Good Calories, Bad Calories

Having been raised in the American Midwest, I grew up believing that the four basic food groups were sugar, salt, starch, and grease.

Now that I live on the west coast, I find that whatever food was last week's Great Menace is this week's Dietary Miracle, and vice-versa.

Pass the pork rinds.
 
stevea said:
Now as for "a calorie is a calorie" - I think this needs more discussion. The equivalence of energy is certainly unquestionable, but how much biological energy can be derived from a source is a different question. Food calories are (as far as I know) measured in a conventional calorimeter which measures the energy developed as the food is completely burned. By that measure a lump of coal would contain a lot of energy, but it would certainly not provide much useful biological energy when consumed orally.
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The original research on caloric intake of food used calorimetry via burn like you describe. This was later adjusted for "in body" numbers, the easy standard is 4kcal/g proteins and carbohydrates and 9kcal/g fats. This is explained very well in McArdle's Exercise Physiology textbook.

A Calorie (capital C means kcal = 1.000 calories with lower case c) is basically a calorie, ie two people on a diet of equally many calories will lose equal amounts of fat. However appetite control IS the key to weight loss because the best diet is one you can actually maintain with relative comfort in a real life situation. Thats why low-fat doesn't work despite good research on its efficacy.

But its of course a lot deeper since carbohydrates have no known benefits that make them "essential" while fats are used to make various hormones and have a role preventing excessive blood clotting and controlling the inflammatory response (to name a few). Further, a high-fat diet is associated with higher testosterone levels (which means a 10% increase in metabolic rate, increased muscle mass and increased strength as well as other non-slimming effects) while high-carbohydrate diets decrease serum testosterone.

And then the plot thickens again! The preferred fuel source during shortage (like low calorie diets) is the one that is eaten most. So a high-carbohydrate low-fat diet will decrease efficiency of using the extra fat and increase the catabolic rate of muscle meaning decreased muscle mass (remember also the decrease in testosterone which also lowers muscle mass) so you get a much smaller "spending pool" meaning you have now entered a vicious cycle. A high-fat diet will then mean a greater efficiency of fat spending and less muscle loss.
 
Muppet said:
The original research on caloric intake of food used calorimetry via burn like you describe. This was later adjusted for "in body" numbers, the easy standard is 4kcal/g proteins and carbohydrates and 9kcal/g fats. This is explained very well in McArdle's Exercise Physiology textbook.

[...I hope we all know what a kcal or a joule is...]

But its of course a lot deeper since carbohydrates have no known benefits that make them "essential" while fats are used to make various hormones and have a role preventing excessive blood clotting and controlling the inflammatory response (to name a few). Further, a high-fat diet is associated with higher testosterone levels (which means a 10% increase in metabolic rate, increased muscle mass and increased strength as well as other non-slimming effects) while high-carbohydrate diets decrease serum testosterone.

And then the plot thickens again! The preferred fuel source during shortage (like low calorie diets) is the one that is eaten most. So a high-carbohydrate low-fat diet will decrease efficiency of using the extra fat and increase the catabolic rate of muscle meaning decreased muscle mass (remember also the decrease in testosterone which also lowers muscle mass) so you get a much smaller "spending pool" meaning you have now entered a vicious cycle. A high-fat diet will then mean a greater efficiency of fat spending and less muscle loss.
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The efficiency of caloric extraction is certainly an issue. When eating additional fibre the extraction of calories from fat is reportedly reduced for example. You don't retain all the calories you eat. Also the very issue of useful caloric extraction from food is questioned .... This full article
http://www.nutritionj.com/content/3/1/9
describes a common thermodynamic misunderstanding (and there are others wrt entropy in the organism). It (somewhat misleadingly I think) indicates that thermogenesis from protein metabolism is higher than from carb. The misleading part is that thermogenic energy is not a complete loss. Still we'e expect a *local* entropy decrease in human energy storage as fat or glycogen.

