Is the concept of "Negative Calorie Foods " scientifically true or not ? There are more articles on the internet about it being true than it is not.
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Is the concept of "Negative Calorie Foods " scientifically true or not ? There are more articles on the internet about it being true than it is not.
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No far as i know it's impossible, calories is a measure of the intristic energy of a food based on burning it, to raise 1 cm of water 1 degree celius. Negative Calories implies a reverse of the process of burning.
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A glass of cold water is the simplest example, it has no energy and requires an expenditure of energy to heat the body back up after drinking it.Originally Posted by dgavin
This counter-example of your hypothesis should be enough to show that the concept is not intrinsically impossible.
Making something that is actually food-like and edible while requiring more energy to digest than is obtained from metabolizing it would be a rather hard undertaking though.
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indigestable substances (ie., cellulose) require energy to process (chew) and transport through the body but provide zero nutritional value. I've never heard the term negative calorie, but often heard that celery takes more energy to process than it delivers, in that sense eating such items might be considered to be a negative net calorie endeavor.
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Actually, you're starting out by being wrong here.
You probably meant cm[sup]3[sup] there and that's still wrong, first of all it should be 1 gram, not 1 cm[sup]3[sup], and the calorie used when talking about food is actually 1000 thermodynamic calories, i.e. the energy required to heat 1 kg of water from 14.5 °C to 15.5 °C.
Since the food calorie is already one stop away from the thermodynamic definition it takes an extreme purist1, who shouldn't be talking about calories anyway as they've been superseded by kJ, to reject the concept of negative calories for food that cost energy to eat.
1) or an accountant since they apparently have no concept of negative numbers, having replaced them with "numbers in the other column".
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Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain
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Order of Kilopi
It's not impossible, a food can take more calories to digest than your body receives from it, but it really isn't much of a difference; the negative calories are generally insignificant.
Still, it's probably a fairly good way to keep your mouth and stomach occupied so you don't snack on more calorie dense foods.
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I completely disagree, by definition The measure of calories is how much energy a food gives, -not- how much it takes to digest it. There is no food with less then 0 calories.
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i think you may be thinking too hard and applying the wrong definition.. i've often heard that lettuce is a "negative calorie food" because it takes more energy to digest it than the body gets from it.
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I think that when people say "negative calories," they mean foods where the amount of energy required to digest is larger than the amount of energy gotten from the food. It may be inaccurate but it seems like a reasonable idea. Maybe a different term would be better. But I think that for example, eating uncooked rice would have a negative balance because we can't digest it. You might argue at that point that it's not "food," but that depends on whether food means nourishment or whether it means something you can put in your mouth and enjoy eating (not that raw rice is enjoyable). But water. Is water food?
As above, so below
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Further research shows that you are right.
However, if water counts as a food, it may be the only example as an ice cold glass of water takes calories to heat up to body tempereture but contains 0 calories.
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Following often appear in the list :
Asparagus
Broccoli
Cabbage
Carrot
Cauliflower
Celery
Spinach
Cucumber
Tomato
Apple
Blueberries
Cranberry
Grapefruit
Raspberry
Strawberry
Tangerine
Orange
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Those are definitely all wrong, there's far to much readily available sugar in all of those to have negative net energy.
__________________________________________________
Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain
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I've searched around a few sites, and the calorific values reported vary a bit from site to site, but it would appear that cucumber and celery are the lowest calorific value of the usual vegetables mentioned at around 7 to 14 kCal / 100g according to who you believe. Mushroom is also rather low, and lettuce in fact a touch higher. I've seen tomato reported at about the same as grape, though the sweetness of tomatoes is rather variable.
I was a bit surprised about konjac because it is very starchy, but apparently the polysaccharide present is not digestible. Nevertheless it will have some calorific content - but see the comments below.
In a few moments I couldn't find detailed info on the energy cost of digesting particular foods. But it would be typical for an adult to consume about 200 kCal a day digesting their food, so I wouldn't be surprised if the tougher-to-digest foods were consuming a fair amount of this.
Calorific values have traditionally been assessed by burning the food in a bomb calorimeter. This assumes that the entirety of the food is digestible, whereas in practice there are "inaccessible" calories in dietary fibre, etc. Some sources may now take account of this, which may explain why I found a range of values for the calorific values of some foods. Describing Konjac as near-zero would not be by calorimeter method.
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Call it a Net Metabolic Negative.
Et tu BAUT? Quantum mutatus ab illo.
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I'm not saying that there isn't food that takes more energy to process they they give off, just that the term calorie has a specific meaning, and 'negative' does not fit with it's meaning.
It's akin to using Military and intelligence together...
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To be fair the little c calorie is scientifically defined but in common usage the kilocalorie or big C Calorie was coined for food use so although there is a link it is fair to redefine the Calorie in net terms so some foods could cost more than they provide although they may also contribute vitamins and proteins for example, essential to life. And the calories you reap from a scientific calorimeter might be very different from the Calories gained in digestion.
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Actually I doubt you'd reap any calories at all from a scientific calorimeter unless you have very strong teeth and a very hardy stomach.
As above, so below
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It is sometimes claimed that konnyaku provides fewer calories than it takes to process. Whether it counts as "food" can be debated.
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Considering rotten shark meat that smells like household cleanser is food, I think a bland gel qualifies just fine.
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Raw potatoes are normally indigestible because humans cannot break down the cellulose walls however if the potato is chewed for a long time the Ptyalin enzyme in saliva will convert the starches to sugars and then you can live on raw potatoes. I suppose carrots and other starchy roots are similar. So they go from negative to positive if you chew on it.
