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Comment by tezza | Hacker News Reader

> 9 Kcal/g for fat. [...] These numbers were originally determined by burning

This method for calculating the calorie count for fat has in my opinion allowed the demonisation of fat.

Our stomachs are imperfect at digesting globules of fat. Burning-until-gone releases much more of the energy than surface acting acids and proteinases.

Effective calorie count for fat just has to be so much lower than the listed value.

Constrast that with sugars, where the absorbtion mechanism is crystaline dissolution. Disolving crystals is an almost perfect 1-1 process

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Agreed. 500 calories from chicken or a lean protein like crab is very different from 500 calories from a pastry. What should be highlighted is amount of sugar and carbohydrates, not total calories. Not every calorie is created equally. In fact, you could almost remove carbohydrates from your diet and be unaffected, but the same isn't true of protein and good fats.

It is of course different. Carbohydrates, protein and fat all undergo different metabolic pathways. Further down you are wondering why you might not have a high karma on this post. I think it's because what you have written conflates 2 issues (I suspect, though, that you aren't actually conflating them... just your writing is unclear).

500 calories from whatever source is 500 calories, when we are talking about energy. It is definitely possible for people to excrete excess calories, but if for example you are excreting a lot of fat, you will know about it. It is not pleasant. There are a fair number of people who are unfortunately misinformed and think that somehow they have super digestion for carbohydrates for example. They think they can extract 1000 calories from 500 calories of carbohydrates. This is impossible and it's why it's important to understand that from that standpoint a calorie is a calorie.

Of course nutritionally they are very different things. They are digested differently, at different speeds and metabolically burned in completely different ways. Different foods also have different nutrients and it is important to make sure that you get these nutrients. You can go an awfully long time without any symptoms being malnourished only to eventually come to a very serious problem.

So many people are (for lack of a better word) arrogant in their beliefs about nutrition. However, we still know very little about how our body works. Traditional diets have a long track history with many, many people. We have a good idea about potential nutritional problems and how to counteract them.

I was vegan for many years (although, strangely, not ethically vegan -- I just enjoy eating that kind of food). I have seen many invented diets cause serious problems and eventually I spent considerable effort to learn about traditional vegan diets. I'll caution you that the current attitude of "You can just cut out carbohydrates from your diet and be healthier" is unlikely to be true. Nutrition is complicated and can't be boiled down to something so simple. There are many shapes of diets that can be healthy but seemingly insignificant changes can take their toll on your long term health. Please exercise caution.

> I'll caution you that the current attitude of "You can just cut out carbohydrates from your diet and be healthier" is unlikely to be true.

I have a lot of sympathy for your conservative and skeptical stance in general.

I am glad though, that a lot of people have done the self-experimenting (that we probably wouldn't do to normal experimental subjects) and gone on a low carb diet.

They seem fine.

There are also some better monitored people on a low carb diet, eg for some kids with epilepsy it's the only thing that works. The kids main problem is usually getting enough calories, but not any lack of other nutrients. (I think the go to source of extra calories is coconut oil, because the kids seem to mind that the least.)

See eg http://www.nytimes.com/2010/11/21/magazine/21Epilepsy-t.html...

Edit: just checked the article above. Looks like they need to add multivitamins etc. Poor kid: his diet needs to be much more extreme than eg Atkins diet to keep the epilepsy at bay.

We've evolved as omnivores with unfussy requirements and highly efficient metabolism

Mikekchar, "500 calories is 500 calories" is a tautology and neither a clever writing device nor a serious argument.

I've cut carbs out of my diet a few months ago, after I chewed through the 200-pound mark. I noticed I had trouble running, walking and even standing. I dropped bread, pasta and refined sugar, though I still eat fruits without restriction.

The result is that I've been steadily losing weight and shedding fat, primarily the nasty layers found in the pubic area.

My research has thoroughly convinced me that carbless diet makes the body burn fat and serves as a protective factor against neurodegenerative diseases.

I'm glad you are losing weight (if that's what you are trying to do). However, when you change your diet comprehensively it is easy to overlook changes. For example, did you seriously measure your caloric intake before and after you changed your diet? Are you sure that you did not overlook sources of calories?