I don't quite believe that McAdle or anyone else can perform any simple measure of "in body" energy use. The problem is this; the carbon in carbohydrate, and fats, and the amino acids of protein both have functional use in the body. So some carbon and aminos consumed end up in the human body. In the case of protein the amount is very substantial. In an adult the body's immune system tears down a shocking 200-400gm of body protein per day. It is estimated that about 3/4th of the aminos of the protein are re-used to replace lost protein, but there is still a non-energy dietary requirement for 50-100gm of protein per day which has nothing to do with energy. Even for carbos it's on the order of a percent or so. So you cannot simply measure the energy-input as various macro-nutrients (carbos, protein, fat) and presume these are used for energy.

Then we have the issue you mention, where the diet itself has an impact on the the metabolism, *but* the increased metabolism is easily measured as heat or other energy release in a "body study". My bigger concern is that human studies do not assay the humans before and after to see how much macronutrient is incorporated in the organism.

My only direct reading of human food:calorie studies goes back to an early 1900s scientisict at one of the eastern US universities ... he constructed a room-size calorimeter and placed (sequentiallty) team athletes in the calorimeter for several days at a time. He could easily measure the food-in calories with a bomb-calorimeter. He also measured the energy output in waste matter with a bomb calorimeter(eww). The room-calorimeter gave him a direct measure of net energy out (as heat to the environment). As a cross check he also measured CO2 out, but this is an indirect and weak measure. Anyway he got good closure on the numbers (~2%), but frankly I'm not very impressed. He did not measure the stored energy difference between the athlete bodies in vs out. If they each displace 1/4 ounce of water with 1/4 ounce of body protein or fat then energy balance would not be valid.

I can't see how you can construct such a study to avoid this problem without placing humans in a bomb calorimeter and incinerating them. Perhaps I'm missing something in the experimental design.

SteveA
 
Since a "calorie" is a measure of heat, and ice cream is frozen, then it stands to reason that you can eat as much ice cream as you want without gaining weight as long as you don't let the ice cream thaw out.

It's twoo! It's twoo!

:runaway
 
A Calorie is a Calorie at the base level (in terms of energy units). I agree, that not all calories, so to speak, are not created equal, and this is why.

The body has to take the food we eat, and break it down into its caloric essence (so to speak). To do this with some food, such as simple carbohydrates (bread, potato, pasta, rice) it is quite simple, and is done quite readily. However, for other foods, such as protein, and fibre, the process is much more involved, takes longer, and takes more biological processes. As a result, we (A) lose more of the harder to breakdown foods through transit through and out of the GI Tract, and (B) get less of an insulin spike, and hence less fat storage, through eating these harder to breakdown foods.

So I guess, depending on where the Calories come from (the food type) the calories can be rapidly available for that burst of energy, but also that energy crash, or it can be available on a more linear (over time) basis, enhancing satiety, and decreasing fat storage (through a more even insulin response).

TAM:)
 
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I agree T.A.M - the energy (not heat Fnord) equivalence is easy to evaluate, but this doesn't mean that humans can extract all the energy for biological use. Muppet's McArdle reference should address this, but I'd like to see the journal papers of gov't study that addresses this issue.

FWIW - the gibbs free energy of glucose is 686kcal/mol or 3.8 Cal/gram. Dextrose and starch are just mostly alpha 1-4 linked glucose with a slightly higher energy density. The alpha 1-4 link and the occasional 1-6 link contain a tiny bit of extra energy. The G-G bond removes a water molecule in a 'condensation' reaction and this reduces the ultimate starch mass per glucose by 10%. So starch approaches 4.2 Cal/gram. The figures are just slightly higher for

Fat ... stearic is a common free saturated fatty acid of human fat w/ an energy density of 9.64cal/gm and the glycerol that binds three of these into a triacylglyceride (fat) lowers the energy density by about 6%, so perhaps 9.1Cal/gm.

The calculation for protein is far more complex and I won't consider it here.

My point is ... it sure *seems* that the food calorie figures match the chemical free energy figures rather than some experimentally derived measure of how much energy is accessible to humans.

===
Also fwiw - The ATP derived from a gram of fat vs sugar is lower than the 9:4 calorie ratio. More of the energy from fat (as a percentage) ends up as heat than in a "usable" form. Of course the heat isn't all "lost energy".
 
stevea said:
I agree T.A.M - the energy (not heat Fnord) equivalence is easy to evaluate, ... {SNIP}
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But is it still true that if I share a quart of ice cream with someone else, the calories in each portion are decreased by half?

;) (I'm having fun with this...)
 
