How Many Calories per Gram of Protein?

[MrX]

Excellent info Kaladryn thanks for taking the time to put that together.

Really informative. i m subscribed to this thread

 

[Kaladryn]

OK, time to get down to some nitty gritty. While most of my post above was just a simple compilation of information about Atwater's experiments, this next one will include some newer research. I will also include some more details about Atwater's data that is relevant.

First I have a question:

How many calories are in 1 gram of protein that is used for tissue synthesis (repair)?

Answer:

Zero

The fact is, unless you are breaking down protein into energy, no energy is released. You get potential energy in the form of tissue that can be metabolized if necessary, but no actual energy is released from the protein itself unless it is metabolized, aka oxidized, aka burned.

Here are some interesting numbers on food calories (kilocalories) from combustion, this does not represent digestion in the body. Fats,which are all pretty similar:

olive oil= 9.384 kcal/g
animal fat= 9.372 kcal/g
butterfat= 9.179 kcal/g

Carbs, which have more variance:

glucose= 3.692 kcal/g
lactose= 3.877 kcal/g
sucrose= 3.959 kcal/g
starch= 4.116 kcal/g

And some proteins, which have huge variance:

barley= 5.92 kcal/g
gelatin= 5.27 kcal/g
wheat gluten= 5.95 kcal/g
cows milk= 5.5 kcal/g

I'm out of time, but next post will go into energy lost in digestion, and energy lost in metabolism. Also I will try to find some more protein values, since these seem to vary the most. Finally I want to explore individual factors that may vary energy absorbed from macronutrients.

Oh and fiber, that is an important one, fiber has a LOT less calories per gram than other carbohydrates, and may reduce the energy absorption of all carbs consumed at the same time...

Here is some good reading for those interested:
**broken link removed**

 

[Ruhlfreak55]

so THIS is how humapro can claim to have almost no calories? I was wondering about this

 

[S2N]

so THIS is how humapro can claim to have almost no calories? I was wondering about this

Humapro claims a lot of stuff of which id pay them all no mind

 

[SitySlicker1]

OK, time to get down to some nitty gritty. While most of my post above was just a simple compilation of information about Atwater's experiments, this next one will include some newer research. I will also include some more details about Atwater's data that is relevant.

First I have a question:

How many calories are in 1 gram of protein that is used for tissue synthesis (repair)?

Answer:

Zero

The fact is, unless you are breaking down protein into energy, no energy is released. You get potential energy in the form of tissue that can be metabolized if necessary, but no actual energy is released from the protein itself unless it is metabolized, aka oxidized, aka burned.

Makes since...same concept as glycogen being store in the liver and muscle (potential energy).

Interesting stuff, K. Thanks.

 

[homonunculus]

Kaladryn,

It might be helpful to explain that you're essentially just copying and pasting from wikipedia, here.

Also, the energy derived from protein IN THE BODY is really pretty simple, as it's a matter of:

-Digestibility.

-Subtracting the heat of combustion of urea (which you haven't specifically touched upon), which what's giving values in the 5+kcal / g for each of the proteins you're mentioned vs. values closer to 4kcal/g, which we all know and love.

-Variability in the energy content of the various amino acids d/t structure and thus variability in different proteins as well as energy cost of hydrolysis of the peptide bonds.

I think you're trying to make this thread instructive, but the amount of mystery you're building into it is probably just creating confusion, I suspect, for the lay reader...

-S

 

[Kaladryn]

Kaladryn,

It might be helpful to explain that you're essentially just copying and pasting from wikipedia, here.

Also, the energy derived from protein IN THE BODY is really pretty simple, as it's a matter of:

-Digestibility.

-Subtracting the heat of combustion of urea (which you haven't specifically touched upon), which what's giving values in the 5+kcal / g for each of the proteins you're mentioned vs. values closer to 4kcal/g, which we all know and love.

-Variability in the energy content of the various amino acids d/t structure and thus variability in different proteins as well as energy cost of hydrolysis of the peptide bonds.

I think you're trying to make this thread instructive, but the amount of mystery you're building into it is probably just creating confusion, I suspect, for the lay reader...

-S

Most of the quotes in the first post is from the wiki on the Atwater system. However a lot of the subsequent information is from the paper I linked above, **broken link removed**. With some additional information from further studies on the Atwater system. Ultimately everything I have posted- except for that first quote from a biochem class I had years ago- is from google.

That being said, I'm trying to do more than just copy and paste quotes from Wikipedia. I want people to understand just how much "quasi-science" is involved in these calorie determinations, and how much mystery remains.

I'm afraid you have missed the entire point of this thread. What you say is "simple" about the energy derived in the body is exactly my point, it is not simple, a few very loose studies have made us think it is, when in fact it is not:

1. There are huge variances digestibility, not only between different macronutrients themselves, but also how those macronutrients are mixed. On top of that, things like isolated proteins have never been studied, hydrolyzed proteins, digestive enzymes, etc, have all never been studied and I would bet some of these have much higher rates of digestibility.

2. As for uncombusted nitrogen in the urine, I did briefly mention that, however this is not the only place energy is lost in protein metabolism. There is an ADDITIONAL 20% loss in energy from gluconeogenesis. This is why the one person who posted 3.2 calories per gram is correct. But all this assumes that protein is fully metabolized. 4 calories/gram ASSUMES the person is in nitrogen balance, perfect nitrogen balance is a theoretical state that does not exist.

I agree with you that this is a lot to do about nothing to some people. But for others, for example people who weigh all their foods and calculate all their calories carefully, the amount of imprecision built into the "calorie system" we rely on is useful to know, and ultimately we are talking about unknowns here, the science is vague.

Basically I'm trying to get people to think outside the box a bit more on nutrition, because I think there is a lot more to know than what the standard layman dogma tells us, and more, even, than the more advanced science tells us.

