Conservation of energy in living organisms

[Zeuzzz]

Been reading into this and while the conservation of energy in physics and chemistry seems pretty much beyond repute it seems bit more complex when it comes to biology.

Sorry but the quote is from Rupert Sheldrake^WP

http://runesoup.com/2012/06/what-you...-can-kill-you/

Quote:

Let’s ask Dr Sheldrake. This is him recounting the results of some experiments where you seal humans inside a chamber and measure all the energy (food and light) they absorb as well as all the energy they expel (you know how that works). It should be a zero sum, yeah?

In the late 1970s, Paul Webb reinvestigated human energy balances in his laboratory in Ohio, with surprising results. The figures simply did not add up, especially when subjects were over-eating or under-eating… Webb also found puzzling discrepancies in other previous studies. He concluded, ‘The more careful the study, the more clearly there is evidence of energy not accounted for.’

In Webb’s own experiments, he took a careful tally of the food eaten over a three-week period, changes in body weight, heat and other forms of energy output, as well as measuring rates of oxygen consumption and carbon dioxide production. He found that more energy was being used than he could explain. He did not question the law of conservation of energy, but instead suggested that there was an as yet unrecognised and unmeasured kind of energy, which he called x. Taking all the studies together, x was on average 27 per cent of the total metabolic expenditure; in other words, more than a quarter of the energy was unaccounted for.

However, a modern-day vitalist could assert that there is a vital force at work in living organisms, over and above the standard forms of energy known to physics. A yogi could speak in terms of prana, or an acupuncturist in terms of chi.

Do the available data rule out any kind of energy not yet known to physics? Is present-day nutrition science so precise that it can explain every detail of energetic activity in animals and people? The answer is ‘no’.

Careful, precise research might ultimately support the orthodox dogma, but at present it is an assumption, not a fact.

Although most people do not realise it, there is a shocking possibility that living organisms draw upon forms of energy over and above those recognised by standard physics and chemistry.[....]

By treating the laws of conservation and matter and energy as testable hypotheses rather than revealed truths, physiology and nutrition science would become more scientific, not less so. [...]

Does this argument have any type of weight to it? Are there more recent studies into energy generation/conservation in living organisms?

I expect the seeming generation of excess output energy in living organisms is in fact due to people missing some other mechanisms by which they take energy in, but can not think what they may be. Not too up to par on all potential energy intake and outtake mechanisms animals have. He's essentially supporting a type of biological energy creation as opposed to the usually assumed energy generation/conversion.

[geni]

Humans are an extremely poor choice of test subject. Trying to track a human's energy intake and expenditure over more than a minute or so would end up with massive sources of error and would certianly be impossible to do precisely with 1970s tech. Bacteria would be a more reasonable approach.

No cell process that has been studied suggests any non acounted for sources of energy.

[godless dave]

Originally Posted by Zeuzzz

Does this argument have any type of weight to it?

No.

Originally Posted by Zeuzzz

I expect the seeming generation of excess output energy in living organisms ....

Has anyone observed an excess output?

[Zeuzzz]

Originally Posted by geni

No cell process that has been studied suggests any non acounted for sources of energy.

I suspected this, so are there no anomalies at a cellular level documented at all?

I presume in animals that metabolism is the rate of energy use, thus is one of the main factor that gives variation between organisms. Hibernation would have to slow it down drastically.

The more I think about (n)factors that could effect energy input or output for large organisms the more impossible meaningful conclusions from input and output energy become.

[Zeuzzz]

Originally Posted by godless dave

Has anyone observed an excess output?

Yes, threads started here by me.

In terms of excess energy output as far as im aware they are pretty much all anecdotal. Inedia^WP is when people stop eating yet survive for longer than they should, which has not been replicated in controlled conditions.

I'm also wondering what extra energy input mechanisms there could be for people instead of just food energy. Would be nice to build up an input / output list of the main ones, but that's probably a near impossible task.

[shuttlt]

Normally Sheldrake's results stand up to scrutiny. Perhaps we should give him the benefit of the doubt?