I helped a friend of mine lose weight once. His original diet consisted of a single muffin and coffee for breakfast, a subway sandwich with iced tea and one of those tiny bags of potato chips that come with the meal, and for dinner some salad and spaghetti or something. It sounds reasonable, but for the life of him he couldn't get under 220 lbs.

We went through the numbers. The muffin he was eating was 500 calories! The chips, 150 calories. The salad dressing he was eating on his salad was over 100 calories. The ice tea was 180 calories. So that's 930 calories, or nearly 1/2 of his daily requirements in just those 4 items of food.

We made a few minor substitutions to his diet (which actually increased the volume of food he was eating) and he started running 2 miles a day with me at lunch (which is worth about 200 calories a day). He was down to 160 pounds in no time. Our biggest problem was trying to make sure he didn't lose more than 2 lbs a week because that can be hard on your liver.

The thing is, if he had gone on a no carb diet and found alternatives in his diet he probably would have had the same result. No muffin. No potato chips. No ice tea. Probably substitute the salad for something with more protein.

Like I said, I'm happy if its working for you. I know a lot of people on low carb diets. Every single one of them is overweight. I have yet to meet even a single person in real life for who this strategy has worked. Mostly I see people change their diet, lose some weight when they eat more healthily and then gain it back when they mistakenly think that as long as they keep out the dreaded carbs, then they can eat whatever the heck they like without consequences.

i don't understand why your comment scores so low. It's pretty clear that our bodies will absorb 500 sugar/carbohydrate calories much more quickly than 500 protein/fat calories. You will get a much greater insulin response when eating a pastry than a chicken breast.

I suspect I'm being down voted because I said I don't believe carbohydrates are required for survival.

While glucose is essential for life since the brain cells die quickly without it, glucose does not have to be obtained from carbohydrates. It can be obtained from protein or fat by breaking down the protein or fat into glucose. In fact, a good percentage of protein (~50%) becomes glucose when it enters the body.

Protein is favored over many other energy forms since it contains amino acids, one of the most useful sources of nutrients to your body. Your body cannot store amino acids and yet it needs a daily intake of amino acids to survive. Additionally, protein conversion to fats is costly, so your body under normal conditions does not usually convert much of it, compared to fats and carbohydrates (carbs almost immediately undergo storage). Good fats, however, are beneficial (essential even for health) than carbohydrates in all cases.

Or perhaps someone might enlighten me why I'm wrong (at the time of this writing, my original comment has 0 points of karma).

I've cut bread and processed sugar to a large degree from my diet and stick to lean proteins like seafood and chicken, and have found myself to be quite lean and healthy (bulking even with my anterior/posterior chain, triceps/biceps). I haven't counted calories since I switched to a diet that focuses on lean protein and seafood (and I suspect there are days where I eat more than 2000 kCal).

Not true at all. The brain runs just fine on ketone bodies in the absence of dietary glucose.

The few organs that do require glucose are supplied by protein conversion (gluconeogenesis).

I can't add anything constructive to your glucose conclusions, though I can say that eating 2 medium chicken drumsticks with skin has made me satiated to a degree I never thought possible.

I too experienced a certain effortless growth of muscle mass after eating enough protein for my daily needs, too.

It's a function of diet and exercise. "Absorb" also begs the question "for what?" Your body can absorb protein and repurpose it into other proteins for muscles or whatnot, but turning that protein into energy is harder.

It's like saying that a city can absorb a terajoule of gasoline more easily than a terajoule of coal or a terajoule of lithium batteries. It's true, but "which is absorbed faster?" is a vast oversimplification of a more complicated question, which is "how much is needed?"

To extend the analogy further, if a city had mostly electric cars and a coal power plant, it would have no trouble absorbing the lithium batteries or the coal, but would have more trouble absorbing the gasoline.

It's a well understood process:

https://courses.washington.edu/conj/bess/fats/fats.html

Also, you can experience what happens when you don't digest fat by eating a good bit of Olestra.

https://en.wikipedia.org/wiki/Olestra#Side_effects

don't eat olestra

Also dont eat fish oil capsules on an empty stomach. Your Herman Miller chair will receive a present that you could not help deliver. The oil will literally leak out since there is no other digested food to keep it behind your sphinter. One of the weirdest stenches of partially digested fish oil bile that resists all attempts to nuetralize the stain and odor. I am passing on great wisdom as funny and crude as it sounds..(That chair was eventually sold at a huge discount and was probably bleached. Steelcase Worklounge is better anyhow so I'm not totally out of shape about it.)

