Protein Intake

Protein is vital for life, this we know. However, how much protein should one be intaking? Does that value change based on circumstance? In this article, we will break down various conditions and what the scientific literature has to say for each population’s protein requirements; we will cover non-exercising, aerobic exercising, and anaerobic exercising populations for ages above 18, so this is not a special populations article.

Normal, Non-Exercising Population

If you do not partake in any exercise, be that cardiovascular or resistance training of some sort, you fall under this category. While recommendations can change, they will not change drastically on this matter, if at all.

How much protein do I need?

Simply, consuming 0.8 g/kg of bodyweight (0.36 g/lb), as seen in the Recommended Daily Allowance (RDA) set by the nutrition division of the National Institute of Health, is sufficient for a vast majority [1]. This does not mean that consuming more will cause negative consequences in healthy populations (people with functioning kidneys, especially) within reason (+ .9 g/lb)[2].

Why?

So, a person who does not exercise typically needs less protein than a person who exercises. However, everyone needs protein – this is unavoidable. Without protein, we die – simple. Without getting too in depth, protein is essential for the creation and repair of all tissues in the body, and as our body is constantly renewing pieces of itself, a steady influx of protein gives it the necessary resources to fulfill those functions as needed [2]. The less stress (i.e. exercise, physical activity) you put on your body, the less protein it needs, but it will never need no protein as there is always turn over, even in a complete resting state.
 

Aerobic Exercising Population

If you partake in exercise that is long lasting, steady state like running, swimming, cycling, among other options, this is the section for you.

How much protein do I need?

For most aerobic, endurance, cardiovascular exercisers it is recommended to take in a bit more protein than sedentary individuals. The recommendation stands at 1.0 g/kg of bodyweight (0.45 g/lb) for light and moderate aerobic exercisers [4][5]. Those interested in partaking in vigorous aerobic exercise such as marathoners and triathletes should consume around 1.6 g/kg of bodyweight (0.72 g/lb) [4][5].

Why?

It seems that aerobic exercise does make the body increase its protein turnover by increasing muscle protein synthesis and muscle protein breakdown [3]. This is no real shock as the more strain is put on the body, the more adaptation is usually seen (in general), and as such, an increased need for protein develops. Not only does the body have to repair and maintain protein dependent tissues, but must also attenuate the increased need in capillaries, blood vessels, tissue growth, mitochondria density and more that lead to effective adaptation to stimulus (exercise) [3].
 

Anaerobic Exercising Population

If you are a lifter of any sort (powerlifting, strength training, CrossFit, bodybuilding, etc.) or into calisthenics, this is the appropriate section for you.

How much protein do I need?

This section is broken up into two parts, because of the difference between the two conditions and how many people’s performance is based on the reduction of body weight while resistance training.



 

Conditional: Caloric Surplus/Maintenance

This condition is met if you are consuming at or above your maintenance calories. In this condition, it has been suggested that a protein intake of 1.6 - 1.76 g/kg of bodyweight (0.72 g - 0.8 g/lb) is satisfactory to attenuate added need as more protein than 1.76 g/kg, in an energy surplus, will likely not be used for lean tissue growth [6][7][9].

Conditional: Caloric Deficit

This condition is met if you are in a consistent calorie deficit leading to weight loss. In this condition, the suggested intake is set around 2.3 – 3.1 g/kg of lean mass (1.05 – 1.41 g/lb) with an aim for the higher end with more severe weight loss [8].

Why?

Apart from the base need for repair similar to sedentary (non-exercise) individuals, when the body is put under moderate to heavy load, it must also adapt. This adaptation takes place by increasing size of the muscle cells, increasing neural efficiency, widening and deepening motor endplates, increasing vasculature, among a host of other changes.  In conditions with a calorie deficit, the increase in protein is needed to spare muscle catabolism as the body may choose to convert some protein for energy if not enough is around. As both of these conditions ask for resistance training of some sort, they have the highest demand on the musculature and therefor require the most protein.

SUMMARY

In summary, protein intake need increases as the stress on the body increases. Sedentary individuals have little to no stress on the body and are covered by the RDA of 0.8 g/kg of bodyweight (0.36 g/lb). Aerobic exercisers do undergo some stress and need a bit more between 1.0 – 1.6 g/kg of bodyweight (0.45 – 0.72 g/lb), with more needed with increasing duration and intensity. Finally, anaerobic exercisers need the most due to high stress situation of resistance training standing at roughly 1.76 g/kg of bodyweight  (0.8 g/lb) while in an energy/calorie surplus and 2.3 – 3.1 g/kg of lean mass (1.05 – 1.41 g/lb) if in an energy deficit.
 

Writer: Nicolas Verhoeven

Citations

[1] Nutrient Recommendations : Dietary Reference Intakes (DRI). (n.d.). Retrieved from https://ods.od.nih.gov/Health_Information/Dietary_Reference_Intakes.aspx

[2] How much protein do you need every day? - Harvard Health Blog - Harvard Health Publications. (n.d.). Retrieved from http://www.health.harvard.edu/blog/how-much-protein-do-you-need-every-day-201506188096

[3] Pikosky, M. A., Gaine, P. C., Martin, W. F., Ferrando, A. A., Wolfe, R. R., & Rodriguez, N. R. (2004). Skeletal Muscle Protein Turnover in Healthy Men and Women Following an Endurance Exercise Bout. Medicine & Science in Sports & Exercise, 36(Supplement), S323. http://jn.nutrition.org/content/136/2/379.full

[4] Tarnopolsky, M. A. (2005). Protein Requirements for the Ultra-Endurance Athlete. Medicine & Science in Sports & Exercise, 37(Supplement), S283. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/15212749


[5] Campbell, B., Kreider, R. B., Ziegenfuss, T., La Bounty, P., Roberts, M., Burke, D., … Antonio, J. (2007). International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr, 4(1), 8. Retrieved from http://www.jissn.com/content/4/1/8


[6] Tarnopolski, M. A. (1992). Evaluation of protein requirements for trained strength athletes.Journal of Applied Physiology, 73(5), 1986-1995. Retrieved from http://jap.physiology.org/content/73/5/1986

[7] Lemon, P. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of Applied Physiology, 73(2), 767-775. doi:10.1152/jappl.1992.73.2.767

 
[8] Helms, E. R., Aragon, A. A., & Fitschen, P. J. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr, 11(1), 20. Retrieved from http://www.jissn.com/content/11/1/20

[9] Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., … Phillips, S. M. (2017). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, bjsports-2017-097608. doi:10.1136/bjsports-2017-097608

 

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