
Walnuts Have Fewer Calories Than the Label Suggests - nkurz
http://blogs.usda.gov/2015/12/03/walnuts-have-fewer-calories-than-the-label-suggests-ars-researcher-discovers/
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dogma1138
TBH that's true for most foods (not necessarily less but not exactly what the
label says).

The most common way of calculating the caloric value for food is by
calculating the fat, fatty acids, proteins and carbohydrates by weight and
assigning them the common caloric value this in itself is not accurate to
begin with. The more accurate way is going to be by testing the overall
caloric potential of the food before digestion and then checking the caloric
value of the fecal mater after digestion, but that isn't something easy to do.

If you are selling a hand made sandwich that data might be available for most
ingredients and you'll end up having quite an accurate caloric value. But with
many processed and mass produced food products that's simply not the case as
it's quite hard to estimate what exact caloric value your body would extract
from each portion with so many ingredients from various sources.

The biggest problem is that not all foods are digested the same way this is
both universal e.g. foods with higher percentage of non soluble fibers reduce
the caloric value (10-30%) and non-universal per person specific metabolism,
your personal digestive track biome and many other factors like how much
activity have you done before and after eating.

Eating a more or less rounded meal on an exact schedule and a very mild
exercise (like a casual walk) shortly after the meal can reduce the amount of
calories your body extracts from the food quite considerably.

Now it's true that genetics and some other circumstances play quite a big
role, but eating on schedule and not sitting straight after heaving your food
can do wonders for some one who is trying to either lose or maintain weight.
Yes burning a couple 1000's of extra calories a week at the gym can do wonders
but in many cases it's not as effective as proper diet management and diet
management isn't about counting calories is about finding a good combination
of what your body will digest well but not over digest and teach your body
that it doesn't need to hoard everything because it knows that the next meal
will come on time.

When you eat regularly and induce a system in which your body would rather
metabolize what it needs straight away and use that instead of hoarding
everything and converting it to fat while burning your glucose reserves (which
what induces the odd hour cravings) works better than just counting calories.
You can have 2 people eating at exactly their BMR with the same caloric intake
and outtake and one would lose weight and the other would gain it just because
one eats regularly 4-5 times a day and the other eats irregular meals and
snacks when they feel hunger.

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bjterry
> But with many processed and mass produced food products that's simply not
> the case as it's quite hard to estimate what exact caloric value your body
> would extract from each portion with so many ingredients from various
> sources.

Generally speaking, processed foods are more likely to achieve the full
thermodynamically available calories, because most of what we consider
"processing" makes things more digestible. For example, if you create Cheetos
out of corn, you grind corn into meal, then bake it or whatever. When it goes
into your stomach, it readily dissolves into an easily-digestible soup of corn
specks and oil. If you just eat corn, the kernels have much less surface area
available for the digestion process and some parts remain (notoriously)
undigested.

That means it's pretty easy to calculate the number of calories that highly
processed foods contribute, since it's near the theoretical max.

~~~
dogma1138
In theory yes, but in practice it's much more complicated than that. During
the protein crave of the late 90's early 2000's we added protein to everything
because doctors said we aren't eating enough of it. Wheat protein was one of
the easiest and the cheapest to work with which is now why we are now having
to search for Gluten free dairy products which wasn't an issue 15 years ago.
After proteins fibers became the biggest crave so the food industry found
another cheap source for them - boiled saw dust from pine trees. Processed
food isn't simply just ground nutrition it has some really really fucked up
stuff in it (fucked up as in weird not indicatively bad).

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blakesterz
The full text is online:
[http://jn.nutrition.org/content/early/2015/11/18/jn.115.2173...](http://jn.nutrition.org/content/early/2015/11/18/jn.115.217372.full.pdf+html?sid=6785fd43-b687-408d-9d27-bf92ab7ca436)

Apparently studies have shown the same thing on pistachios and almonds too.

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hayksaakian
This is a study of 18 people.

Take that with a grain of salt, but also realize that many studies on people
tend to have really small numbers of people.

~~~
iopq
That only matters if results differ between each person. If everyone has the
same results, 18 people is plenty to prove that the results are the same for
everyone. It depends on the sample variance and the number of people. If you
have high sample variance, you need a higher N to make it less likely that you
have a sampling error. If you have very low sample variance, just a few people
is enough.

~~~
thaumasiotes
> That only matters if results differ between each person.

Well, we know that they do...

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iopq
We actually DON'T know that. It could be every person gets almost the same
result.

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amluto
Awhile back, I tried to find the actual studies that determined that sugar has
4 kcal/g and fat has 9. I failed. I couldn't even find a clear definition of
what a kcal _means_. (Is it mechanical work you can do after eating it? ATP
produced?)

Given recent results, I wouldn't be at all surprised to learn that fat, in
general, has less than 9 kcal/g or that sugar has more than 4.

~~~
InclinedPlane
One calorie is the energy required to raise the temperature of one gram of
water at 1 atm pressure by one degree Celsius, it is equal to about 4.2
Joules. A kilocalorie, or a dietary Calorie, is one thousand calories, or 4200
Joules. All of this is readily available from an innumerable number of
sources.

The calorie content of food is determined experimentally by burning the food
in a calorimeter and measuring how much heat is produced (by, for example,
measuring how much it raises the temperature of a water bath). This measures
the energy content of the food, but does not measure the amount of energy your
body can make use of as that is a very complex problem that would have a
different answer in every individual due to variations in body size,
metabolism, digestion, muscle mass, insulin activity, the ambient temperature,
and about a zillion other factors.

~~~
NikolaeVarius
We haven't done that since the 1990's.

Calorie content is calculated by measuring the amount of fat, protein, carbs
in a food and extrapolating from that.

It's pretty damn close.

~~~
InclinedPlane
Perhaps I wasn't clear, I said that's how calories are determined
experimentally, I did not say that's how all calorie counts are generated.

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nostromo
> The study was partially funded by the California Walnut Commission.

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Avshalom
I mean yeah but on the other hand, who the hell else would bother funding
calories-in-nuts studies?

~~~
blakesterz
Yeah, I kinda feel like that too. I'd like to think they saw the results of
other studies and just thought "Oh wow it would be great if we see the same
results on our walnuts. On the other hand, the California Nut Industrial
Complex could just be pretty evil.

~~~
jessaustin
Maybe it's because I lived there a couple of years, but if I saw that phrase
in another context I wouldn't think of walnuts and almonds. b^)

~~~
ant6n
[https://en.wikipedia.org/wiki/Nut_(goddess)](https://en.wikipedia.org/wiki/Nut_\(goddess\))
?

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daveguy
Judging from the amount that just passes right through I would have expected
even less than 80% of the calories absorbed!

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jessaustin
The tag cloud is hilarious.

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pm90
I wonder if this applies to all walnut-like families, such as pecans.

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Bud
We need more studies like this. For instance, I'd like one that reveals that
steak and beer actually have negative calories.

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mikeash
It's true, but only if your steak is well done and your beer is Coors.

