
How do food manufacturers calculate the calorie count of packaged foods? (2003) - matan_a
http://www.scientificamerican.com/article/how-do-food-manufacturers/
======
alexbock
The obvious next question then is how the protein and carbohydrate content is
measured. That sounds like it would require more difficult analytical methods
than bomb calorimetry and might not be worth the time and expense if it were
not for the fact that those need to be reported separately on the label
anyway.

Brief searching suggests that proteins are measured with a nitrogen content
test and fats are determined by mixing the food with a non-polar solvent to
see how much dissolves. Carbohydrates seem trickier and I haven't found a
great explanation. Water solubility might work once the other components are
removed.

~~~
cma
The protein test was famously faked with melamine in the Chinese dog-food
scandal that killed dogs and resulted in a recall:

[https://en.wikipedia.org/wiki/2007_pet_food_recalls](https://en.wikipedia.org/wiki/2007_pet_food_recalls)

~~~
mysterypie
I was following that case closely back in 2007 because of my pet (thankfully
not affected). An astonishing thing I learned was that practically every brand
of cat food and dog food in North America is/was manufactured by a single
company called Menu Foods in Streetsville, Ontario, Canada.

The pet food "brands" don't have their own factories. They all contract it out
to the same place. A few journalists remarked on this secret fact that came
out because of the recall.

We agonize over which brand is healthier for our cats and dogs, but it's all
an illusion. The majority of US and Canadian pet food is made at one factory
with the same basic animal ingredients, same quality control, same employees,
and the same machines. Maybe they adjust the proportions slightly and tweak
the flavors. Then they slap on different labels like Purina, Iams, Royal
Canin, whatever.

It's saddening to learn that we really don't have as much choice as we think.
I'm much more skeptical and questioning than the average person, and yet I
assumed that the pet food's "brand name" somehow made a difference.

~~~
spoofball
the majority of pet food is meat not fit for human consumption. [1]

if you aren't feeding your pet meat that you eat, it's living on extreme crap.

[1]: [http://www.dogfoodadvisor.com/dog-food-industry-
exposed/unfi...](http://www.dogfoodadvisor.com/dog-food-industry-
exposed/unfit-for-humans-legal-for-dog-food/)

~~~
refurb
My dog will eat other animal feces. His standards for "food" are pretty low.

~~~
spoofball
No one is talking about standards. I'm talking about food that might make your
dog sick or malnourished.

But to each his own.

------
tezza
> 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

~~~
ysleepy
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.

~~~
rhinoceraptor
> 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.

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

------
yodsanklai
> The original method used to determine the number of kcals in a given food
> directly measured the energy it produced.The food was placed in a sealed
> container surrounded by water--an apparatus known as a bomb calorimeter. The
> food was completely burned and the resulting rise in water temperature was
> measured.

I don't think the article addresses the following point. I may be totally
wrong but I suspect the residues of the combustion still contain organic
molecules that could possibly be broken down furthermore by some other process
and release more energy (I believe it's the case with fuel, I remember a
chemistry teacher telling us that burning fuel was terribly inefficient).

Would it be possible that the digestion mechanism is somehow more efficient at
breaking down this molecules and produce more energy than combustion?

~~~
gambiting
Considering how nutritious(for bacteria) our faeces are, I strongly suspect
not. If anything, we know that calories from certain types of food (like nuts)
are not absorbed in 100%, so even though a packet of nuts might say it has 500
kcal, it doesn't mean you will get 500 kcal out of it.

------
lukasm
In Poland it's regulated, you can be off by 15%. My mate did tests in a lab.
All products he picked showed 15% lower kcal value on the packaging.

I pick reduced fat houmous from the fridge. The label says 100g has 256kcal
(18g of fat, 13g of carbs, 8,5g of protein = 248kcal)

~~~
thesimon
And apparently in the US you can be off by whatever you want

[https://www.youtube.com/watch?v=hE2lna5Wxuo](https://www.youtube.com/watch?v=hE2lna5Wxuo)

The video also deals with calorie count in restaurants. The NYC regulation to
require calorie counts directly on the menu really seems like a good idea.
Other than the people already knowing the rough calorie count, who checks the
obscure and difficult tables on the website?

~~~
cperciva
_who checks the obscure and difficult tables_

I'm not sure exactly which tables you're referring to here, but if you mean
tables showing nutritional details beyond the mere number of calories: Being
able to look up how many grams of carbohydrate they're consuming is a
incredibly important for type 1 diabetics.

~~~
thesimon
>I'm not sure exactly which tables you're referring to here,

These

[http://www.bk.com/pdfs/nutrition.pdf](http://www.bk.com/pdfs/nutrition.pdf)

nutrition information tables. The Burger King one actually looks quite
reasonable. Compare this to the German Starbucks one:

[http://globalassets.starbucks.com/assets/4145371584DF4F75A9E...](http://globalassets.starbucks.com/assets/4145371584DF4F75A9E0ADEAF5A388E3.pdf)

I doubt a lot of people would reconsider their choice to order a frappuccino
if they knew it contains as much calories as a Big Mac.

It's good that it's so detailed, but a tl;dr version on the board would be
good. It's not like the average joe opens this on their phone to compare how
many calories each product has.

>Being able to look up how many grams of carbohydrate they're consuming is a
incredibly important for type 1 diabetics.

Valid point

------
ourmandave
Depends on what side of the package you're reading.

On the back label its says calories per serving. On the front they use a
different serving size to make it seem like it's low-cal.

Like popcorn that's 140 cals/serving, but on the front it says 35 cals per
_cup_.

[http://www.foodfacts.com/ci/nutritionfacts/snack-
foods/smart...](http://www.foodfacts.com/ci/nutritionfacts/snack-
foods/smartfood-delight-sea-salt-popcorn-55-oz/92496)

Or a pkg of 2 cupcakes is 380 cals, but they'll say 190 cals per cake (in
small type). It makes you think it's 190 for the pkg of cakes.

