In my last article I wrote about the different dietary protein needs in general. I also expressed that although it is clear who needs baseline protein levels (current RDA), who needs more than that and who needs less, it is still not very clear how to determine the exact needs for each individual.
In order to determine exactly how much dietary protein an individual needs, IDEALLY, we need to know and be able to use ALL of the following:
- His (or her) general lifestyle
- Type and intensity of training, if any
- Age
- Gender
- Morphological body type
- Omnivore or vegetarian/vegan
- Primary, secondary, tertiary, etc. sources of dietary protein and their approximate ratios in one’s diet
- Macro nutrient (and more precisely protein) digestion efficiency (is the digestive system compromised in any way)
- Individual tolerance to different sources of protein
- Total and per-meal dietary carbohydrate ingestion levels (carbohydrates divert the use of protein from the body as a source of energy and direct its use toward body tissues recovery, rebuilding, etc., so may be less total dietary protein is needed if enough carbohydrates are eaten)
- Nitrogen balance / nitrogen retention efficiency (1 full paper, not abstract)
- Protein turnover – maintenance and growth
- Protein synthesis – maintenance and growth
- Metabolic response of the different tissues (muscles, bones) to different types of dietary protein
- Presence of metabolic syndrome issues and CVD (cardio-vascular disease), especially presence of insulin resistance and issues with other hormones, involved in the protein metabolism
Unfortunately, after some serious time spent looking for official papers I was not able to find the type of research that could help me devise an exact daily protein intake for a particular individual, based precisely on the points of inquiry I described above. At the very least, this does not seem possible without using a very sophisticated lab (I can only guess).
Nonetheless, there is enough information that can at least provide us with a good starting point, which can represent a level of dietary protein intake that, with some perhaps minor adjustments and fine-tuning, could allow us to arrive to a relatively precise (for the particular time in one’s life) daily dietary protein intake levels.
Method, based on specific needs for total daily protein intake
These are the general numbers that can provide a starting point. Examples below.
(Tip: Use the instant kilograms to pounds converter at the bottom right if you don’t know your body weight in kilograms)
- Sedentary individuals, in order to maintain zero nitrogen balance (nitrogen entering vs. nitrogen leaving the body), generally require 0.69g protein/kg/day (2), 0.66g to 0.83g/kg/day (3), and 0.8g/kg/day is the RDA (Recommended Dietary Allowance) for adults 19 and older. For simplicity sake I think it’s best to take the RDA’s number (0.8g/kg/day) as the zero nitrogen balance and work with it
- Top athletes require 1.41g/kg/day (2)
- Top male athletes require 2 x 0.8g (1.6g)/kg/day of dietary protein, and top female athletes require (0.8g + (0.8g x 0.5)) to (0.8g + (0.8g x 0.6))/kg/day. In other words, top female athletes require only 40-50 percent dietary protein in excess of the zero nitrogen balance requirements for sedentary individuals (0.8g/kg) (4)
My comments:
Not sure how to interpret “top athlete”. The Merriam-Webster dictionary defines “athlete” as “A person who is trained in or good at sports, games, or exercises that require physical skill and strength”. If I have to work with this definition and adapt it to “top athlete” it would probably be something in those lines: “A person who is trained to have superior abilities at sports, games, or exercises that require physical skill and strength”. A top athlete – for the purposes of establishing total dietary protein requirements – would be someone who trains intensely at least 5-6 times a week.
My personal suggestions for additionally modifying the baseline daily protein intake (o.8g/kg/day), based on activity level and intensity:
- Recreational athletes – moderate activity exercise – 2 to 3 times a week: add 0.2g/kg/day protein to RDA level or a total of 1g/kg/day
- Endurance athletes – long-distance running – 3 – 5 times a week: add 0.4-0.6g/kg/day protein to RDA level or a total of 1.2-1.4g/kg/day (along with higher carbohydrate intake)
- Strength athletes – heavy weights lifting 4-6 times a week: add 0.6-0.8g/kg/day protein to RDA level or a total of 1.4-1.6g/kg/day (levels of daily protein intake above these do not show clear benefits as far as increase in muscle protein synthesis, and create nutrient overload – 2)
Example:
Subject: Female top athlete
Weight: 125 lbs (57 kg – using the converter – bottom right)
(0.8×57)=45.6
45.6×0.5=22.8
45.6+22.8=68.4g protein/day
Subject: Male, sedentary lifestyle
Weight: 175 lbs (79 kg)
0.8×79=63.2g protein/day
Method, based on the total daily calories requirements
There is an alternative way to determine the dietary protein levels. It’s based on total daily calories intake:
- Dietary protein intake for sedentary adults is 12-15 percent of the total daily calorie intake
- Dietary protein intake for active adults is 15-30 percent of the total daily calories intake. This depends on the level of activity – more active will require a higher percentage of dietary protein
The rest of the calories, after total daily protein is calculated, go toward total carbohydrate and fat intake.
Example:
Total daily calories: 2000
Subject: Sedentary individual (15 percent):
2000×0.15=300 (calories from protein)
300/4=75g/day
Subject: Very active individual (30 percent):
2000×0.3=600 (calories from protein)
600/4=150g/day
More comments:
I do not personally prefer the second method – it is far more general and less specific than the first method. However, the second method is easier to put to use.
Additionally, in my personal view the first method would be more accurate if it is used to determine the dietary protein intake for persons of normal body weight (not overweight or obese). I do not see a reason why one should provide extra protein by accounting for large quantities of fat as a part of total body mass. Fat is far less metabolically active tissue than muscle tissue and it does not need much protein at all.
So, how do you tell if you are of normal body weight?
Normal body weight is when the body fat levels are 20-25 percent for women and 10-17 percent for men. Essential fat (must have to be healthy.. and alive) for women is about 10 percent and for men is about 5 percent. So, we are talking about 10-15 percent above this essential fat level for women and 5-12 percent above for men (On the ‘Net you will find sources offering different numbers as to what’s a normal body fat percentage for women and men. The numbers above are my rounded up approximations, based on my experience as a heavy individual and as an extra lean competitive athlete. Also they are based on my personal observations of populations on two continents.)
Example:
The subject is a male, sedentary, body weight=225lb (102 kg), body fat percentage=30%.
Weight of fat tissue alone: 67 lbs (30.6 kg)
Weight of fat tissue above normal weight levels (at 17 percent body fat): 29 lbs (13 kg)
225-29=196 lbs (89 kg)
If protein requirements were calculated using the initial 225 lbs body weight, the total protein would come out to 81.6g/day
If protein requirements were calculated with the correction for excess body fat, the total protein would come out to 71.2g/day.
That’s more than 10g of extra protein a day – and more than 40 Calories extra a day – that the body simply doesn’t need.
So, when calculating total daily dietary protein requirements using the first method, I’d suggest that, if necessary, you make a correction of the total body weight and equate that to ‘normal’ total body weight.
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If this article has any omissions or inaccuracies, please use the comments below to let me know. I will research and update the article accordingly.