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OK - well here is the paart I don't entirely agree with ...

T.A.M. said:
The body has to take the food we eat, and break it down into its caloric essence (so to speak). To do this with some food, such as simple carbohydrates (bread, potato, pasta, rice) it is quite simple, and is done quite readily. However, for other foods, such as protein, and fibre, the process is much more involved, takes longer, and takes more biological processes. As a result, we (A) lose more of the harder to breakdown foods through transit through and out of the GI Tract, and (B) get less of an insulin spike, and hence less fat storage, through eating these harder to breakdown foods.
Click to expand...

Glucose (easily derived from starch hydrolysis) when consumed transits into cells (the insulin hormone controls transit at the cell membrane) is rectified to fructose1,6-biphosphate as it enters the aerobic glycolysis pathway (citric acid cycle, krebs cycle) however aerobic glycolysis is one of the most complex biological processes around..

The other comments are incorrect. Consumed fat is broken only into free fatty acids and incorporated in fat and muscle tissue triglycerides directly. This is also pretty simple and once past the bile salt solubilisation step, passed from the GI tract to blood and ... very direct and easy. The digestion/adsorbtion of fats is less complete than starches and sugar, but this is not because of some complex process fails to take place in the GI tract. It's just because fat is less soluble and our short intestines (fortunately) are less permeable to larger molecules.

There is a similar story for protein. We consume most protein as animal muscle tissue or plant seed protein and both are rather difficult to solubilize and less likely to permeate across the intestine barrier. We to take both free amino acids and modest size peptides into the blood stream, and IN THE CELL these are broken into aminos and then into separate keto-acids and amine groups before re-use.

So the relatively inefficient adsorbtion of fats and proteins in the GI tract is NOT related to their more complex catabolism later in the cell. They are just harder to get into the blood stream. FWIW fiber (a common plant carbohydrate) is less efficiently used than either fat or protein.

T.A.M. said:
So I guess, depending on where the Calories come from (the food type) the calories can be rapidly available for that burst of energy, but also that energy crash, or it can be available on a more linear (over time) basis, enhancing satiety, and decreasing fat storage (through a more even insulin response).

TAM:)
Click to expand...

The human body has several major component energy destinations. The brain uses something around 20% of all energy ((shocking use of resources considering how few people actually use their brain)) and it requires glucose as an energy source and has no energy storage. Skeletal muscles store a little glycogen (complex carbo) and prefer to fatty acids(FAs) or ketones as an energy source [[glucose for short term exertion]]. Smooth muscle tissue of the heart, arteries use fatty acids or ketones as an energy source with no store. The liver stores a good bit of glycogen to control blood sugar level but can use amino acids, glucose, fatty acids or ketones as it's energy source. The liver is central in supplying non-distributed energy to various organs.

The liver and muscle tissue will take fat (either local or mobilized from adipose tissue) and through beta-oxidation release energy as ketones which then can supply energy. The liver releases ketones to the blood which are then used by organs that use ketone or FAs as energy.
==
So if you go on an "100% carbo" diet, the carbs can be directly used bythe brain and for immediate muscle exertion, but the rest is stored partly as muscle&liver glycogen starch, but primarily converted to fat so it can supply FAs and ketones to organs that require this. Carbos are rapidly convered to fats, as the studies of carbohydrate and hyperlipidemia spell out.

If you go on a "0% carbo" diet, then the fat and protein can each supply ketones to drive the major energy uses. The one outstanding problem is that the brain requires about 120gm of glucose per day. There is a liver mechanism to convert pyruvate to glucose (gluconeogenesis) to supply this need. It is claimed that after extended periods of starvation (on the order of 30 days) that the brain can transition to ketone as an energy source, but I haven't found a great deal of detail on the topic.

So to gain some perspective ... an adult human with moderate activity might require 2000 Cal/day. The adult body contains only 1600Cal of glycogen carbohydrate, about 23000 Cal or mobilizable protein and a whopping 135000 Cal as fat ! I have a bit more than that; at about ~25lbs overweight I carry an extra 100000 Cal of fat !



