
The Microbes in Your Gut May Be Making You Fat (2013) - DrScump
http://www.livescience.com/41954-gut-microbes-make-you-fat.html
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louprado
"If you want to stay lean, you'll want bacteria that are not very efficient"

I hope this article isn't suggesting that it is preferable to have less
efficient digestive systems so that we can all eat more. Given the
environmental impact of food production these efficient digestion microbes are
something we should encourage. Maybe they are harmful because of insulin
spikes ? But the article doesn't mention this.

~~~
jobu
That seems to be the suggestion, but I wonder if it's the the wrong
hypothesis.

What if some bacteria have evolved to "hack" the metabolic signals from our
guts (and possibly other mammals)?

They could stimulate ghrelin to make us want more food to feed them. Or slow
down food progress through the gut to give them more time to reproduce.

~~~
CuriouslyC
You're partly right. The primary byproduct of bacterial fermentation is short-
chain fatty acids. These do in fact stimulate the release of peptide YY, which
reduces gastric motility. It is extremely unlikely that the bacteria are the
ones "hacking" us though; short chain fatty acid production is the result of
fairly ubiquitous, low level pathways whereas modulation of hormone release is
a fairly specialized, high level function.

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daenz
When your calories in is greater than your calories out, you gain fat. The
point that the article is making is that one collection of gut bacteria may be
more efficient at extracting calories from the same food than another
collection, resulting in more "calories in."

What is disconcerting is the idea of engineering your gut bacteria to be less
efficient at absorbing calories and nutrients in order to not require self
control about what you give your body in the first place.

~~~
dragonwriter
> When your calories in is greater than your calories out, you gain fat.

Wrong. Calorie surplus is neither necessary for nor a guarantee of fat gain.

When your calories in are greater than your calories out, you gain net energy
content of body mass. If you have very low body fat already, you aren't going
to be able to gain _lean_ body mass without increasing net energy content,
which means a calorie surplus; and a calorie surplus can sometimes, AFAIK, be
beneficial in building lean body mass even if you _haven 't_ already driven
your body fat %age to a very low level.

Conversely, you can gain body fat while losing lean body mass with a calorie
deficit.

> What is disconcerting is the idea of engineering your gut bacteria to be
> less efficient at absorbing calories and nutrients in order to not require
> self control about what you give your body in the first place.

Why is that disconcerting? If excessive efficiency in this one function is
associated with adverse health outcomes, and people with less efficient (than
the level raising concern) gut microbiomes tend toward healthier weights and
better health outcomes, preference for maximum efficiency in this area is a
harmful microoptimization, like optimizing a firm's software development
operations for maximum lines of code produced per day rather than business
functionality delivered.

~~~
maxerickson
A calorie surplus is pretty necessary for a substantial weight gain. Let's
include some control for water retention when measuring weight in the meaning
of substantial there.

You seem to do this a lot, writing some pedantic elaboration on the wording of
a comment while carefully ignoring the thrust of the meaning. Of course
precision is useful to communication, but yeesh.

~~~
dragonwriter
> A calorie surplus is pretty necessary for a substantial weight gain.

Sure, but that still doesn't justify the upthread claim "When your calories in
is greater than your calories out, you gain fat."

You can maintain a calorie surplus and not gain fat, and if you are intending
to gain a substantial quantity of lean body mass, you will need to. (That you
can gain fat, within a certain range, while losing lean body mass on a calorie
deficit was a less important aspect of my response; the key part was that the
claim "moar calories => moar fat" is significantly wrong.

> You seem to do this a lot, writing some pedantic elaboration on the wording
> of a comment while carefully ignoring the thrust of the meaning.

The thrust of the meaning was that calorie surplus/deficit alone controls body
fat. This is fundamentally and critically wrong, because it ignores the fact
that activity patterns and other factors will control whether a calories
surplus (for example) manifests in fat gain (with constant or decreasing
muscle) or muscle gain (with constant or decreasing fat) or both muscle and
fat gain in some ratio.

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shiftpgdn
The ads on this page triggered my antivirus (legitimately). A forewarning for
anyone not running noscript/adblocker.

~~~
zurn
Offtopic: anyone know a tool or service to diagnose pages for Windows malware
for those of us who aren't on Windows?

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MisterBastahrd
"Making you fat."

No, that isn't how obesity works. What you put in your face is directly
responsible for how fat you become. The microbes are just a factor, they
aren't the root cause.

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windexh8er
I'm not sure it's quite that simple. There hasn't been much research around
gut biome, however that's changing. This topic has been coming up much more
recently and I've recently been reading "The Good Gut: Taking Control of Your
Weight, Your Mood, and Your Long-term Health" by two Stanford researchers
(Justin & Erica Sonnenburg). Just the first few chapters expose evidence that
the simple correlation between consumption and static result is simply not
true. The gut biome clearly plays a much more important role that we truly
understand at this point in time.

~~~
MisterBastahrd
It's pretty much that simple. Unless someone has some sort of lymphatic
condition that causes them to retain fluids or an undiagnosed metabolic
syndrome, you aren't gaining weight unless you are consuming more than you are
expending.

That isn't to say that two identical people with two different gut floras
would necessarily gain or lose weight identically while eating the same diet,
but I've yet to see any evidence that an otherwise healthy person eating
maintenance level calories is going to blow up like a balloon simply because
his gut flora is different. A person with a healthy gut flora might be able to
consume more calories without gaining as much weight, and it's important to
understand WHY that is, but the fact remains that if you don't consume any
more than you expend, you aren't going to gain weight (previously mentioned
caveats notwithstanding).

That said, the western diet is horrible for you. Go to any fast food
restaurant and the only fiber you'll get is in the lettuce on your burger.

~~~
dragonwriter
> but I've yet to see any evidence that an otherwise healthy person eating
> maintenance level calories is going to blow up like a balloon simply because
> his gut flora is different.

The whole point of the article here is that there is a line of research which
has established, both in non-human models and human experiments, that
"maintenance level calories" (especially when considering the content of food
that enters the mouth, rather than what gets absorbed) are not a constant
across different gut biomes.

[http://ajcn.nutrition.org/content/94/1/58.full](http://ajcn.nutrition.org/content/94/1/58.full)

[http://www.researchgate.net/profile/Peter_Turnbaugh/publicat...](http://www.researchgate.net/profile/Peter_Turnbaugh/publication/6617716_An_obesity-
associated_gut_microbiome_with_increased_capacity_for_energy_harvest/links/00b7d51adf064f0dc0000000.pdf)

[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601187/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601187/)

[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3974587/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3974587/)

