Indeed, there’s a net yield, but it’s quite variable, depending on what’s going on. The changing electrical potentials are what happens, whether it’s in a calorimeter or in our bodies. Burning something is exothermic just as ATP to ADP is.
If we want to know how much ATP - we’d need to know what percentage or ratio of a body’s energy production is going to go into that, put the body in a whole-room calorimeter, and measure the energy, then convert it to ATP. There’s nothing remotely as accurate as that. Calories/7300 = moles of ATP.
PaulL
(You've tried everything else; why not try bacon?)
#22
That’s where my problem lies. It’s not, as I understand it, anyway, the heat that powers the cell, it’s electrical potential. So the heat is the by-product, not the cause of the metabolic activity. I’m just wondering how our picture of what goes on might change, if we were to alter our paradigm.
Bikman talks about this, mentioning, for example, the increased net yield of ATP per unit oxygen that muscle cells are able to achieve on a ketogenic diet. I wonder how that affects the equation, and whether energy-balance is the best way to look at things. Perhaps ATP/ADP balance is a more effective aid to understanding? I wish I knew enough biochemistry to answer this question, and I look forward to seeing more commentary from researchers as they delve into this. It’s pretty clear that the standard way of looking at things isn’t helping us.
Another thing Bikman asserts is that the best way to evaluate our energy-balance thinking would be to run weight-gain studies, not weight-loss studies. His point is that fat cells will not grow in the absence of insulin, so a study in which we tried to put weight on people would be a better way to compare the effects of high- and low-insulin diets. Studies of trying to take weight off produce too many confounders, he says, to make those data useful in any way. It’s certainly an interesting point.
Okay, but what is the actual question, there? The physics of what is happening isn’t a mystery, even while the body is of course an enormously complicated deal, as are the functions of life.
Indeed, ‘heat’ isn’t the whole deal, by a long shot. ATP powers almost everything in a cell. Transport proteins that make nerve cells light up, motor proteins that make muscles contract, ribosomes that construct those proteins in the first place, etc.
Still, things are indeed exothermic all the way along - we’re starting with organic molecules - fats, proteins, carbs - and electrons from them progressively move through the electron transport chain, ending up at oxygen. It’s a stepping-down of energy states, where energy is given up each time. This is cellular respiration, and its goal is to make ATP (which is ‘captured energy’ for the body, like a battery).
To “look at ATP” is tough - we recycle all the ATP in our body every 70 seconds or so. One of the best proxies for ATP use is just seeing how much oxygen the organism is using, on the front end. While not perfect nor totally exact, because of some things that are variable, I don’t think there is anything else remotely close, there. Additionally, the results can be refined toward even higher accuracy by measurements on the back end.
The ATP/ADP ratio in healthy cells is usually 10:1 or more. And it will change - if we sprint for ten seconds it declines somewhat, and takes a while to rebuild (we can’t immediately sprint mutiple times without performance dropping off), and it also takes a while to replace our creatine phosphate. But the overall turnover remains huge. For example, a muscle cell in action is using about ten million ATP molecules per second, and that muscle cell recycles all its ATP in less than a minute. ATP/ADP balance - it does tell us some things, but it’s also very transient.
Bikman - more ATP per unit of oxygen if keto - certainly. In the mitochondria of cells, it depends on what is being metabolized. All other things being equal, per unit of oxygen, ATP production should be 15% lower using carbs, versus using fats. It stands to reason that somebody on a ketogenic diet would be using a higher ratio of fat to carbs.
How to figure it? Again - put the person in a whole-room calorimeter. The really good, modern ones measure one’s exhaled gases, along with a whole bunch of other stuff. As above, the person’s usage of oxygen is recorded. Then, the ‘respiratory quotient’ (“RQ”) is measured - the ratio between carbon dioxide exhaled to oxygen consumed. An RQ of 1 shows that it’s all carbs that are being used. If all fats, it’s 0.71.
Measure how much nitrogen is excreted, to control for protein usage, then interpolate to figure the mix of carbs and fats.
I think that is what people do. Usually, “losing fat” is the deal. Okay, so, is the body making net withdrawls from its energy stores or not? In no way does this rule out the CIM - it will apply to varying degrees.
Totally agreed, and I would love to see it. Aside from any disagreements about confounding things, I think (hope) that everybody can agree that fat loss - like ~225 grams or a half pound of fat per day, is possible. And whatever mechanistic terms we may favor in describing the process, there, it’s a very real and pertinent question as to how that relates to weight gain.
If we’re talking about insulin levels, then to me it’s obvious that they make an enormous difference, or at least a very substantial one. Low-insulin (or at least it was lower, in my case) - I’d eat far in excess of my energy expenditure, but would be ‘wasting’ some of that energy as heat (and perhaps in other ways as well; not sure). Now that I’m older and in a higher-insulin state, that doesn’t apply as much.
At some point, regardless of diet, the body’s ability to store excess as fat will be exceeded.
Ok, so I went to test whether I could get a zero on my ketone meter. I did a body weight workout one day (1 hour if body split into two parts; 1.5 hours if whole body; can’t remember which one I did). I ate meat that I weighed out for lunch (my first meal, about 3 hours after exercise) and ate 100g carbs of rice noodles.
That day was like I never ate carbs, I think because the carbs went into my muscles. I did not get a zero on my ketone meter.
I then ate the exact same meal the next day for lunch, but no exercise in the morning. I did not get zero on my ketone meter.
However, I felt terrible. I was hungry, tired, etc.
EXACT same food. One day, the carbs went into my muscles, then next day there was nowhere to go.
Bob’s current theory: The body is incredibly complex. Corollary 1: anything that simplifies this to a single statement or treats the body like a machine is wrong.
This idea that the only thing that matters is calories is wrong. It’s wrong. It’s wrong. It’s wrong.
And putting people in calorimeters is absolutely useless, because we DON’T LIVE IN CALORIMETERS. We live in the real world. We have to eat. We have to figure out what affects us and what doesn’t.
And the VERY SAME FOOD can affect us in different ways.
Well Bob, that’s just silly. That is not the argument. Paul mentioned ATP, and that takes us directly to energy. We don’t have to say “calories,” at all, but energy is what the body gets from ATP, and energy is what the body is going after if it uses up some of its store of fat.
I did edit the above, in case it sounded too dismissive. But look all through this thread, is there anybody actually saying that calories are the only thing that matters?
Figuring stuff out is why we would measure things in a calorimeter. And what better method of measuring things would you propose?
Well Bob, that’s just silly. That is not the argument. Paul mentioned ATP, and that takes us directly to energy. We don’t have to say “calories,” at all, but energy is what the body gets from ATP, and energy is what the body is going after if it uses up some of its store of fat.