In reference to this chapter/post link text from Dr. James E. Carlson's book "Genocide, how your doctors dietary ignorance will kill you!", I would like to ask a few questions regarding this "Calories" measurement please.
If a calorie is a way of measuring Combustion (how much heat is given off - the definition for it) then where exactly do we "burn" food inside our bodies?
If this place exists, is this "burning" process really so huge and even close to be used as a reputable measurement of any/potential energy inside a human body? Don't we UTILIZE free fatty acids for energy instead of "burning" stuff?
What about all the enzymes, hormones, metabolic pathways etc, why is that not part of this Calories calculation ?
Has there ever been a single study in any country in any language where it was proofed anything in the lines of "Food with 150 Calories will provide more usable energy inside the human body than something with 100 Calories". I am not talking about measuring combustion in a closed container in a lab, I am talking about actual clinical studies on a human body ?
Should we not maybe search for a better term to measure energy inside the human body than Calories ?
asked byLowcarbJC (65)
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on June 01, 2011
at 04:45 PM
This is a great question, simply stated and can provide a ton of insight. I'll try my best here, but on my shelf I have three 1000+ page books on thermodynamics, so this will be quite a simplified introduction. If anyone wants more details, let me know and I can try to do a better write up with pictures and everything.
First, lets start with the definition of a calorie. A calorie is a unit of energy which is defined as the amount of energy required to heat 1 gram of water 1 degree C. A Calorie (capital C) is 1000 calories and is a "food calorie". So it's just a bigger unit or energy. From here on I'll be talking about "Calories" even if I forget to capitalize it...
When someone says "how many calories are in something", that's really short hand for how many calories are released during the combustion reaction:
Food + Oxygen -> Carbon Dioxide + Water
or as a chemist would write it:
Food + O2 -> CO2 + H2O
Bascially there's an intinsic energy in everything, but that's HUGE and immeasureable (easily), so we always talk in "changes in energy". So in the reaction above, the heat released is:
H = [ E(CO2) + E(H2O) ] - [ E(Food) + E(O2) ]
Where E(x) is the intrinsic energy in x. But we can't measure that, we just measure the heat released, H.
Ok, so what then do we use that to tell us how much energy is in food? Well, as long as we have a convention, then we're good. So our convention is that the "end products" are CO2 + H2O and we measure everything releative to that.
In the end, all food is "burnt" (oxidized) in the mitochondria and will eventually turn in to CO2 (what you breath out) and H2O (also what you breath out or pee) or it's excreted (poop). So when you eat food the reaction is really this:
Food + O2 -> CO2 + H2O + Poop
The CO2 and H2O are the byproducts of combustion (or your metabolism). We can write this in short hand like this:
Food -> Energy + Poop
Which thermodynamically is written as
[ E(Energy) + E(Poop) ] - [ E(Food) ]
Which looks very suspicically like
Energy out - Energy in (Chemists write it backward from nutritionists)
And that's where everything goes wrong, people think that you can eaisly control both energy out and energy in. But if you look at the original equation this came from
Food -> Energy + Poop
You can see that the only thing you really have control on is energy in (Food), the rest is controlled in your metabolism. Ok, so now on to your questions:
1 - We burn food in the mitochondria. The by products are just like a traditional combustion reaction Food + O2 -> CO2 + H2O
2 - We can introconvert things, but all that matters is the starting and ending point. For example:
Food -> Fatty Acids Fatty Acids + O2 -> CO2 + H2O
So the first reaction is
E(Fatty Acids) - E(Food)
and the second reacation is
[ E(CO2) + E(H2O) ] - [ E(Fatty Acids) + E(O2) ]
Add those two reactions together, you'll see that the E(Fatty Acids) on both sides cancel out and you're left with
[ E(CO2) + E(H2O) ] - [ E(Food) + E(O2) ]
3 - Again, the only thing that matters is the starting and ending point. This would be best with a picture, but I don't have one right now. When you go from Food -> Energy, you need some "extra" energy to get started (go up a hill), then after the reaction gets started, you get that energy back plus more (go down a hill). Think of being at an elevation of 1000' with a rock (that's the E(Food)), you push that rock up a hill to 1100' (put some energy into the system), at the top of the hill you let the rock roll down the other side to 500' (that's the E(Energy) you get back. So you ended up getting some energy out of the system, the rock fell from 1000' to 500', but it didn't go until you pushed it up over the hill at 1100'. (That's your metabolic pathway). Now enzymes are special chemicals that help you out by lowering that hump you have to go over. An enzyme will lower the hump you have to go over, say to 1001' (now it's really easy for the reaction to happen). But it has NO effect over the end products or energy. Here's a good picture of that on wikipedia. The black line is the original reaction, the red line is what the enzyme does. But in the end, you started at the X,Y height and ended up at Z. What they call Ea is the activation energy, energy to get the reaction started. What they call DeltaG is what I called H, how much energy is released in the reaction. As you go along the X-axis from X,Y to Z that's the "reaction path" or in the body that would be the "metabolic pathyway".
4 - You don't need a study. But the type of food matters. When you eat food, it either goes to energy, poop, or stored in your fat cells. How that's partitioned depends on so many variables and we can't really control them, that's all controled by our bodies.
5 - No, energy is energy is energy, it's all interconvertible. In the world of physics and chemistry we can move energy around where we want. In our bodies, it's up to our horomones (for signalling) and enzymes (for lowering the hump), and lots of other stuff. All we can really control is what we put in as fuel.
Ok, that's enough for now, but I can add more if you have more questions. It's hard to do this without going into lots of thermodynamics, that you probably don't care about.
on May 31, 2011
at 09:58 PM
We measure the calories in food because that's what we know how to do - not because it makes sense. At the cellular level, it's how much ATP you can get out of something that matters. IIRC, its 34 ATP from 1 molecule of glucose and as much as 108 ATP from one fatty acid molecule (fatty acids vary quite a bit). The bulk of amino acids from protein are used to make more proteins such as enzymes or muscle tissue and are therefore not available as fuel. Some amino acids can be used directly in the krebs cycle to create ATP and some can be converted to glucose via gluconeogenesis (but energy is lost in the conversion). Fatty acids are also used as structural components of cell membranes (and other things) and so not all dietary fat is available as "fuel". And I don't know whether what the bacteria in your intestines are eating can be counted as caloric intake by you...
Sorry, excessive rambling... But I think Dr. Carlson is on to something.
on June 01, 2011
at 04:24 PM
check out Robb Wolf podcast Episode 77 around the 28-30 minute mark. A nerd's dream of an explanation on a question similar to yours. Enjoy!
on February 26, 2012
at 10:38 AM
thanks ppl, i really found it useful!!
on June 07, 2011
at 12:52 PM
Great article - corresponds with what Dr. Carlson said :
on June 01, 2011
at 09:51 PM
Thanks for all the answers. I am going through each one of them in as much detail as possible the next few days. Appreciated.