This document describes something called "Positive Nitrogen Balance", or PNB. PNB is a state that your body must be in if you hope to make gains in lean body mass (IE: grow muscle). It's also important to be in PNB if you are trying to recover from injury or an intense weight training session. Read through this document, and you will see some pretty complicated equations that can help you determine your exact protein needs -or- you can just use the general "rule of thumb" of making sure to simply eat one gram of protein per pound of body weight. It's easy, and it pretty much guarantees you'll be in PNB.
It is not that simple to figure out if you are in positive nitrogen balance(PNB). One thing you can say for sure, is that most bodybuilders *easily* get enough protein to be in some range of PNB.
UUN, urinary urea nitrogen can be used to estimate a persons nitrogen balance.
Step 1: UUN is measured from a 24-hour urine sample.
Step 2: Use the concentration of UUN and the 24-hour urine volume to calculate the total UUN per day using the following equation:
Total UUN = (UUN) (Urine volume) / 100
*where total UUN is in mg, urinary UUN is in mg/dl, and urine volume is in ml.
Step 3: Estimate the person's protein intake for the day.
Step 4: Calculate the person's nitrogen balance using the equation:
N balance (g/day) = protein intake/6.25 - (UUN + 4)
* where 6.25 converts protein intake to nitrogen intake (since protein is 16% nitrogen), protein intake and UUN are given in grams, and the number 4 represents grams of nitrogen excretion by routes other than urinary, plus urinary nitrogen other than in urea.
Or you can do it this way, which is *WAY* easier:
Step 1: obtain an estimate of the person's energy needs by using this following equation:
For men: BEE = 66 + 13.7(W) + 5(H) - 6.8(A)
For Women: BEE = 655 + 9.6(W) + 1.7(H) - 4.7(A)
*where W= bodyweight in kg, H= height in cm, and A= age in years.
* to get bodyweight in kg, take weight in pounds/2.2
* to get height in cm, take height in inches X 2.54 (1 inch = 2.54 cm)
* This is used to find maintenance calories
Then you need to figure out your activity factor (AF) and your injury factor (IF). For obvious reasons will we exclude the IF unless of course you think you have undergone major surgery, elective surgery, major sepsis, trauma plus steroids, or severe thermal burns.
Activity factors (AF) are as follows:
1.2 - for people confined to bed
1.3 - for ambulatory people
1.5-1.75 - for normally active people
2.0 - for extremely active people (I would choose this!)
Then take your number you got from your BEE and take it times your activity factor. That number will give you an approximation of the *maintenance* calories needed. Obviously to gain add 500 kcal's per day, to lose subtract 500 kcal's a day. (3500 kcal's = 1 pound) Whew!, that was just the first step!
Step 2: Estimate desired ratio of kcal/g of dietary nitrogen. This varies of course with person's condition. For simplicity, use 150:1 for anabolism and 200:1 for maintenance.
Step 3: Calculate the nitrogen requirement from the following equations:
N required(g) = kcal/kcal:N ratio
Step 4: using this equation, calculate the amount of protein which would contain the N required from the above equation.
Protein (g) = Nitrogen (g) X 6.25
This will give you this required protein to be in either anabolism, or maintenance depending on the ratio you choose.
For me this work out to be 183.755 grams of protein a day for anabolism at a caloric intake of 4410.12. But, I am dieting, so it needs to be refigured, but I think you get the picture. For my current weight of 224 at 6% bodyfat, ironically this works out to be about 1.7 g of protein per kg of bodyweight. Interesting!
To the person asking about protein. You gave an example of eating 100 g of P a day, but then said for example your "needs" were only 80 grams of P a day. Your wondering where it is going. If your training either anaerobically or aerobically, your probably going to be using the excess for energy needs, *BUT* that depends on caloric intake.
Jeffrey P. Krabbe
It is not that simple to figure out if you are in positive nitrogen balance(PNB). One thing you can say for sure, is that most bodybuilders *easily* get enough protein to be in some range of PNB.
UUN, urinary urea nitrogen can be used to estimate a persons nitrogen balance.
Step 1: UUN is measured from a 24-hour urine sample.
Step 2: Use the concentration of UUN and the 24-hour urine volume to calculate the total UUN per day using the following equation:
Total UUN = (UUN) (Urine volume) / 100
*where total UUN is in mg, urinary UUN is in mg/dl, and urine volume is in ml.
Step 3: Estimate the person's protein intake for the day.
Step 4: Calculate the person's nitrogen balance using the equation:
N balance (g/day) = protein intake/6.25 - (UUN + 4)
* where 6.25 converts protein intake to nitrogen intake (since protein is 16% nitrogen), protein intake and UUN are given in grams, and the number 4 represents grams of nitrogen excretion by routes other than urinary, plus urinary nitrogen other than in urea.
Or you can do it this way, which is *WAY* easier:
Step 1: obtain an estimate of the person's energy needs by using this following equation:
For men: BEE = 66 + 13.7(W) + 5(H) - 6.8(A)
For Women: BEE = 655 + 9.6(W) + 1.7(H) - 4.7(A)
*where W= bodyweight in kg, H= height in cm, and A= age in years.
* to get bodyweight in kg, take weight in pounds/2.2
* to get height in cm, take height in inches X 2.54 (1 inch = 2.54 cm)
* This is used to find maintenance calories
Then you need to figure out your activity factor (AF) and your injury factor (IF). For obvious reasons will we exclude the IF unless of course you think you have undergone major surgery, elective surgery, major sepsis, trauma plus steroids, or severe thermal burns.
Activity factors (AF) are as follows:
1.2 - for people confined to bed
1.3 - for ambulatory people
1.5-1.75 - for normally active people
2.0 - for extremely active people (I would choose this!)
Then take your number you got from your BEE and take it times your activity factor. That number will give you an approximation of the *maintenance* calories needed. Obviously to gain add 500 kcal's per day, to lose subtract 500 kcal's a day. (3500 kcal's = 1 pound) Whew!, that was just the first step!
Step 2: Estimate desired ratio of kcal/g of dietary nitrogen. This varies of course with person's condition. For simplicity, use 150:1 for anabolism and 200:1 for maintenance.
Step 3: Calculate the nitrogen requirement from the following equations:
N required(g) = kcal/kcal:N ratio
Step 4: using this equation, calculate the amount of protein which would contain the N required from the above equation.
Protein (g) = Nitrogen (g) X 6.25
This will give you this required protein to be in either anabolism, or maintenance depending on the ratio you choose.
For me this work out to be 183.755 grams of protein a day for anabolism at a caloric intake of 4410.12. But, I am dieting, so it needs to be refigured, but I think you get the picture. For my current weight of 224 at 6% bodyfat, ironically this works out to be about 1.7 g of protein per kg of bodyweight. Interesting!
To the person asking about protein. You gave an example of eating 100 g of P a day, but then said for example your "needs" were only 80 grams of P a day. Your wondering where it is going. If your training either anaerobically or aerobically, your probably going to be using the excess for energy needs, *BUT* that depends on caloric intake.
Jeffrey P. Krabbe
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