[Zeuzzz]

I think his theories about psychic dogs anticipating owners return home via supernatural means was a fairly large enough nail in his credibility coffin.

[Perpetual Student]

Élan vital.

[Hellbound]

Originally Posted by Perpetual Student

Élan vital.

Orgone.

[Zeuzzz]

He has brought up some interesting questions and perspectives on things over the years however, despite some of his more outlandish claims.

Probably best to forget the source of the quote and focus on the content for a more productive thread.

Cryonics and cryopreservation may be an interesting area to conduct research into this by measuring the temperature difference between the environment and the animal on reanimation.

[TjW]

"Pay no attention to that man behind the curtain!"

[Zeuzzz]

Just re-read the chapter that provoked this thread and nearly every reference is from pre 1980 research, or at least modern publications that are merely citing old research.

There are a couple of more modern references I should probably add here.

Quote:

In 2010, a team from the Indian Defence Institute of Physiology and Allied Sciences (DIPAS) investigated an eighty-three-year-old yogi called Prahlad Jani, who lived in the temple town of Anbaji in Gujarat. His devotees claimed that he had not eaten for seventy years. In the DIPAS study, he was kept for two weeks in a hospital under continuous observation and filmed on CCTV cameras. He had several baths and gargled, but the medical team confirmed that he ate and drank nothing, and passed no urine or faeces. A previous medical investigation in 2003 had given similar results.

The director of DIPAS said, ‘If a person starts fasting, there will be some changes in his metabolism but in his case we did not find any.’ This is an important point, because surviving a two-week fast is in itself not particularly impressive. Most people could do that, but there would be very noticeable physiological changes while they did so.

For reference: Defence Institute of Physiology and Allied Sciences^WP

On a slightly unrelated note, it would be interesting to know the dietary energy input of people like Wim Hoff (aka The Iceman) to compare this to the expected heat loss expected from running half marathon on ice with no clothes on in Lapland. I expect the rise in metabolism from the high cardiovascular activity may be the main factor here, he would have to have his food intake measured and be weighed before and after to be sure.

[Dinwar]

Originally Posted by Zeuzzz

Been reading into this and while the conservation of energy in physics and chemistry seems pretty much beyond repute it seems bit more complex when it comes to biology.

Sorry but the quote is from Rupert Sheldrake^WP

http://runesoup.com/2012/06/what-you...-can-kill-you/



Does this argument have any type of weight to it? Are there more recent studies into energy generation/conservation in living organisms?

I expect the seeming generation of excess output energy in living organisms is in fact due to people missing some other mechanisms by which they take energy in, but can not think what they may be. Not too up to par on all potential energy intake and outtake mechanisms animals have. He's essentially supporting a type of biological energy creation as opposed to the usually assumed energy generation/conversion.

No, this argument has no weight. We know that ecosystems lose energy, and can demonstrate that at every level, from the individual cells in an organism (and even the individual chemical reactions) to ecosystems as a whole. Defication is proof of it. The loss of biomass as you go up trophic levels is proof of it. The necessity for some sort of photo- or chemosynthesis at the base of every food web is proof of it. The K/Pg extinction event is spectacular proof of it.

What is far, far more likely is that this person doesn't understand ecology. Detritovores create a feedback loop that keeps energy and mass in the biosphere far longer than you'd expect if you ignore them (how long is the subject of a great deal of controversy). They're easy to miss, and very, very easy to underestimate.

Quote:

I presume in animals that metabolism is the rate of energy use, thus is one of the main factor that gives variation between organisms.

Tell me, Zeuzzz, have you studied much biology? And I mean really studied it, not just read fringe books on the subject? Do you know what you are arguing against?

[Dancing David]

Originally Posted by Zeuzzz

Been reading into this and while the conservation of energy in physics and chemistry seems pretty much beyond repute it seems bit more complex when it comes to biology.

Sorry but the quote is from Rupert Sheldrake^WP

http://runesoup.com/2012/06/what-you...-can-kill-you/



Does this argument have any type of weight to it? Are there more recent studies into energy generation/conservation in living organisms?

