

The Animals are Also Getting Fat - yummyfajitas
http://marginalrevolution.com/marginalrevolution/2013/08/the-animals-are-also-getting-fat.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+marginalrevolution%2Ffeed+%28Marginal+Revolution%29

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ericb
The quality of most of these comments makes me sad. I see snark, refusal to
consider new hypothesis in light of previously held beliefs, and rejection of
the idea of entertaining other hypothesis (let's dismiss them as speculation).
Here's a hint--coming up with new hypotheses _is_ speculating. _Then_ you
test. As long as you don't hang your hat on the hypothesis as a new truth
without testing it, speculating is great.

Is there some subconscious need to make fat people's fatness a character flaw?
I'm trying to understand the intransigence against considering what looks like
a great area for research. I'm wondering if this is a case of cognitive
dissonance. The reductionist calories in/calories out approach seems
disingenuous to me. If large portions of the population began breathing 10%
more over a long period, I wouldn't assume they were greedy-breathers, I'd
look for a medical cause.

This _is_ an intriguing finding. Particularly that animals on controlled diets
are gaining weight. (even if the control is simply _what_ is available).
Forgetting the reductionist view, hunger is a drive, and depends on a self-
regulating system. If something is interrupting the equilibrium in animals,
either type of food, type of calories, environment (not necessarily the global
environment, it could be local, like room temperature or something else), or
foreign agents, isn't that pretty interesting, especially if it is happening
to animals on controlled diets with exceedingly similar environments?

~~~
jacques_chester
The problem is that extraordinary claims require extraordinary evidence.

There are broadly two possibilities:

1\. Some unknown phenomenon is defying everything we know about physics.
Matter and energy are being created, apparently from nothing. Or perhaps
transmutation is occurring without emitting lethal doses of gamma and X-ray
radiation.

2\. There has been uncontrolled variance due to faulty or incomplete record
keeping, unobserved changes in activity, genetic drift affecting the appetite
and activity of the population, changes in environment affecting the appetite
and activity of the population (eg cage size change, lighting changes,
temperature changes), unannounced changes in food supply composition (the food
is a commercial product) etc etc et bloody cetera.

In human subjects, when placed in controlled situations, weight loss or gain
very closely aligns to the simplest model of calories in - calories out,
modulo fluctuations in water weight and personal variations in digestion and
activity.

Furthermore, when zoomed out to a population level, BMI tracks calories
consumed per capita very closely[1]. The increase in wealthy country
population obesity reflects that food is cheaper, easier to get and more
calorically dense that at any time in history[2].

Calories in/out _is_ reductionist. But it's all you need to control weight.

[1] [http://wholehealthsource.blogspot.com.au/2012/06/calories-
st...](http://wholehealthsource.blogspot.com.au/2012/06/calories-still-
matter.html)

[2]
[http://www.ncbi.nlm.nih.gov/pubmed/19828708](http://www.ncbi.nlm.nih.gov/pubmed/19828708)

~~~
ericb
> 1\. Some unknown phenomenon is defying everything we know about physics.

You have _entirely_ missed the point if you are arguing about physics when
discussing this. It is like stating tornadoes occur because the wind moves
faster.

When one has data a theory doesn't explain, you hypothesize, and re-test.
That's science. Regardless of whether you have convenient correlations like
your 1 and 2, you don't assume those correlations are causation and stop
researching. What you _don 't_ do is dismiss the outlying data and call it a
day.

~~~
jacques_chester
But that's the point: when people or animals are placed under controlled
conditions specifically to measure changes in mass vs caloric balance, it all
averages out as expected. The samples in this study come from a mix of
uncontrolled wild populations living in contact with humans and from captive
populations who were not subject to a long term control.

In science you don't get to declare any old thing you like and then everyone
else has to immediately agree to test it. Everyone else is free to propose
other hypotheses that fit the facts and it is generally accepted that the
simplest hypothesis consistent with the evidence is more likely to be correct.

The concept of a viral or epigenetic effect on either the efficiency of
digestion or the efficiency of metabolism is worth investigating. However it
would require a complicated mechanism to explain how and why it happened
simultaneously across a mix of populations. Another explanation, given that
all these populations are in contact with the human food supply, is that the
human food supply has changed to be more calorifically dense. And, of course,
it may be some combination of the above.

A simple way to examine the mystery would be to look at animal populations in
other countries. If the wild animal populations of places where people are
starving to death are becoming obese, there might be something to it.

