Please help clear up this protein question

E

Excder

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Im taking a easy nutrition class right now at school and during a lecture i let the whole "take in 1g of protein per lb of body weight a day" statement. Thats just waht iv herd and have done a few times. My teacher was quick to send me this email.....

"Wow Michael, I cannot believe you are consuming that much protein. Did you know that your body can only handle about 250 grams of protein per day in order to get rid of the nitrogen from the breakdown of amino acids? You are really pushing it there and working your poor kidneys to death. As you might have read in the book, all of this extra protein will not give you bigger muscles. In fact, if you don't burn all of that extra energy, it will all turn to fat! You are consuming close to 1000 Calories in protein alone. I have heard the 1 gram of protein per pound of body weight before, and I'm not sure who started this, but it is incorrect, it should be one gram per kilogram of body weight."

Which is right?
 
Actually, 1 gram per kilogram of BW would be very low. That's barely above the RDA and several studies have shown that just to maintain a zero nitrogen balance people who lift weights often need way more. Recommendations often go all the way from 1.2-2.0g per kg bodyweight. I'd go for at least the highest part of that range just to be sure.

That your body can only get rid of the nitrogen from 250g of protein is based on a lot of assumptions. I've read the paper where that number comes from myself


scroll down to "Maximal Rate of Urea Synthesis and Excretion" to read about convertion of ammonia (the nitrogen) to urea.

I'm a bit unsure about the convertion rate of ammonia to urea.. I'd love to ask someone who has studied the subject, but this paper is the only paper I've found on it and the references on that part of the paper are pretty old. Even if those calculations are correct, the number depends on body weight and you should be able to eat 2g per kg BW safely.

Another thing I'm not sure of, is if the calculation take into consideration that not all amino acids are used for energy, some are put into tissues and will keep their nitrogen (so no ammonia from them). So the maximal rate of urea synthesis must be seen in connection with the amount of amino acids used for energy, not the total amino acid intake.

I've never heard of anyone healthy who has got in trouble from eating too much protein (except for explorers who ate only rabbit meat, as mentioned in the paper) but I've heard of many people who eat a lot of protein. It just doesn't add up: if protein is so dangeoraus more people would end up in the hospital for it!

Some good reads on protein requirements (remembe, as mentioned by the first article here, that nitrogen balance is not a method without weaknesses!)



I would ask the teacher for references that 1g per kilo BW is enough for strength and /or endurance athletes
 
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No problem! Another thing about the ammonia to urea thing, ammonia can also be taken out of the body via the sweat (something that often happens when we exercise for long periods of time. Amino acid metabolism goes up and the excess ammonia is secrated out along with the sweat). I don't think ammonia is a significant part of sweat at rest, but maybe if you eat so much protein that it's too much ammonia for the urea cycle to handle, the rest will be secreted out with the sweat.. Just a hypothesis.
 
Hoss said:
:::Sniff, sniff::: Karky's really grown up.
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I'm a big boy now :D

I'm surprised no supplement companies have gotten a hold of this and created a supplement that's supposed to increase the rate of urea synthesis :yelrotflmao:
 
Yeah right, people actually supplement intermediates within the urea cycle to help prevent agrinine metabolism. Increase urea synthesis?? 0hhh n033z55zz NoT mY 4rG1n1N3!!!
 
1 gram is not too low. That is above the recommended level for most people, escpecially women. Of course, endurance runners etc will puch the required level more closer to 1.6 p. kg.
 
I've read more accurately, it's 1-1.5 gram of protein per Lean Body Mass (LBM). To make life easier, I just say 1 gram of protein per lbs of body mass and most people will fit into that range. Unless you are Karky who is obese, in which case, please use the LBM range. :)

Most of the texture that I've read in bodybuilding stuff have ask to keep 1 g of protien lb of body weight whether you are in Cut or bulking phase. It's the carb manipulatiobn that will put on bulk or cut. With that said, I was and still slightly concerned about the body having to consantly filter that much protein out of the body all the time and that is why I throw in "diet" breaks days where I consume less than 1g protein / bodyweight. Like the Bible says, MODERATION.... moderation... moderation... let your body rest from bulk/cut/bulk/cut for a while once every so often.
 
plus, is this nutrition for the 'average person'? Because the average american is fat and lazy.
If you're talking about olympic athletes, or pro body builders, it all goes out the window. its like trying to compare Einstein's math prowess with a 3rd grader who just learned multiplication tables...its apples and oranges.

plus most nutritionists are still following research done in 1940-1950.
 
tic said:
I've read more accurately, it's 1-1.5 gram of protein per Lean Body Mass (LBM). To make life easier, I just say 1 gram of protein per lbs of body mass and most people will fit into that range. Unless you are Karky who is obese, in which case, please use the LBM range. :)

Most of the texture that I've read in bodybuilding stuff have ask to keep 1 g of protien lb of body weight whether you are in Cut or bulking phase. It's the carb manipulatiobn that will put on bulk or cut. With that said, I was and still slightly concerned about the body having to consantly filter that much protein out of the body all the time and that is why I throw in "diet" breaks days where I consume less than 1g protein / bodyweight. Like the Bible says, MODERATION.... moderation... moderation... let your body rest from bulk/cut/bulk/cut for a while once every so often.
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The kidney filters all day everyday, I don't understand where this belief is coming from. Proper renal function (normal tensive, no insulin problems, etc) = NO PROBLEMS WITH PROTEIN.
 
Hoss said:
Yeah right, people actually supplement intermediates within the urea cycle to help prevent agrinine metabolism. Increase urea synthesis?? 0hhh n033z55zz NoT mY 4rG1n1N3!!!
Click to expand...

People supplement intermediates within the urea cycle? seriously?
What good would that do for arginine metabolism? I've heard of supplementing kreb's cycle intermediates, but not urea cycle..
 
matt182 said:
1 gram is not too low. That is above the recommended level for most people, escpecially women. Of course, endurance runners etc will puch the required level more closer to 1.6 p. kg.
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are you sure? I know there is some discussion about this, but everything I've read has said that both endurance runners and weightlifters need quite a bit more than the recommended level (0.8g/kgBW) Usually around 1.5g just to maintain a zero nitrogen balance.
 
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