I expect the seeming generation of excess output energy in living organisms is in fact due to people missing some other mechanisms by which they take energy in, but can not think what they may be. Not too up to par on all potential energy intake and outtake mechanisms animals have. He's essentially supporting a type of biological energy creation as opposed to the usually assumed energy generation/conversion.

How about Webb's alleged research rather than a second hand quote?

[Dancing David]

Originally Posted by Zeuzzz

I suspected this, so are there no anomalies at a cellular level documented at all?

I presume in animals that metabolism is the rate of energy use, thus is one of the main factor that gives variation between organisms. Hibernation would have to slow it down drastically.

The more I think about (n)factors that could effect energy input or output for large organisms the more impossible meaningful conclusions from input and output energy become.

No, that is silly.

Energy out put is simple, you use a box to measure heat output and other means to measure energy in.

What is so hard about that?

[Dancing David]

Originally Posted by Zeuzzz

Yes, threads started here by me.

In terms of excess energy output as far as im aware they are pretty much all anecdotal. Inedia^WP is when people stop eating yet survive for longer than they should, which has not been replicated in controlled conditions.

I'm also wondering what extra energy input mechanisms there could be for people instead of just food energy. Would be nice to build up an input / output list of the main ones, but that's probably a near impossible task.

how about some actual data that shows the food and body fat is not sufficient?

[Dinwar]

Originally Posted by Dancing David

how about some actual data that shows the food and body fat is not sufficient?

That's the other complication: establishing initial conditions is extremely hard to do, since in biology there really isn't an initial condition. Even conception doesn't work, because the egg and sperm cells have mitochondria and ATP and other structures that complicate things (and there's the food coming from the mother's body).

It is EXTREMELY easy to create a poorly-thought-out experiment in biology, one that leaves out various factors. It's far easier to pretend that those confounding factors don't exist, and that you've made some great discovery.

Originally Posted by Zeuzzz

Probably best to forget the source of the quote and focus on the content for a more productive thread.

If you have to say that, your source is garbage and there's probably not enough worth discussing to warrant a thread.

[Zeuzzz]

Originally Posted by Dancing David

How about Webb's alleged research rather than a second hand quote?

Just done some digging into the exact papers cited for these claims. These seem to be them:

Energy balance in man measured by direct and indirect calorimetry. 1991

Quote:

In six 24-hr measurements of energy balance, direct and indirect calorimetry agreed within +/-3%, which is probably the range of experimental error. But in seven other 24-hr periods there was disagreement in the range of 8 to 23%, and these were usually days when the subjects ate much less than they spent metabolically. Our direct calorimeter is an insulated, water cooled suit. Continous measurements of O2 consumption and CO2 production provided data on metabolic expenditure (M) by indirect calorimetry. The 24-hr values for M matched the energy losses within +/-60 kcal (+/-3% of M) in four men who rested all day and lay down to sleep at night. Similar agreement was seen in one of the four who worked on a treadmill for 4 hr and stayed busy all day. but in another energy losses were 342 kcal greater than M (10% of M). When the experiments gave values for M minus the losses greater than +/-60 kcal, this is called "unmeasured energy". In further experiments, two subjects stayed awake for 24 hr, and their unmeasured energies were 279 and 393 kcal. The same two men, eating sparingly, also worked for 24 hr so as to double their resting metabolic expenditures; the unmeasured energies were even larger, 380 and 958 kcal. When they repeated the 24 hr of mild work, but ate nearly as much as they spent metabolically, one man was near energy balance, while the other showed an unmeasured energy of -363 kcal. Little heat storage was evident in these experiments; therefore, heat balance was present and energy balance should have been present. In the group of 13 experiments, it appeared that the greater the food deficit, the larger was the unmeasured energy (excess of metabolic expenditure over loss of energy).