 

[jayl19]

what about protein in carb foods is it exactly the same as protein in meats, ie same calories, same amino acids etc

 

[homonunculus]

Most of the quotes in the first post is from the wiki on the Atwater system. However a lot of the subsequent information is from the paper I linked above, **broken link removed**. With some additional information from further studies on the Atwater system. Ultimately everything I have posted- except for that first quote from a biochem class I had years ago- is from google.

That being said, I'm trying to do more than just copy and paste quotes from Wikipedia. I want people to understand just how much "quasi-science" is involved in these calorie determinations, and how much mystery remains.

I'm afraid you have missed the entire point of this thread. What you say is "simple" about the energy derived in the body is exactly my point, it is not simple, a few very loose studies have made us think it is, when in fact it is not:

1. There are huge variances digestibility, not only between different macronutrients themselves, but also how those macronutrients are mixed. On top of that, things like isolated proteins have never been studied, hydrolyzed proteins, digestive enzymes, etc, have all never been studied and I would bet some of these have much higher rates of digestibility.

2. As for uncombusted nitrogen in the urine, I did briefly mention that, however this is not the only place energy is lost in protein metabolism. There is an ADDITIONAL 20% loss in energy from gluconeogenesis. This is why the one person who posted 3.2 calories per gram is correct. But all this assumes that protein is fully metabolized. 4 calories/gram ASSUMES the person is in nitrogen balance, perfect nitrogen balance is a theoretical state that does not exist.

I agree with you that this is a lot to do about nothing to some people. But for others, for example people who weigh all their foods and calculate all their calories carefully, the amount of imprecision built into the "calorie system" we rely on is useful to know, and ultimately we are talking about unknowns here, the science is vague.

Basically I'm trying to get people to think outside the box a bit more on nutrition, because I think there is a lot more to know than what the standard layman dogma tells us, and more, even, than the more advanced science tells us.

Hey, carry right on, man. I just hope you're serving your greater purpose here of creating understanding.

-S

 

[bloodshed]

Id like to bump this. Great thread

 

[destin]

Had to read it a couple times! lol

 

[Simpllyhuge]

Marking thread for later reading

 

[Lilleo187]

Guys making a big deal over -1 or +1 calories lol.

 

[Kaladryn]

Guys making a big deal over -1 or +1 calories lol.

When you are talking about 4 or 5 calories per gram protein, the difference is 125%, or when carbs are closer to 3 calories per gram instead of 4 due to fiber content, it can make a big difference in overall calories.

I know you are just trolling, good thread resurrection.

 

[hilly2008]

Most of the quotes in the first post is from the wiki on the Atwater system. However a lot of the subsequent information is from the paper I linked above, Is a calorie a calorie?1,2,3,4. With some additional information from further studies on the Atwater system. Ultimately everything I have posted- except for that first quote from a biochem class I had years ago- is from google.



That being said, I'm trying to do more than just copy and paste quotes from Wikipedia. I want people to understand just how much "quasi-science" is involved in these calorie determinations, and how much mystery remains.



I'm afraid you have missed the entire point of this thread. What you say is "simple" about the energy derived in the body is exactly my point, it is not simple, a few very loose studies have made us think it is, when in fact it is not:



1. There are huge variances digestibility, not only between different macronutrients themselves, but also how those macronutrients are mixed. On top of that, things like isolated proteins have never been studied, hydrolyzed proteins, digestive enzymes, etc, have all never been studied and I would bet some of these have much higher rates of digestibility.



2. As for uncombusted nitrogen in the urine, I did briefly mention that, however this is not the only place energy is lost in protein metabolism. There is an ADDITIONAL 20% loss in energy from gluconeogenesis. This is why the one person who posted 3.2 calories per gram is correct. But all this assumes that protein is fully metabolized. 4 calories/gram ASSUMES the person is in nitrogen balance, perfect nitrogen balance is a theoretical state that does not exist.



I agree with you that this is a lot to do about nothing to some people. But for others, for example people who weigh all their foods and calculate all their calories carefully, the amount of imprecision built into the "calorie system" we rely on is useful to know, and ultimately we are talking about unknowns here, the science is vague.



Basically I'm trying to get people to think outside the box a bit more on nutrition, because I think there is a lot more to know than what the standard layman dogma tells us, and more, even, than the more advanced science tells us.

Good points.

However to your last bit. It’s not helping or opening up any knowledge really as it’s as you say ‘unknown’

So we can’t utilise this information to improve what we are currently doing so.

It’s really just going to cause more confusion n in accuracy if people tried to consider these things.

Unless I’m missing something ?


Sent from my iPhone using Tapatalk

 

[hilly2008]

@kaladryn - what a great old thread I hadn’t seen.

Do u no of any more data that would or has caused u to change your approach in the last 6 years.

I imagine we may know a little more About this area ?

I’m going to go do some reading


Sent from my iPhone using Tapatalk

 

[Kaladryn]

I guess the main point of this thread is that the formula that we use for carbs and protein being exactly 4 calories per gram is somewhat misleading and if you swap out foods based on this math, you will get varied results.

 

[Zapzap]

Interesting

 

[Kaladryn]

It is also useful to note that this is really old, IIFYM was all the rage during this period, that was probably the main motivation putting this info together, you can't really just switch out proteins and carbs and expect the calories to be exactly the same.

Also, the majority of this info is from a very interesting study I posted a link to above called "Is a calorie a calorie?" Someone suggested I lifted this info from a wiki, which I wouldn't think there was anything wrong with, but in fact, I am paraphrasing this study which is probably a source for many wikis. I don't know why this origin is important to some people, stupid.

 

[OutToLunch]

Guys making a big deal over -1 or +1 calories lol.

Why revive draconian thread lol