that protein and when we consume it that dictates muscle health and function.



Structure of protein in peptide bond

Structure of protein in peptide bond

Proteins are made up of amino acids. Proteins are long chain of amino acids joined together by peptide bonds. The sequence of amino acids determines the proteins’ shape and therefore functions. There are thousands of different proteins in the body and they each have their own specific number of amino acids and their own sequence pattern as well.

There are 21 amino acids and there are 3 different groups of amino acids.

  • Essential amino acids– these 10 amino acids cannot be made in the body and therefore it is vital that we get them in our food.
  • Non-essential amino acids – these amino acids can be readily made in the body and so are not necessary in the diet.
  • Conditionally essential amino acids – these 6 amino acids are not always required in the diet but are essential in certain circumstances.
  • Branched chain amino acids (BCAA) – they make up 1/3 of muscle protein and are vital substrate for 2 other amino acids. Glutamine and alanine which are released in large quantities during intense aerobic exercise. They can be used directly as fuel by the muscles, particularly when muscle glycogen is depleted. Therefore very important in sports nutrition.


Protein body mass

Protein body mass

As discussed briefly in the first article of sports nutrition, the primary function of protein in the body is for growth and repair of tissues and cells. Other functions include:

  • Enzymatic Function – all enzymes are proteins needed for digestion
  • Transport Function – act as carriers for other nutrients in blood and other body fluids
  • Hormonal Function –some hormones are made up of protein e.g. insulin
  • Immune Function – antibodies which are proteins fight pathogens preventing infections
  • Buffering Function – maintain pH balance of the blood e.g. albumin
Feeling of satiety

Feeling of satiety

Proteins are also known to be the most satisfying nutrient which is an excellent addition to your diet especially for anyone who is looking to lose weight. Protein also provides a feeling of satiety and keeps you fuller for longer and help with cravings.






Protein can be broken down to produce ATP, therefore produce energy in the body. Compared to carbohydrates and fats, amino acids can only amount from 10 to 15% of total energy production. So, it does not account for too much energy in the body. The table shows us how amino acids are actually used in the body. Our body can be in 2 states: a fed state (immediately after a meal) and fasted state (2 or more hours after a meal). We do not want all our amino acids to be converted to glucose for energy, so we have to avoid the fasted state as much as possible. We want amino acids for protein synthesis and maintain our muscle mass. So, we have to make sure we are in the fed state before exercise.


Protein in the athletic diet

Protein in the athletic diet

Protein is critical for optimal athletic performance but it also known that athletes have a higher protein need than people with a sedentary lifestyle. Even with athletes the protein recommendations  is not a one size fits all because it depends on what type of sport you doing and what type of energy you expending. So, the protein recommendations exist for different categories of athletes and the variances in different protein requirements based on different factors.

The World Health Organisation (WHO) recommends 0.75g/kg body weight of protein per day for the average adult who does not exercise much.  Anyone undertaking any kind of exercise routine is definitely going to need more protein than someone who doesn’t. This is because when you exercise, you are effectively and constantly tearing and breaking muscle fibers apart, which then need to be repaired by the body, requiring protein to do so. This explains why the protein needs of athletes and regular exercisers are higher than those of average individual. Protein needs also differ depending on aims and type of sport as discussed earlier.

Protein needs for a 70kg man

Protein needs for a 70kg man



Protein sources

It’s not just the amount of protein, but also the type of protein in the diet that athletes need to take note of. Scientific research shows that simply consuming enough protein will not optimize muscle repair and synthesis because not all types of protein are equally beneficial. In order to utilize the protein we eat, the body breaks it down into basic building blocks, called amino acids. The source of the protein influences our ability to digest it properly and, therefore, the availability of these crucial building blocks.

In addition, not all proteins contain all of the amino acids the human body needs.  Biological value is a measurement of proteins in terms of how usable it is by the body or how easily it converts from being a food protein to a body protein. Protein sources are divided into 2 groups namely:

  • High Biological Value – when a protein contains the essential amino acids in a proportion similar to that required by humans. High biological value protein is provided by animal sources for instance meat, poultry fish, eggs, milk and products.
  • Low Biological Value – when the protein is missing one or more essential amino acids are scare. Low biological value protein is provided by plant sources such as legumes, pulses, grains, algae and nuts. Most plant proteins lack one or more of these essential amino acids, meaning plant sources must be combined in the diet to provide for the body’s needs. Soy and its products however are the only plant sources that provide high biological value protein.


It is advisable to consume a variety of protein sources from both plants and animal sources to get a variety of amino acids, in order to reach our protein requirement for the day. It is harder but we can get our entire protein requirement from plant sources esp. for people who are vegetarians or vegans.

two LBV foods make HBV

Two LBV foods make HBV



Eating too much protein

Eating too much protein

What should we consider if one consumes too much protein?

  • There is no advantage for performance in consuming too much protein, instead the excess protein will be broken down to glucose and stored as glycogen and fats, in turn may lead to weight gain.
  • Recommended protein intakes (up to 2g/kg/day) are not harmful in healthy individuals.
  • Once your protein needs are met additional protein will not be converted to muscle. It will be treated as excess protein by the body.
  • Eating large amounts of protein can lead to bad breath, especially if you restrict your carbohydrate intake. this could be in part because your body goes into metabolic state called ketosis which produces chemicals that give off an unpleasant fruity smell.
  • Constipation or diarrhea may occur from eating too much dairy or a high protein diet lacking fiber. increase water and fibre intake to prevent dehydration and you may wish to track your bowel movements.
  • Eating lots of red meat and full-fat dairy foods as part of a high-protein diet may lead to heart disease. This could be related to higher intakes of saturated fat and cholesterol.
  • The body flushes out the excess nitrogen with fluids and water which can leave you dehydrated even though you may not feel more thirsty than usual. increase water intake to reduce this effect.
  • Following a high-protein diet for an extended period can increase your risk of kidney damage. Eating too much protein can also affect people who already have kidney disease. Your kidneys have to work harder to get rid of the extra nitrogen and waste products of protein metabolism.


Protein is responsible for rebuilding your muscle tissues after exercise and also plays a minor role in producing energy under more extreme training conditions. The complete proteins we consume (e.g. meats, fish, dairy, eggs, etc.) are made up of the same amino acids that make up our muscles. After we consume the protein, our body breaks it down to amino acids and incorporates them into our tissues as needed. Exercise causes muscles to demand more protein than under sedentary conditions because exercise, and especially unaccustomed exercise, does structural damage to the tissues. The structural damage gives to body a reason to rebuild the tissues stronger and/or bigger so that they can handle the continuing challenges. Without protein, the body cannot perform this function and therefore you must supply it through the diet if you want to recover and build properly. Exercisers and athletes generally have a higher protein requirement than their sedentary counterparts.



  1. Protein for exercise and recovery. Phys Sportsmed.
  2. Layman, D.K., Anthony, T.G., Rasmussen, B.B., Adams, S.H., Lynch, C.J., Brinkworth, G.D., and Davis, T.A. 2015. Defining meal requirements for protein to optimize metabolic roles of amino acids. Am. J. Clin. Nutr. 101(6): 1330S–1338S.
  3. Moore, D.R., Churchward-Venne, T.A., Witard, O., Breen, L., Burd, N.A., Tipton, K.D., and Phillips, S.M. 2015. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J. Gerontol. A Biol. Sci. Med. Sci. 70(1): 57–62.




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