Protein is definitely the most popular of the three macronutrients (protein, carbs, and fat), and it gets a lot of the attention in the fitness industry. The amount of attention that protein gets is reasonable when you look at the slew of benefits it can provide for health and fitness. These benefits include: increased muscle retention and growth, reduced hunger, increased thermic effect of food, and many more. I will be going into greater detail on the benefits of protein in a later post, but for now it is sufficient to know that there are a lot. But the question then becomes; how much do you actually need to consume to get these benefits?
The amount that an individual needs is largely dependent on their body size, lifestyle, and age. I will go into a variety of lifestyle situations and age considerations later in this post, but first I will outline why body weight is the underlying factor for any recommendation.
Body weight can vary quite drastically from person to person. This variance can be due to height, gender, bone structure, fat mass accumulation, and muscular development. When stating protein recommendations, the target will often be phrased as “X grams of protein per pound/kilogram of body weight” or abbreviated as, “Xg/kg” or, “Xg/lb”. The rationale for the use of body weight scaling systems is simply due to the additional needs of larger people. If we compare two divergent situations this concept becomes quite obvious. Imagine one person who is 130 lbs and another person who is 250 lbs. The larger person is going to need far more resources, such as protein, to repair and maintain the extra 120 lbs they are carrying around. Just as a 25 floor building costs more to maintain than a 15 floor building, larger people require more protein.
Before delving into any of the following numerical recommendations, I would like to clarify a few points about protein consumption. If you have either kidney disease, liver malfunction, or other ailments that may be worsened by moderate-high protein intakes, consult with a doctor before making dietary modifications. I would also like to explain that the g/kg or g/lb that I will be recommending are based on high quality protein sources (meaning they digest and absorb well), which are mainly found in animal products. If you are consuming a vegan diet you may need to be more conscious of the amino acids in certain foods, and you may want to consume slightly above the protein levels I am discussing below.
If you are a fairly sedentary individual that doesn’t partake in any form of moderate to high intensity exercise, your protein requirements will be quite low, given your low levels of muscle breakdown. You will still need some dietary protein to maintain healthy bodily functions, but this amount is probably only around 1.2g/kg(Humanyun et al, 2007) of protein per day. If these amounts are not met, your body may be forced to choose between muscle repair or maintenance of its more vital structures. Your body prioritizes the maintenance of organs and other structures over the repair of muscle. Therefore, if protein is under consumed for long periods of time, muscles can deteriorate and shrink in size. Increasing consumption up to 1.8g/kg(Bray et al, 2012) will likely further increase lean mass, which can be beneficial for a variety of health and lifestyle outcomes.
If you are regularly active and partake in some form of sport or training program, your protein recommendations will be higher than a sedentary individual. The regular breakdown of muscle tissue will require higher amounts of protein to rebuild. For this type of activity, general recommendations range from 1.4g/kg up to about 2.2g/kg(1g/lb) (Morton et al, 2018) of protein per day. In this range, results and recovery are fairly similar. Some studies show that the upper end of this range may have slight benefits for body composition, performance, and recovery. If you place high value on these outcomes it may be best to consume around 2.2g/kg. Current research shows that this level of protein consumption does not have any negative health impacts, unless you have one of the conditions previously mentioned (Antonio et al, 2016).
If your main goal is to gain as much muscle as possible, you may want to consume slightly more protein than a normal active individual. Aiming for between 1.6g/kg and 2.5g/kg (Campbell et al 2018) will probably optimize the muscle you will gain. Much like the range in the previous paragraph, it may be beneficial to aim for the higher end of this range. As long as it doesn’t crowd out other important nutrients, from carbs and fats, there is no downside to aiming this high, and there may be potential benefits.
If you are currently prioritizing fat loss you should be using a similar range to the ones outlined in the muscle gain paragraph. Intakes around or even above 2.5g/kg may be useful in this stage to preserve muscles and reduce hunger. If maximal muscle retention is not a priority, you may choose to use the active individual recommendations.
Now that I have covered the major lifestyle factors, I will briefly discuss some considerations that come with age. Sarcopenia is a disorder that results in loss of muscle, and reduced physical function. This condition gains prevalence as one ages and is especially common in women. Rates of sarcopenia rise significantly over the age of 50 (in the US 40% of men and 60% of women)(Janssen et al, 2002) and increases the chance of premature death and drastically reduces quality of life. Those past couple sentences were pretty depressing so I’ll give you the good news; Sarcopenia is preventable and reversible. This disorder can be prevented through the use of proper resistance training and high protein intakes. The issue is that protein is absorbed less effectively as we age, and we often eat less food in general. The result of this is significantly less digested protein. Not good. I would recommend a minimum protein intake of 1.2g/kg(Rafii et al, 2015) and higher intakes are even better. Consuming between 1.6g/kg(Mitchell et al, 2017) and 2.2g/kg can be incredibly helpful for individuals who are lacking the strength and muscle to perform daily functions.
I have set out many recommendations in this post and have often portrayed a relatively higher protein intake as better. While I think this is true in a hypothetical sense, we should always consider what is realistic. If you are regularly resistance training, but you find that it is incredibly difficult to eat 2.2g/kg of protein a day, just start with 1.4g/kg. The differences in results will be very small, and a plan that you can do constantly and enjoy is far better than the one you hate. Find what works best for your lifestyle and preferences, then stick with it. Higher protein consumptions may be a struggle at first, but over time it will become second nature. The trick is to find protein sources that you enjoy and are easy to fit in your lifestyle.
Connor Crouse, PN1, PTS
Head Nutrition Coach
KPCC Coaching
Citations
Humayun, M. A., Elango, R., Ball, R. O., & Pencharz, P. B. (2007). Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique. The American journal of clinical nutrition, 86(4), 995-1002.
Bray, G. A., Smith, S. R., de Jonge, L., Xie, H., Rood, J., Martin, C. K., ... & Redman, L. M. (2012). Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. Jama, 307(1), 47-55.
Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., ... & Phillips, S. M. (2018). 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, 52(6), 376-384.
Antonio, J., Ellerbroek, A., Silver, T., Vargas, L., & Peacock, C. (2016). The effects of a high protein diet on indices of health and body composition–a crossover trial in resistance-trained men. Journal of the International Society of Sports Nutrition, 13(1), 1-7.
Campbell, B. I., Aguilar, D., Conlin, L., Vargas, A., Schoenfeld, B. J., Corson, A., ... & Couvillion, K. (2018). Effects of high versus low protein intake on body composition and maximal strength in aspiring female physique athletes engaging in an 8-week resistance training program. International journal of sport nutrition and exercise metabolism, 28(6), 580-585.
Janssen, I., Heymsfield, S. B., & Ross, R. (2002). Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability. Journal of the American Geriatrics Society, 50(5), 889-896.
Rafii, M., Chapman, K., Elango, R., Campbell, W. W., Ball, R. O., Pencharz, P. B., & Courtney-Martin, G. (2015). Dietary protein requirement of men> 65 years old determined by the indicator amino acid oxidation technique is higher than the current estimated average requirement. The Journal of nutrition, 146(4), 681-687.
Mitchell, C. J., Milan, A. M., Mitchell, S. M., Zeng, N., Ramzan, F., Sharma, P., ... & Cameron-Smith, D. (2017). The effects of dietary protein intake on appendicular lean mass and muscle function in elderly men: a 10-wk randomized controlled trial. The American journal of clinical nutrition, 106(6), 1375-1383.