Let me also say something about fad diet advertising that I think is criminally irresponsible. "Lose 15 pounds in 2 weeks", type statements may be accurate IF we want to lose water and protein, but it's complete nonsense wrt fat loss. One pound of fat is (453gm * 9Cal) about 4000 Calories of energy and you'd have to exercise like a demon AND eat nothing to use so much net energy per day. Perhaps fat only supplies 7.5Cal/gm of "effective energy"(as discussed above) but still such a loss rate is impossible. Now a pound of protein is only 1800 Cal, which is at least possible, but certainly not desirable.

FWIW I happen to believe that much of the Atkins/Zone/S.Beach initial "induction phase" weight loss is due to a reduction in glycogen stores and the water that glycogen retains. OTOH I also believe that a low refined carbo diet makes a lot of sense for fat loss (just my personal opinion, not advise to others).
 
Fnord said:
Since a "calorie" is a measure of heat, and ice cream is frozen, then it stands to reason that you can eat as much ice cream as you want without gaining weight as long as you don't let the ice cream thaw out.

It's twoo! It's twoo!

:runaway
Click to expand...

Not quite ... ice cream runs around 1.5 big-C Calories (1500 calories) per gram, and has about the same heat capacity as water. If you cooled your ice cream to absolute zero (0K, ~505C below body temperature) you'd only knock off about 0.5Cal/gm or about 1/3rd of the calories ! Not my idea of diet ice-cream.

[edit]
Oops - mibad. I recalled the conversion incorrectly. 0K is only ~300C below body temperature so absolute-0-ice-cream would only have about 0.3Cal/gm fewer Calories, 20% less.
 
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Fnord said:
But is it still true that if I share a quart of ice cream with someone else, the calories in each portion are decreased by half?
Click to expand...

Reminds me of Susan Powder calculating the percentage of fat by calories in sliced ham, after which she said "That's thirty percent fat... PER SLICE!". So I guess two slices would be sixty percent fat.
 
Interesting thread... I for one will be taking Fnord's superb dietary advice. Bring on the ice cream! :D
 
stevea said:
OK - well here is the paart I don't entirely agree with ...



Glucose (easily derived from starch hydrolysis) when consumed transits into cells (the insulin hormone controls transit at the cell membrane) is rectified to fructose1,6-biphosphate as it enters the aerobic glycolysis pathway (citric acid cycle, krebs cycle) however aerobic glycolysis is one of the most complex biological processes around..

The other comments are incorrect. Consumed fat is broken only into free fatty acids and incorporated in fat and muscle tissue triglycerides directly. This is also pretty simple and once past the bile salt solubilisation step, passed from the GI tract to blood and ... very direct and easy. The digestion/adsorbtion of fats is less complete than starches and sugar, but this is not because of some complex process fails to take place in the GI tract. It's just because fat is less soluble and our short intestines (fortunately) are less permeable to larger molecules.

There is a similar story for protein. We consume most protein as animal muscle tissue or plant seed protein and both are rather difficult to solubilize and less likely to permeate across the intestine barrier. We to take both free amino acids and modest size peptides into the blood stream, and IN THE CELL these are broken into aminos and then into separate keto-acids and amine groups before re-use.

So the relatively inefficient adsorbtion of fats and proteins in the GI tract is NOT related to their more complex catabolism later in the cell. They are just harder to get into the blood stream. FWIW fiber (a common plant carbohydrate) is less efficiently used than either fat or protein.



The human body has several major component energy destinations. The brain uses something around 20% of all energy ((shocking use of resources considering how few people actually use their brain)) and it requires glucose as an energy source and has no energy storage. Skeletal muscles store a little glycogen (complex carbo) and prefer to fatty acids(FAs) or ketones as an energy source [[glucose for short term exertion]]. Smooth muscle tissue of the heart, arteries use fatty acids or ketones as an energy source with no store. The liver stores a good bit of glycogen to control blood sugar level but can use amino acids, glucose, fatty acids or ketones as it's energy source. The liver is central in supplying non-distributed energy to various organs.

The liver and muscle tissue will take fat (either local or mobilized from adipose tissue) and through beta-oxidation release energy as ketones which then can supply energy. The liver releases ketones to the blood which are then used by organs that use ketone or FAs as energy.
==
So if you go on an "100% carbo" diet, the carbs can be directly used bythe brain and for immediate muscle exertion, but the rest is stored partly as muscle&liver glycogen starch, but primarily converted to fat so it can supply FAs and ketones to organs that require this. Carbos are rapidly convered to fats, as the studies of carbohydrate and hyperlipidemia spell out.