~~~
ng12
But they also list servings per package. As someone who relies on this
information out of medical necessity I've never felt it to be that confusing.

The EU/UK, on the other hand, makes it incredibly difficult by listing things
in units of 100g. Nothing like sitting in a dark movie theater trying to
calculate fractions.

~~~
jobigoud
I often find it more convenient actually because often you don't eat "one
serving". Consider breakfast cereals, rice or pastas. Having the per 100g
values allows you to actually compare one item to the next. When I'm the US I
find myself trying to convert back the per serving to per 100g to get back to
known territory.

~~~
anarazel
This.

Not even primarily due to health/nutritional concerns. A lot of the cereals in
the US are way to sweet for my taste. Haven't found a better way to figure out
which isn't other than comparing contained sugar.

------
qq66
This reminded me of a question I've always had... there's always a lot of mass
of the food not accounted for in the Fat/Carbohydrates/Protein/Fiber. For
example, a can of food that weighs 454g net might only have 150g accounted for
in the nutrition facts. What's in the rest of the food, besides water?

~~~
refurb
Probably fiber and water. When they measure fiber, they tend to measure
specific types of fiber. I'm assuming there are a lot of undigestible things
in food that don't fall into the neat categories.

~~~
niels_olson
What's funny to me is that "fiber" is just ripped up plant cell walls and
interstitial material, which is virtually all carbohydrate. it's just that it
doesn't all get truly digested.

------
silviogutierrez
There are foods on which the standard processes don't accurately measure
energy content. Or at least, certain manufacturers tell us that. Not sure if
to believe them or not.

Example: Quest bars. Their syrup would typically show 4 kcal per gram, but is
actually closer to 2. Supposedly. That's how a bar can have so few calories
and such good macros.

Ultimately, if you're consistent with tracking your calories and its effect on
your weight, it doesn't matter if the values are off by 20, 30, or 50%. Just
be consistently off by... 50%.

~~~
maxerickson
I'm not sure what the syrup in those bars would be, but most liquid sugar
products have a pretty substantial portion of water by mass.

~~~
silviogutierrez
The original syrup was
[https://en.wikipedia.org/wiki/Isomaltooligosaccharide](https://en.wikipedia.org/wiki/Isomaltooligosaccharide)
. I buy retail for my own recipes, under the brand name VitaFiber.

------
blakesterz
The Gastropod Podcast just had a great episode about measuring calories:

[https://gastropod.com/the-end-of-the-calorie/](https://gastropod.com/the-end-
of-the-calorie/)

"For most of us, the calorie is just a number on the back of the packet or on
the display at the gym. But what is it, exactly? And how did we end up with
this one unit with which to measure our food? Is a calorie the same no matter
what type of food it comes from? And is one calorie for you exactly the same
as one calorie for me? To find out, we visit the special rooms scientists use
to measure how many calories we burn, and the labs where researchers are
discovering that the calorie is broken. And we pose the question: If not the
calorie, then what?"

------
BurningFrog
Cooked food often have much more digestible calories than raw food. Because
the heat breaks down complex molecules and make them easier to digest. This
isn't reflected at all in these measurements.

This is why it's real hard to stay healthy on a raw food diet.

I learned this from this book, which I really recommend:

[https://www.amazon.com/Catching-Fire-Cooking-Made-Human-
eboo...](https://www.amazon.com/Catching-Fire-Cooking-Made-Human-
ebook/dp/B0097D71MQ)

------
jcfrei
I have a related question: Can the calorie count reliably predict the effect
on a persons weight? Or is the amount of carbohydrates and fats much more
important?

~~~
tgb
I think the answer is that it's really hard to study this, since food diets
are hard to control over long periods of times but that current research is
consistent with calorie counts being a good estimator of a person weight
gain/loss. Here's a reasonable summary with some studies you can look at for
the details. [1] But this is certainly an area of ongoing research and the
devil is in the details: does it matter when you eat? [2] Does your gut
microbiome affect it significantly? Genetics? Is there inter-person variation
in how their body adapts to different food? Does
fat/carbohydrates/protein/fiber content affect satiety in a manner that helps
people lose weight in real life situations even if it doesn't matter in a
clinically controlled setting where overeating is impossible?

We might never have full pictures of all these questions.

[1] [http://examine.com/faq/what-should-i-eat-for-weight-
loss/](http://examine.com/faq/what-should-i-eat-for-weight-loss/)

[2] I know specifically that this is currently being tested in some large-
scale, high-cost studies. Which tells me that researchers aren't as confident
as [1] makes it sound like.

~~~
misinformation
I won't link to any studies but regarding [2] (gut microbiome] does affect it
ever so slightly. I'm just stating things from memory now, but I remember
reading that our gut bacteria now is different from 50 years ago in such a way
that a person eating (for example) 2000 calories then, would now have to eat
2200. Made up numbers, but the effect was between 5-20%.

As for your last question (food composition and satiety), tangentially
related, in the literature regarding this it seems as if keto has a lot of
support for weight loss. Not because of the way it affects your metabolism or
gut bacteria, but because it does satiate people more adequately than other
diets it was tested against (regular western, Scandinavian and paleo).

------
jackgavigan
_> ..you can also download the food database to a handheld compUter._

I'm going to start referring to smartphones as "handheld computers".

------
dc2
This is a question that's itched me constantly for over 15 years that I never
bothered to look up. Anyone else?