The measurement of energy expenditure 1991

Quote:

This is a brief account of the development of energy expenditure measurements, from speculations by early philosophers on the nature of the "innate fire," through the beginnings of quantitative animal calorimetry and to the combined material and energy balances of Rubner and of Atwater and Benedict, which established the science of nutritional energy. The equivalence of oxidation rate and heat loss led to the simplification of indirect calorimetry, followed by the era of studies of basal metabolic rate. Current practices are reviewed for measuring energy expenditure by indirect calorimetry (respiration chambers, ventilated hoods, doubly labeled water) and direct calorimetry (rooms, suits). Because problems remain in the exact account of energy balance during weight change, growth, pregnancy and exercise, perhaps it may be time to combine once again carbon balance with energy balance, using modern methods.

The following may be related as they are the same year by the same author, (Sheldrakes citations are awfully hard to follow as he only gives the author and the date without the title of the paper)

Sedentary daily expenditure: a base for estimating individual energy requirements

Heat regulation during exercise with controlled cooling

I think his argument (Sheldrakes) is essentially a calorimetry based argument about the anthropocentric definition of food energy; that external molecular heat energy calibration instead of subjective physiological calorimetric energy calibration may be misleading. I may be over analyzing the point he is trying to make, however.

[godless dave]

I don't see where he accounted for fat stores.

[Zeuzzz]

Originally Posted by Dancing David

No, that is silly.

Energy out put is simple, you use a box to measure heat output and other means to measure energy in.

What is so hard about that?

Heat output being the only energy output then?

[Dinwar]

Originally Posted by Zeuzzz

(Sheldrakes citations are awfully hard to follow as he only gives the author and the date without the title of the paper)

That is standard for in-text citations. You'd cite (Dinwar, 2013), then have the reference in the References section. If there are multiple papers by that author in the same year, you'd go (Dinwar, 2013a) for the first, and (Dinwar, 2013b) for the second. I've seen them go as high as d (maps, many of which were published at the same time).

Quote:

In six 24-hr measurements of energy balance, direct and indirect calorimetry agreed within +/-3%, which is probably the range of experimental error. But in seven other 24-hr periods there was disagreement in the range of 8 to 23%, and these were usually days when the subjects ate much less than they spent metabolically.

So they were days when the subjects burned fat reserves. This is a mystery to no one who knows biology--that's how fat reserves WORK.

[Zeuzzz]

My metabolism must be off the charts then, I stay the same weight no matter how much I eat, or how lazy I am, I've tried to push 75kg but it simply doesn't happen (+-1kg).

The biological non SI unit definition for food energy (calorie) seems to me to be a rather crude measure of energy, in terms of the more easily definable conservation of energy/mass used typically in non biological physics. The wiki on this [Energy balance (biology)^WP] seems extremely void of references.

[godless dave]

Originally Posted by Zeuzzz

My metabolism must be off the charts then, I stay the same weight no matter how much I eat, or how lazy I am, I've tried to push 75kg but it simply doesn't happen (+-0.5kg).

I used to be the same way!

When I was around 27 I finally started gaining weight. And gaining, and gaining, and gaining. Because I'd never had to worry about limiting my food intake before then, I developed a lot of bad habits.

[Dinwar]

Originally Posted by Zeuzzz

My metabolism must be off the charts then, I stay the same weight no matter how much I eat, or how lazy I am, I've tried to push 75kg but it simply doesn't happen (+-1kg).

I'm that way. However, I also know enough about physiology to know that that's not the whole story. Defication, urination, sweating, oil and aromatic compound production, hair, nail, and skin growth, and many other factors come into play. All of those are ways where nutrients and energy leave the body. Again, this is extremely hard to quantify in any meaningful way.

Quote:

The biological non SI unit definition for food energy (calorie) seems to me to be a rather crude measure of energy, in terms of the more easily definable conservation of energy/mass used typically in non biological physics.

And the cladistics definition of "character" is useless when discussing literary criticism. What's your point?

If you want to talk conservationof mass/energy, look at mass. Biomass always goes down as you go up trophic levels, and each trophic level has about 10% the biomass of the one below it. That's a 10% efficiency. 10%<100%. Thus, we can safely conclude that no, biology is not creating new energy out of nothing.

Quote:

The wiki on this [Energy balance (biology)WP] seems extremely void of references.