~~~
ericb
> But that's the point: when people or animals are placed under controlled
> conditions specifically to measure changes in mass vs caloric balance, it
> all averages out as expected.

No, that's not the point at all. Whether something is causing a greater
appetite is the point.

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hga
Maybe we're all sensing at some low level that the next Ice Age is coming. We
are overdue one....

This hypothesis could be tested in one way by looking to see if whatever is
happening decreases as you get to the tropics. If so its strengthened, if not
it doesn't necessarily say one way or another.

~~~
AsymetricCom
Brazil is fat, India is fat. It's not an Ice Age, haha.

[http://www.theatlantic.com/international/archive/2013/04/bra...](http://www.theatlantic.com/international/archive/2013/04/brazil-
china-and-india-are-fat-and-getting-fatter/274792/)

~~~
hga
Errr, reread what I said. If they weren't fat it would support the hypothesis.
If fat, who knows?

~~~
AsymetricCom
Sorry, you didn't convince me that your proposal is true. It's quite silly.

~~~
ethanbond
I don't think s/he was trying to. Only to throw out an idea.

~~~
hga
And not even mine, I got it from Glenn "Instapundit" Reynolds, can't remember
if he got it from someone else.

Another half test is to wait and see if we _don 't_ have an ice age, that
would be evidence against it, but not absolute if e.g. the global warming
crowd is partly correct.

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hristov
I think this probably has to do with the sugar in our diets. Animals that live
in human environments tend to eat refuse from our food, and our food has been
getting more and more packed with sugar lately.

The explanation about animals having access to more food does not work. In the
wild, if there is more food, you will simply get more rats. Wild animal
populations tend to rise to match their food supply without giving much
opportunity for animals to get fat.

Unfortunately, the sugar explanation does not quite explain the lab rat
observations. It is possible that the lab rat food has been augmented by sugar
without the scientists noticing. AFAIK lab rats tend to be fed commercial food
mix that is purchased from various suppliers.

The other explanation fits the lab rat results much better but it is much
scarier. It is possible that due to GM crops and/or cattle food supplements we
may have released some new hormone in the food supply and/or the water that
makes us and animals fat.

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toble
I don't know what pet food was like in the past, but today it seems to be
dominated by flavoured products made of cereals, rather than meat or offal.

~~~
aestra
Dominated? I just checked my cat's food, and the first ingredient is chicken
and the second is chicken by product, then corn and the list of supplements.
The dominant ingredient is chicken.

~~~
goblin89
Are you sure there's a regulation regarding listed ingredient order for pet
food? And regardless, I bet manufacturers can get away with even more
ingredient list manipulation there than with human food—I might be wrong
though.

~~~
aestra
Yes I am sure there is a regulation regarding ingredent order in pet food.
[http://www.fda.gov/AnimalVeterinary/Products/AnimalFoodFeeds...](http://www.fda.gov/AnimalVeterinary/Products/AnimalFoodFeeds/PetFood/default.htm)

"...and proper listing of all the ingredients in the product in order from
most to least, based on weight."

