If you ask any athlete, most of them will tell you that protein is needed for muscle growth and repair. But what they often don’t know is that it makes up most tissues and cells in the body and is essential for the majority of the processes, such as hormone and enzyme production, nutrient and oxygen transfer and various metabolic reactions ^[1,2].

It is one of the three macronutrients and contains 4kcal of energy per gram, making up around 10-15% of the bodies daily energy intake [3]. Most protein in the body is found in the muscles, but it’s also contained in all cells and tissues like the skin, organs and blood.

Amino acids are often considered to be the building blocks of proteins. There are 20 different amino acids found in plant and animal foods, which together form chains to make up proteins. Eight of these amino acids are said to be essential as the body cannot produce them itself and so they must be consumed in the diet, while the other 12 are non-essential ^[2].

 

Foods that contain all of the essential amino acids are called complete proteins and generally come from animal sources such as meat, poultry, fish and dairy ^[2]. Most plants sources are generally lacking in one or more of the essential amino acids and are therefore are considered incomplete.

This does not, however, mean that plant sources cannot provide the body with all of the essential amino acids. Consuming a variety of different plant sources will ensure athletes are consuming all of the essential amino acids.

How much protein an athlete needs is based on age, sex and body weight and so will vary from athlete to athlete.

Although there are no set recommendations for nutritional requirements of youth athletes, its estimated that they will need slightly more protein in their diet than less active children of the same age.

Non-athletic children aged between 13-18 years will need between 0.85g - 1g of protein per kg of body weight, compared to 1.2g -1.4g of protein per kg of body weight for youth athletes ^[4,5].

This allows the body to rebuild, repair and grow in response to the sport they do, as well as ensuring they meet their bodies demand for natural growth and development.

 

Body Weight	Daily Protein Requirement
	Non- Athlete	Athlete
45 kg	38 - 45g	54 - 63g
50 kg	42 - 50g	60 - 70g
55 kg	47 - 55g	66 -77g
60 kg	51 - 60g	72 - 84g
65 kg	55 - 65g	78 - 91g
75 kg	64 - 75g	90 - 105g

The timing of protein intake has been found to be just as important as the amount of protein consumed, with recommendations suggesting improved recovery and muscle gain when some protein is eaten before exercise, as well as shortly after exercise ^[2].

Whilst it's common for both athletes and those in the general population to backload their protein and consume most of it with their evening meal, recommendations suggest that protein intake should be spread evenly across all meals and snacks ^[5].

Image Credit: National Cancer Institute

Protein is found in a huge variety of foods with the best and most complete sources often coming from animal products such as meat, poultry, eggs and dairy.

However, there are various different plant foods which are high in protein, and when eaten in combination, can provide the body with all of the essential amino acids. Below we look at the protein content of some common foods sources based on average serving sizes ^[6].

Food	Protein Content
Chicken (one breast ~125g)	30g
Steak (sirloin fillet ~225g)	49g
Salmon (one fillet ~94g)	24g
Milk (one glass ~300ml)	10.8g
Eggs (one medium)	6.4g
Quorn (one fillet)	6.7g
Baked Beans (1/2 tin)	9.4g
Tofu (one serving ~70g)	8.8g
Quinoa (80g portion)	3.5g
Soya Milk (one glass ~300ml)	10.2g
Peanut butter (1tbsp ~15g)	3.8g

One common misconception is that eating protein will give you big muscles and make you stronger.

While protein is essential to both muscle growth and repair, the process of building muscle is much more complex than simply eating more protein. In fact, excess protein is simply excreted from the body in the urine or will be stored as fat ^[5].

Similarly, many athletes believe they need to consume a protein supplement in order to meet their daily needs. However, as shown in the table above, protein requirements can easily be reached through eating a healthy and balanced diet and a food first approach is always recommended.

Take a look at our other articles for more information on the other essential macronutrients: covering fat and carbohydrates.

 

1. Cotugna, N., Vickery, C. and McBee, S. (2005). Sports Nutrition for Young Athletes. The Journal of School Nursing, 21(6), pp.323-328. 
2. Lanham-New, S. (2011). Sport and exercise nutrition. Oxford: Wiley-Blackwell.
3. British Nutrition Foundation. (2018). Protein. [online] Available at: https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/protein.html?limitstart=0 [Accessed 19 Sep. 2019].
4. Boisseau, N., Vermorel, M., Rance, M., Duché, P. and Patureau-Mirand, P. (2007). Protein requirements in male adolescent soccer players. European Journal of Applied Physiology, 100(1), pp.27-33.
5. Bean, A. (2013). Anita Bean's Sports Nutrition for Young Athletes. London: Bloomsbury Publishing.
6. Roe, M., Pinchen, H., Church, S. and Finglas, P. (2015). McCance and Widdowson's The Composition of Foods Seventh Summary Edition and updated Composition of Foods Integrated Dataset. Nutrition Bulletin, 40(1), pp.36-39.