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I thought potatoes needed to be cooked to destroy the toxins, as well? (I'm sure the FDA would never allow them to be eaten if they were discovered today.)
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I think you are referring to oxalic acid which can form if the potato is exposed to light, it is toxic and it is destroyed in cooking. Otherwise the potato can be eaten raw if chewed to destruction. (chew one hundred times I heard)
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Oxalic acid is in rhubarb and some other plants.
http://en.wikipedia.org/wiki/Oxalic_...ence_in_natureOxalic acid and oxalates are present in many plants, including black tea,... Its presence makes it dangerous to eat unripe carambola or monstera fruits. Members of the spinach family are high in oxalates, as is sorrel ...
http://en.wikipedia.org/wiki/Potato#ToxicityPotatoes contain toxic compounds known as glycoalkaloids, of which the most prevalent are solanine and chaconine. Solanine is also found in other plants in the family Solanaceae, which includes such plants as the deadly nightshade (Atropa belladonna), henbane (Hyoscyamus niger) and tobacco (Nicotiana) as well as the potato, eggplant, and tomato. This toxin affects the nervous system, causing weakness and confusion.
I don't think they can kill you, but they can make you ill.
They also taste horrid raw, so I'm not sure why you would bother. Mind you, I'm not too keen on them cooked either. I did read somewhere that the Incas would grow potatoes, dry them and then bury them in case of famine. Sounds like a good approach to me.
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Thanks for that, I am happy to be corrected; the raw potato story comes from prisoners of war given only raw potatoes. I have seen gardeners eat raw new potatoes fresh from the ground. For me the proper Belgian frite cooked twice is the perfect way to eat positive Calorie spuds.
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You have got the Andean business a bit mixed up. You are referring to chuño, which is freeze dried potato (I won't go into the technicalities), as commonly found in highland Peru and Bolivia, at least. Now making chuño does have the benefit of preserving it. But one of the main benefits of making chuño is that it reduced the alkaloids and made the potato edible. It turns out that high altitude grown potatoes are, or at least were in the past, particularly high in alkaloids. There are today low alkaloid varieties that can be grown well at high altitude, and that is mostly what is grown today, so it is no longer necessary to make chuño for that reason.
Nevertheless, a lot of chuño is still made and eaten. I found this interesting, because I found that it tasted pretty horrid. So I asked a local why they still make so much chuño - is it to preserve it? No, he replied, you can get fresh potato year round cheaper than chuño. It's because we like the taste. Moreover he bemoaned the fact that, because it is labour intensive to make it, it becomes increasingly expensive. In fact it was common to find both fresh potato and chuño present in the same dish.
While on trek in the high Andes, it was not uncommon to see that where a narrow stream ran through fairly level pasture in a high valley bottom, typically in a fairly narrow steep sided ditch, and typically a tributary of the main water-course in that valley, a series of round pits a metre or so across and similarly deep had been dug along the water course, so make some pools of well aerated water. These are for making the more expensive variety of chuño which involves soaking the potato in these pools for a week or so. Every now and then the potatoes are lifted out in a net and thrown around in the air before being put back in the pool. In one remote valley, we actually saw this happening.
I learned an interesting lesson about myself from chuño. I was cycling through the high Andes in Bolivia, and, when possible, I would stop to have lunch at a "lunch stop". The first time I did this, I asked what was for lunch, and was told it comprised soup and main course. This was a rather less specific description than I had hoped for, but I decided to take the plunge, it only cost $1. The soup was typically a clear soup containing large chunks of potato and other root vegetable, and a chunk of meat. The main course was typically more or less identical to the soup just eaten, but without the liquid. Often some of the potato was in the form of chuño. After a while, I thought to myself, rarely am I so hungry that I bother to eat things that taste horrible, but I've been so hungry up here that I've even been eating chuño. This therefore encouraged me to try some other things that I normally didn't bother with on grounds of taste, but were at least available here. So I bought some bananas, when I next saw some, something I had refused to eat since I was a child and we had moved back to England from a place where the bananas were tree-ripened and much nicer, at least in those days. In smaller places, in highland Bolivia, bananas and oranges were the only fruit available, and often not even those. I quickly learned bananas were a lot nicer than chuño, and I quickly started to eat a lot of them. I now eat bananas again.
Order of Kilopi
People often get a liking for the foods that are only available from the necessity of preserving them. And then people from other cultures often find them distasteful. The shark mentioned earlier, pickled onions, natto, dried cod, cheese, kimchi, ...
(Actually, I like at least three of those)
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Maybe I should make a better point of this. Isn't using Negative Calorie together exactly the same as using Conspiracy Theory together? And if one mis use is considered acceptable why not the other...
I realize at times fad usages of words become accepted, but I was taught by this very own forum that 'Conspiracy Theory' was just wrong, and why it was wrong. I see the same exact situation with the term Negative Calories is all.
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I think this is not any conspiracy issue. Calorie is widely used in diet work (good and bad) and in that context negative Calories just means the food including cold water takes more Calories from you than you can get by digesting it. Digestion and fat use issues are complex but the concept of negative calories in that context is just a shorthand. Of course it can be abused and misunderstood. but that is different.
Order of Kilopi
Note that even though it's wrong from a linguistic constructionist point of view, we still happily use it because it's a noun phrase with a well-defined and generally well-known meaning.
Same as Negative Calories which is a phrase used specifically to refer to food with a negative net caloric yield.
Such phrases need not have the meaning logic would dictate because they're defined by use rather than by logic.
__________________________________________________
Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain
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