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pavel_lishin
I wonder what a study of animals not in a human environment would show,
although I wonder how difficult it would be to find such an environment.

~~~
Someone
Not in a human environment would be a challenge, but IMO somewhat double. But
not in a human environment, where we _do_ have historical weight data? Forget
it.

As to the control mice: my hunch would be that 'let the control animals eat at
will' has changed over time. Maybe the diameter of sugar water tubes has
increased slightly?

Certainly, our notion of what constitutes overweight has changed. If you look
at photos of kids in the 1950s, almost all of them look extremely skinny. We
may project that on lab animals, and size the 'eat at will' containers
accordingly ("hm, the control mice get too fat. Let's make it a tiny bit
harder for them too get their food")

Also, chances are that lab animals live at better controlled temperatures.
Possibly, they used to eat less in hot summers because the temperature in
their cages was higher in summer?

Of course, that's speculation, but it is the simplest explanation I can think
of.

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ShabbyDoo
Could changes in artificial lighting affect food consumption? Lab mice, pets,
and people all have been exposed to similar changes in lighting types over
time. Color temperature effects? The 60hz strobing effect of fluorescent
bulbs? Have better lighting technologies resulted in brighter environments?
Have security concerns. etc. lead to light exposure for more hours of the day?

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dkarl
The study authors supply plausible and completely ordinary explanations for
weight gain in each of the populations. Why speculate beyond that? No reason
except that it's "intriguing."

 _Though it is certainly not necessary that there be a single explanation for
all of these population level increases nor even a single explanation for each
individual population, it is intriguing to consider whether there are any
factors that could conceivably account for weight increases in all of these
populations._

In other words, just more fuel for speculation about some alien contaminant, a
pathogen or pollutant, that we can blame for the obesity epidemic. We have all
the explanations for human obesity that we could possibly need, but we
continue to wish for some cause that does not operate through our behavior.

~~~
XXXCombinator
A few ‘obesogenic’ animal viruses discovered so far:
[http://www.virology.ws/2009/01/30/viruses-and-
obesity/](http://www.virology.ws/2009/01/30/viruses-and-obesity/) Also, modern
gut flora could lead to different absorption rates.

------
ShabbyDoo
Could better control of feral cat/dog populations in urban areas explain the
observed increases in rat weights? What if fatter rats are easier and/or more
desirable prey? Why should a cat waste effort chasing after a fast, skinny rat
when a fat one providing more calories is less likely to outrun it?

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X4
Wrong logic, so wrong.. rats eat what? Exactly, they eat our processed foods,
including high fructose corn sirup and other metabolism altering ingredients.
So much hype about animals getting fat? Prove that monkeys of different types
in their unaltered natural habitat become obese or fat, then I'll start
critically listening.

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AsymetricCom
Obvious: There is more food per individual.

Why? Increased productivity of farming. Have you ever seen a modern farm? They
are just as impressive as any modern sky scraper or any other engineering
accomplishment, probably more so for logical reasons. Once you throw in the
logistical side, even more. The technology being used for traveling salesman
problem is fascinating and cutting edge.

In fact, it's well known that there is plenty of food for everyone on Earth,
but the logistics aren't quite up to snuff.. The result is lots of wasted
food. Logistics is not a popular science for career-minded scientists to get
into, because the costs need to stay low, thus they aren't making a lot of
money. But they are well funded and working with the same type of stuff you'd
see in the Oil Industry. They're supporting an entire society with their
contributions. This is part of the reason I hate Monsanto so much, but that
topic is for another thread.

Humans get all the food they need, so they stop forging, same for our pets, so
they stop hunting. So do the rats, so they stop competing. Etc, etc, cascading
down to many species.

~~~
streptomycin
_" Among mice in control groups in the National Toxicology Programme (NTP),
there was a 11.8 per cent increase in body weight per decade from 1982 to 2003
in females coupled with a nearly twofold increase in the odds of obesity. In
males there was a 10.5 per cent increase per decade."

Control mice are typically allowed to feed at will from a controlled diet that
has not varied much over the decades, making obvious explanations less
plausible._

~~~
gus_massa
How do they select the parents of the next generation? At random? Pick the
more healthier (i.e. 0.1% more weight)? It's possible to do artificial
selection by accident.

The only idea I have to solve this problem is to froze some mice embryos and
defrost some of them in 20 years and compare (and some of them in 50 and 100
years).