Seems like every conversation you and I have I say this: Read actual scientific publications. For this, I'd start with a textbook. I'm sure you can get one relatively cheap at any university town, particularly if you wait until after Bio 101 or 110 is out.

[phunk]

Originally Posted by Zeuzzz

My metabolism must be off the charts then, I stay the same weight no matter how much I eat, or how lazy I am, I've tried to push 75kg but it simply doesn't happen (+-1kg).

The biological non SI unit definition for food energy (calorie) seems to me to be a rather crude measure of energy, in terms of the more easily definable conservation of energy/mass used typically in non biological physics. The wiki on this [Energy balance (biology)^WP] seems extremely void of references.

The food calorie is just the metric kilocalorie. It's a perfectly reasonable and well defined measure of energy. The trouble isn't in the units, it's in the measurement. Biology is messy.

[Dinwar]

Originally Posted by phunk

The food calorie is just the metric kilocalorie. It's a perfectly reasonable and well defined measure of energy. The trouble isn't in the units, it's in the measurement. Biology is messy.

Well, somewhat.

When you read the callory count on a box of cookies you're not actually reading how much energy your body will take from them. The way they measure callories is to put them in a bomb calrimeter. There's an outer hull, a layer of water, an inner hull where the food goes, then electrodes that run a charge through the food to burn it (it's usually fairly fast, thus the "bomb" in the name). A callorie is the amount of energy required to rise the temperature of 1 ml of water 1 degree C, so you just need to measure the starting temperature, ending temperature, and volume of water to get the callories in the food. I'm sure they do some sort of adjustments, but that's the basics of the procedure.

The issue is, the body won't converat all that material into energy. So bioavailable energy isn't going to be as high.

The issue isn't the definition of the terms, but rather how we measure them.

Callories in vs. callories out is still the best we've got in terms of weight loss and the like, but if you want precise measurements of metabolic activity you have to measure mass of food in, mass of everything out, and body mass at minimum. This is extremely hard to do with any precision.

[Zeuzzz]

Originally Posted by Dinwar

you have to measure mass of food in, mass of everything out, and body mass at minimum. This is extremely hard to do with any precision.

Mass is a very easily defined and measurable property. Why would it be so hard?

[Dinwar]

Originally Posted by Zeuzzz

Mass is a very easily defined and measurable property. Why would it be so hard?

Really? You're honestly asking that?

Sheesh.....

Okay, let's start easy. You are an arobic organism. That means you need to breath. How are you going to measure the mass out from each breath? It's a lot more than "breath in oxygen, breath out carbon dioxide"--you actually exhale a hoast of chemicals, including mucus, water, pharamones, bits of lunch stuck in your teeth (why do you think bad breath exists?), etc. And you inhale spores, dust, dander, viruses, bacteria, and the like along with the air you take in. How are you going to measure that in an organism?

Ignore the fact that we can define mass. It's irrelevant to the question. How are you going to actually measure how much air a person takes in and exhales each time they breath in and out? Remember, we've got to do this for days. And this is not an insignificant issue--arobic metabolism works basically by combustion (on an EXTREMELY small scale), and CO2 is a primary byproduct of that process.

Then you have the constant shedding of dead skin cells. How are you going to measure that? Every time you take your shirt off, brush against a wall, every time you take a step you drop cells.

How about hair falling out? It's replaced once every 3 to 7 years or so, after all--even non-balding people shed at a certain rate.

Defication? How are you going to measure it? Dry weight is fine, but by definition removes the water--a significant nutrient. Wet weight? How are you going to obtain that? Americans poop in toilets, and as anyone who's watched Austen Powers can tell you poop is water-soluble to a certain degree. You want to use a bedpan? That's fine--how are you going to capture the volatile compounds?

How about urine? Urine splashes. Gotta account for ALL the mass.

My point is, there are a lot of places where it simply isn't practical to assess mass in a living organism. And humans are easy--you can actually talk to them and have the test subjects help you. Try measuring the mass in and out of a butterfly in the wild. Or a croc. Or an elephant. Or a field mouse.