If you go on a "0% carbo" diet, then the fat and protein can each supply ketones to drive the major energy uses. The one outstanding problem is that the brain requires about 120gm of glucose per day. There is a liver mechanism to convert pyruvate to glucose (gluconeogenesis) to supply this need. It is claimed that after extended periods of starvation (on the order of 30 days) that the brain can transition to ketone as an energy source, but I haven't found a great deal of detail on the topic.

So to gain some perspective ... an adult human with moderate activity might require 2000 Cal/day. The adult body contains only 1600Cal of glycogen carbohydrate, about 23000 Cal or mobilizable protein and a whopping 135000 Cal as fat ! I have a bit more than that; at about ~25lbs overweight I carry an extra 100000 Cal of fat !



Let me also say something about fad diet advertising that I think is criminally irresponsible. "Lose 15 pounds in 2 weeks", type statements may be accurate IF we want to lose water and protein, but it's complete nonsense wrt fat loss. One pound of fat is (453gm * 9Cal) about 4000 Calories of energy and you'd have to exercise like a demon AND eat nothing to use so much net energy per day. Perhaps fat only supplies 7.5Cal/gm of "effective energy"(as discussed above) but still such a loss rate is impossible. Now a pound of protein is only 1800 Cal, which is at least possible, but certainly not desirable.

FWIW I happen to believe that much of the Atkins/Zone/S.Beach initial "induction phase" weight loss is due to a reduction in glycogen stores and the water that glycogen retains. OTOH I also believe that a low refined carbo diet makes a lot of sense for fat loss (just my personal opinion, not advise to others).
Click to expand...

I have no issue with most of what you have stated...but.

1. I did not address fats in my comments.
2. I did not mention cellular breakdown or absorption, but rather was speaking of breakdown in the GI tract. Rereading my original post, however, I can see where I was ambiguous enough that it could have been taken that way...I apologize, I meant to strictly refer to absorption from the GI Tract, not breakdown at the cellular level (bad original wording on my part).
3. Do you have some issue or argument with the insulin spike and subsequent Fat storage caused by the ingestion of large amounts of simple carbohydrates
4. I am not a proponent of any one diet, as they all have their faults, and most of them are too hard to stick to for long term loss. I think a good reduction in simple carbohydrates (with subsequent increase in high fibre foods), along with a diet healthy in the RIGHT Fats and RIGHT proteins, is the best combination, and allows for the most variety and maintenance longevity.
Of course Exercise is also to be recommended as a large component.

Thanks for the reply.

TAM:)
 
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stevea said:
So the relatively inefficient adsorbtion of fats and proteins in the GI tract
Click to expand...

What exactly do you mean by "inefficient" ? That not all ingested fat and protein will be absorbed in th GI tract ? And if yes, do you have any numbers for this ?
 
T.A.M. said:
I have no issue with most of what you have stated...but.

1. I did not address fats in my comments.
2. I did not mention cellular breakdown or absorption, but rather was speaking of breakdown in the GI tract. Rereading my original post, however, I can see where I was ambiguous enough that it could have been taken that way...I apologize, I meant to strictly refer to absorption from the GI Tract, not breakdown at the cellular level (bad original wording on my part).
3. Do you have some issue or argument with the insulin spike and subsequent Fat storage caused by the ingestion of large amounts of simple carbohydrates
4. I am not a proponent of any one diet, as they all have their faults, and most of them are too hard to stick to for long term loss. I think a good reduction in simple carbohydrates (with subsequent increase in high fibre foods), along with a diet healthy in the RIGHT Fats and RIGHT proteins, is the best combination, and allows for the most variety and maintenance longevity.
Of course Exercise is also to be recommended as a large component.

Thanks for the reply.

TAM:)
Click to expand...


Thank TAM - and apologies - I did not mean to offend.

1. Right, but fat, protein and carbs are the three macronutrients and the source of nearly all calories; so it's fair game in any discussion of diet and bio-energetics. . We should probably add alcohol to the modern diet as it is technically a carbo but is metabolized to acetaldehyde, then lactate and used by smooth muscle tissue or converted to fat. Anyway lactate is an important minor side energy source.