This isn't so. Quoting [1], energy dissipated as side-effect heat during gestation and storage:

Carbohydrates: 5 to 15% of the energy consumed

Protein: 20 to 35%

Fats: at most 5 to 15%

[1] https://en.wikipedia.org/wiki/Specific_dynamic_action

> Protein: 20 to 35%

Doesn't this assume that you're starving [1]? Proteins are a last resort, and since it's somewhat toxic to convert them, they're simply not processed if it can be avoided [2].

[1] https://en.wikipedia.org/wiki/Gluconeogenesis "the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise."

[2] http://antranik.org/the-catabolism-of-fats-and-proteins-for-...

Yes, looks like this. And in addition in average human this pathway is limited to 300g amino-acids -> glucose per day if I remember correctly. Still what should happen if protein intake is tripled say from 50g/day to 150g/day? Excess amino acids have to go somewhere...

This adds to my point, it does not subtract to my point.

Not only is the fat digestion process inefficient, but on top the fat absorbtion process consumes more energy to make happen ( that heat )

We'd have to see where in the large 5-15% ranges various items stand.

Sugar dissolving in water... I'd be amazed if that released 15% of the energy. I'm still amazed it would be as high as 5%, so thanks for that info

EDIT: spatular set me straight with a detailed process for sugar absorbtion

Well, fat digestion seems to be effective even comparing to hydrocarbons.

I think longer hydrocarbons including sugar have to be broken into fructose and glucose during digestion. Fructose cannot be immidiately consumed by cells, so it's converted into glucose in liver. On top of that, there are about 5g of glucose total in bloodstream at any given moment, so exess have to be accumulated by liver/muscle cells that have to store it in a long-chain hydrocarbon form (glycogen). Each conversion requires some energy, so 5-15% isn't that much...

same thing is for protein present in grass but indigestible for humans.

cows can extract "enormous" amounts of protein from foods that humans wouldn't ever.

it's very hard measuring how much digestible protein something has, such as beans, or lentils, or soybeans. it depends if you eat the shell, did you blend the shell like a mad man, even if you blended beans into a homogenous phlegm

Cows are not extracting protein from grass (well not much), they are converting the cellulose in the grass into microorganisms and then extracting the proteins from the microorganisms. The ruminant digestive system is an amazing system [1].

1. https://en.m.wikipedia.org/wiki/Ruminant

You mean, microorganisms allow better deconstruction of cellulose which then frees the protein and makes it digestable?

Yeah, ruminants are amazing with their cyclic puking and eating :)

Cows actually can't digest cellulose at all - what they can do is harbour the microorganisms that can. These microorganisms are then eaten by the cow and provide most of the protein in a cows diet.

The body is very efficient in storing fat, more than carbs or protein. But burning fat is inefficient. But this is just from the top of my head.

I think its just a lot easier to eat a lot of carbs. Fats and protein make me much more saturated more quickly.

I don't think there is some magic formula.

> burning fat is inefficient

Huh? The body is perfectly happy to burn fat. You just have to give it the right conditions. In fact, the body can get practically all its energy from fat, it's called ketosis. You can achieve a state of ketosis either through a high fat, low carb diet or fasting.

Yup. I've been doing a ketogenic diet the past 6 weeks and it's pretty awesome.

In general your body doesn't take the fat you eat and store it as fat. It takes the excess sugars and stores them as fat.

Maybe we have differing ideas of "general" but in healthy non-overeating people, the fatty acid profile in the body is reasonably close to the dietary profile. There is some conversion like elongation and desaturation of essential fatty acids and you can also find some short-chain fatty acids from fermentation in the gut, but it takes excessive amounts of carbohydrates for de novo lipogenesis. Also, what else would the body do with dietary fat other than storing? A fatty meal would quickly overwhelm the capacity of the blood if there was no mechanism to quickly dispose of dietary fat.

Storing fat? ... You know have to burn the the fat to be able to store it? The fat doesn't have some other pathway from stomach to body fat - all the 'fat' you carry has been burned to get there. So whatever you have been overeating will be the cause.

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