This isn't a physics question about mass, where the fact that we can measure it to ten significant figures is relevant. It's a basic quesiton of whether our measuring capabilities allow for such a degree of certainty, and they simply don't for large organisms. There are innumerable factors leading to false data, and the only way to account for them all would be to put the creature on a space station for a generation or two.

[Dancing David]

Originally Posted by Zeuzzz

Heat output being the only energy output then?

If they do something, what will happen?

Hmmm?

It will produce heat.

[Zeuzzz]

That explains why physics professors avoid the biology professors, I guess.

Seems that biological mass is so variable and transient it can be treated more like a process than a property.

Materialism for organisms is pretty much dead, in my eyes; the material seems to be perpetuated only transiently by the immaterial processes of biology. They all obey the conservation of energy though, as far as I can tell.

[Dancing David]

Originally Posted by Zeuzzz

Just done some digging into the exact papers cited for these claims. These seem to be them:

Energy balance in man measured by direct and indirect calorimetry. 1991

Oh wow, lets measure them for just 24 hours and if they have less food intake lets pretend its 'unmeasured energy', but lets not give initial body mass, and subsequent body mass, and intake. Which would give what, body mass lost?

[Dinwar]

Originally Posted by Zeuzzz

Seems that biological mass is so variable and transient it can be treated more like a process than a property.

Are you familiar with the concept of an open system?

Quote:

Materialism for organisms is pretty much dead, in my eyes

Given that you can't demonstrate any support for your OPs when pressed, I'm not overly concerned. Add to that the fact that you don't seem to understand how biology works in any depth, and I'm even less concerned. If you agreed with me, THEN I'd be concerned.

Quote:

They all obey the conservation of energy though, as far as I can tell.

[Perpetual Student]

Have we accounted for the metabolism of ektoplazm, which is known to require phlogistoniclly negative energy?

[Libra]

The brain will consume 20% of the total energy, wants to run on glucose, something it does not store for use in times of need. Fatty acids are broken down for energy and the Ketone bodies are consumed by the brain when glucose is in short supply. The brain can also use lactate during excercise, something the subjects were doing in the study.

Were all these considered in determining the "x" factor of the supposed missing enery ?

[Libra]

Originally Posted by Dinwar

No, this argument has no weight. . . . Defication is proof of it.

I find it ironic that the proof of the argument's flaw is consistent with my initial thought on the subject, even though the intent of my initial thought on the subject were comfortably far removed from providing any counter argument . . .

[dlorde]

Originally Posted by Zeuzzz

There are a couple of more modern references I should probably add here.

Quote:

In 2010, a team from the Indian Defence Institute of Physiology and Allied Sciences (DIPAS) investigated an eighty-three-year-old yogi called Prahlad Jani, who lived in the temple town of Anbaji in Gujarat. His devotees claimed that he had not eaten for seventy years. In the DIPAS study, he was kept for two weeks in a hospital under continuous observation and filmed on CCTV cameras. He had several baths and gargled, but the medical team confirmed that he ate and drank nothing, and passed no urine or faeces. A previous medical investigation in 2003 had given similar results.

The director of DIPAS said, ‘If a person starts fasting, there will be some changes in his metabolism but in his case we did not find any.’ This is an important point, because surviving a two-week fast is in itself not particularly impressive. Most people could do that, but there would be very noticeable physiological changes while they did so.For reference: Defence Institute of Physiology and Allied Sciences^WP

I saw a documentary investigating 'breatharianism' (or Inedia, the supposed ability to survive on air alone), where they followed up this Indian research, interviewed hospital staff, and viewed some of the CCTV. It turned out not to be as well-controlled as claimed, with opportunities for unobserved drinking (e.g. of bathwater), and suspicion that food had been smuggled in by sympathetic staff or aides.

The woman breatharian, who was the main subject of the documentary, was tested in a more controlled environment and the test had to be stopped on medical advice after a couple of days, as she became dangerously dehydrated.

[The Don]

Originally Posted by Zeuzzz

My metabolism must be off the charts then, I stay the same weight no matter how much I eat, or how lazy I am, I've tried to push 75kg but it simply doesn't happen (+-1kg).