2. "breakdown the the caloric essence" sounds like catabolism to me, but so be it.

3. No; basically right. Insulin is (or should be) released as a direct consequence of a rise in blood sugar level and it permits the ingress of sugars into cells; brain, muscle and liver alike. If the others don't use it the liver will produce fatty acids in the blood (serum glycerides) which then accumulate in the adipose tissue as blubber(technical term). So yes a simple carbo consumption spike causes a blood glucose spike which causes an insulin spike. True - but a hearty "so what?". The statement implies that there is something wrong with an insulin spike, but in fact it's exactly what we want whenever blood sugar levels get high. There is a not-well-founded implication that insulin spikes cause type2 diabetes which are part of the "metabolic syndrome", but there isn't really much evidence. in favor of this assertion.

4. Nothing to disagree with there. I will expand on one idea; that most "diets" are too hard to maintain long-term.

I (like most people I imagine) got overweight a few pounds per year over many years. 3lbs of annual blubber represent 12000 Cal/yr or an extra 32 Cal per day. Now 32 Cal/day is an extra 3/4 tsp of fat/d or an extra 1.5 tablespoons of cooked rice/day or an extra 224Cal sliver of apple pie per week. IOW it takes only a tiny energy imbalance (<2%) to average up by 3lbs per year. Every 365 days I'm eating enough food for 371 days. *SOMEHOW* our bodies are able to detect the energy intake and output and control the two pretty accurately - but I, and a lot of 1st worlders, have a net energy imbalance around ~1.5%. There is an active functioning control system here (I'm not gaining 30lbs or 50lbs per year and neither am I watching my diet) but it has a consistent long term bias toward slow weight gain.

I *believe* that the problem is that some factor is causing the net bias in the control system. Perhaps some item causes our control system to not be satiated when we eat of "normal" and correct size meals. I'm quite willing to entertain the idea that refined carbos are the problem, but that's far from clear. It might be dry-cleaner fluid or rancid fats in processed foods, or the constant drivel from cable news commentators. One related fact is that in pre-industrial societies it took a full days effort to collect 1700-1800 Calories, whereas today you can get this in a single meal for $3.59 at the local fast-food establishment; perhaps it's just the easy access to food a the heart of it ! We didn't evolve amidst such plenty, and the modest weight gain after adolescence isn't very damaging to our Darwinian fitness.

Eating is a stong survival urge and I don't believe than any normal human can long resist eating food (if available) when they feel hungry. Like it or no, you are going to eat till you approach near satiety. I *suspect* that calorie for calorie processed carbs are not satiating, but instead they make you feel hungry for more (the addiciton effect). Any practical means to lose weigh (surgery aside) must involve feeling satiated on fewer catabolized calories. Low-carb diets *seem* to offer this to many people. I'm impressed with how satiated I feel on a mostly protein&fat diet, but I'll also note that high fiber foods are amazingly 'filling' too.


thanks T.A.M.
 
El Greco said:
What exactly do you mean by "inefficient" ? That not all ingested fat and protein will be absorbed in th GI tract ? And if yes, do you have any numbers for this ?
Click to expand...

Yes, some of the calories you consume pass through the GI tract untouched. It depends greatly on your total diet. A very interesting little book I used to own (title "Why the Reckless Survive" I think) was written by a physician, and has a chapter considering the claims made in favor of the "paleolithic diet" (aka hunter-gatherer). He pointed out that their projected diets would have been very high in plant fiber compared to ours and although he stated that they consumed higher levels of total fat, they would have digested less as it adheres to and is trapped in the plant fiber.

I've also seem some more detailed figures in one of the National Academy of Science books, primarily describing micronutrients. I recall that humans retain anywhere from 40% to 80% of cholesterol eaten - and that there are wide individual variations. I also saw some numbers for fats & proteins , but I'll have to dig for that reference.
 
This doesn't seem plausible to me. Of course it depends on the total diet but I'm not talking about cases like extreme caloric consumption or rather high carbohydrates after a period of greatly reducing them (in both cases more or less food will not be absorbed). But if one eats a normal meal of any combination of protein, carbs and fat, I have seen no study showing that absorption of nutrients will not be nearly complete.
 
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