The biological non SI unit definition for food energy (calorie) seems to me to be a rather crude measure of energy, in terms of the more easily definable conservation of energy/mass used typically in non biological physics. The wiki on this [Energy balance (biology)^WP] seems extremely void of references.

The same is more or less true for me, except that I know that it isn't. 15 years ago I was 20 kg heavier than I am now and nowhere near as active. Mrs Don and I went on Weightwatchers and lost the weight and have kept it off since.

These days it feels like I eat as much as I like and don't seem to put any weight on but then again I can't each as much as I used to (or as much as my fat friends) and I tend not to choose high fat and high sugar foods as much as I used to (or as much as my fat friends).

I'm also a compulsive fiddler and cannot sit still (Mrs Don on the other hand can be almost entirely immobile for hours), I'm always shuffling or jiggling. This probably burns a lot of energy in a not obvious way.

My idea or sedentary has also changed considerably. Since I moved out to the country into a bigger house with a garden, I do a lot more chores that also burn energy. I may feel that I haven't exercised because I haven't gone out for a 5 mile run but then again I've spent an hour mowing the lawn or 20 minutes chopping firewood.

As I understand it (an I'm happy to be proved wrong) there are a small number of people with anomalous metabolisms but for most of us we burn pretty much the same amount (per KG of muscle or fat).

A very thin colleague complains that he cannot put on weight. I've seen what he eats in a day and I've heard how little he drinks. I'm pretty sure that if he ate 3 jumbo sausage rolls instead of a low fat hummus wrap and drank 6 pints of Guinness each night instead of the occasional glass of wine we could have the weight on in no time

[phunk]

Originally Posted by Dinwar

Well, somewhat.

When you read the callory count on a box of cookies you're not actually reading how much energy your body will take from them. The way they measure callories is to put them in a bomb calrimeter. There's an outer hull, a layer of water, an inner hull where the food goes, then electrodes that run a charge through the food to burn it (it's usually fairly fast, thus the "bomb" in the name). A callorie is the amount of energy required to rise the temperature of 1 ml of water 1 degree C, so you just need to measure the starting temperature, ending temperature, and volume of water to get the callories in the food. I'm sure they do some sort of adjustments, but that's the basics of the procedure.

The issue is, the body won't converat all that material into energy. So bioavailable energy isn't going to be as high.

The issue isn't the definition of the terms, but rather how we measure them.

Callories in vs. callories out is still the best we've got in terms of weight loss and the like, but if you want precise measurements of metabolic activity you have to measure mass of food in, mass of everything out, and body mass at minimum. This is extremely hard to do with any precision.

Not getting the 'somewhat' part, it seems you completely agree with what I said.

[Zeuzzz]

Since heat energy is the main way we loose energy why don't people in climates way below body temperature have to eat loads more than people in more temperate regions?

I'm trying to apply all sorts of physics to humans about kinetic energy and heat energy and they just end up with silly answers when you think about them practically.

Ke = 0.5mv² and E = SHm∆T simply don't work very well for such complex geometry and such a complex holistic system as a person.

Would be nice to see how energy is conserved in a Tibetan monk who meditates and raises parts of his skin temperature by 10C or his core body temperature by 2-3C in a few minutes with no extra food and no physical exertion.

I would say it's a cognitive mastery of metabolism via biofeedback but I don't think the relationship between metabolism and core body temperature is that linear.

[Dinwar]

Originally Posted by Zeuzzz

Since heat energy is the main way we loose energy

BZZT!!!! Wrong!

Quote:

I'm trying to apply all sorts of physics to humans about kinetic energy and heat energy and they just end up with silly answers when you think about them practically.

That would be because you're making an incorrect assumption, and aren't addressing the measurement issues I raised.

Quote:

Would be nice to see how energy is conserved in a Tibetan monk who meditates and raises parts of his skin temperature by 10C or his core body temperature by 2-3C in a few minutes with no extra food and no physical exertion.

If this is true the answer is simple: they have enough reserve energy stored in their body from their regular diet to do this. Humans aren't cars--we evolved mechanisms for storing energy and nutrients for lean times.