
A High-Fat Diet Alters Crucial Aspects of Brain Dopamine Signaling - chegra
http://www.sciencedaily.com/releases/2010/07/100713011053.htm
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yanowitz
It's too hard to see what this means from the information in the article. What
was the protein and carb content? Was it a low-protein diet or low-carb (I'm
guessing low-protein given other study results)? How many rats? Were they
obese to begin with? etc. etc.

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sophacles
So what does this mean? How does this change the motivation for working (for
food etc). Can it be reversed? How does it interact with other dopamine
processing and dopamine producing actvities (e.g. drugs, sex etc)?

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TheEzEzz
Here I was, excited to post a bunch of reasons why this paper doesn't really
support its conclusion, only to find all the comments on HN already well
informed and adequately skeptical.

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gojomo
Dopamine systems are related to motivation, compulsions, and addictions.

It's unclear whether the changes detected by this study would be correlated
with more or less addictive behavior, task-persistence, long-range goal-
seeking, executive function, etc.

But, it suggests ideas for further research about diet and behavior.

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metamemetics
Questions a reader should ask:

What was the percent fat in relation to carbohydrates/protein? From what I've
read read both a low fat (<20%) and extremely high fat (75-80%) are healthier
than a high fat diet (45%).

What type of fat was added to their diets? All fats were not created equal.

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warpwoof
Interesting, but fairly useless article. I have no idea what this means. Maybe
this is a good thing? Fat is satiating and helps you feel full.

Also, a high-fat diet by implication means you've removed either protein or
carbohydrate, if you're holding calories constant. A low carb diet, if low
enough, puts your body in ketosis, and your brain switches from using glycogen
for energy to ketones. For all we know the title could have been "A Low-Carb
Diet Alters Crucial Aspects of Brain Dopamine Signaling."

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jseifer
Further information took a bit to track down but I found it here:
[http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pd...](http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pdf)

The full article is available for purchase here:
[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...](http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WB2-5087F0J-19&_user=10&_coverDate=06%2F30%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d1ecda4fc9cdb9796fbe6992d14607d2)
though I wasn't willing to buy it.

From the abstract:

\--

 _Consumption of a high fat diet affects phasic dopamine release and reuptake
in the nucleus accumbens J.J. CONE 1,∗ , H.A. ROBBINS 2 , J.D. ROITMAN 2 ,
M.F. ROITMAN 1,2 1 Program in Neuroscience, University of Illinois at Chicago,
USA 2 Dept of Psychology, University of Illinois at Chicago, Chicago, IL, USA
The rate of obesity has climbed dramatically over the past several decades as
food high in fat content has become more read- ily accessible. In the US
alone, approximately one third of adults are considered obese. Obesity has
been correlated with changes in the mesolimbic dopamine (DA) system. Human
imaging stud- ies have revealed that DA terminal regions differentially
respond to food depending on body mass index. In animal subjects, high fat
diet exposure reduces motivated behavior and responses to amphetamine. Thus,
high fat diet exposure may lead to obesity, in part, through feed forward
mechanisms that suppress mesolimbic DA signaling. Here, we determined the
effects of different durations of high fat diet exposure on phasic DA release
evoked by electrical stimulation of the ventral tegmental area. Rats were
given ad libi- tum access to either a high fat diet (60% kcal/g from fat; HFD)
or a low fat diet (10% kcal/gm from fat; LFD). After different durations on
the diet (2, 4 or 6 weeks), rats were anesthetized with urethane. Phasic
spikes in DA concentration were evoked once every 2 min by stimulating the VTA
and measured using fast scan cyclic voltam- metry at a carbon fiber
microelectrode in the nucleus accumbens. DA function was assessed by altering
the number, frequency, and intensity of current pulses before and up to 1 h
after cocaine injec- tion. Cocaine caused a dramatic increase in evoked DA in
LFD rats. In contrast, cocaine caused a much smaller increase in evoked DA in
HFD rats. The data were modeled to determine if baseline and cocaine
potentiated differences in evoked DA between LFD and HFD rats were due to
changes in DA release, reuptake or both. The results demonstrate that high fat
diet exposure results in dramatic changes in phasic DA signaling. Given its
established role in reward, rein- forcement and motivation, these changes in
phasic DA signaling likely contribute to further imbalance between energy
intake and energy expenditure.

doi:10.1016/j.appet.2010.04.046_

\--

The abstract still doesn't say what kind of fat it was (saturated, pufas, etc)
only that it was 60% kcal/g for high fat and 10% kcal/g for low fat.

The linked summary also says nothing about how they measured the dopamine
effects which turned out to be anesthetizing the rats, giving them cocaine,
and then measuring their dopamine levels. The study seemed to show that
cocaine caused a dramatic increase in the dopamine levels of the low fat diet
rats and much less of an increase in the high fat diet rats.

As far as I can tell from that abstract:

Low fat diet = much higher dopamine response from cocaine

High fat diet = lower dopamine response from cocaine

So the authors are concluding that the lower response will lead to eating more
fat in order to get the dopamine reward.

Further reading on dopamine:
[http://scienceblogs.com/developingintelligence/2007/02/dopam...](http://scienceblogs.com/developingintelligence/2007/02/dopamine_for_dummies.php)

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terhechte
Reminds me of the Science News Cycle:
[http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e3258297...](http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e32582970b-800wi)
(image)

~~~
endgame
Actual source: <http://www.phdcomics.com/comics/archive.php?comicid=1174>

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lgv
Do rats eat fat in nature? I don't know anything about animal nutrition, but
is this like feeding protein to say, rabbits, which are herbivores?

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SoftwareMaven
Rats are omnivores, eating a nice, balanced diet like us humans. However, even
if they were straight herbivores, they could still find plenty of fats. Nuts
are a significant food source for small mammals and tend to be fairly high in
fat content.

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b0b0b0b
reduced release sounds bad. but reduced reuptake sounds good!

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malkia
I guess that would explain why Cain killed Abel.

Hehe, not really :)

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sofuture
The biggest thing reading 'Good Calories, Bad Calories' did for me, was make
me question every single scientific study in _much_ greater detail. It's
shocking how much niche* scientific research makes it's way into the 'news',
'common knowledge' or even public policy.

I don't mean this as a knock against this specific study -- however, we don't
have enough information to conclude _anything_ about it.

* = where 'niche' implies a strict and specific set of conditions or even assumptions, reducing 'general applicability'

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WilliamLP
The big part of this article that raises my skepticism is that it's talking
about rat studies without mentioning that there are very many well known,
dramatic, and fundamental differences between rat and human metabolisms.

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donaldc
I wish the article would be a little more specific about what _kind_ of fat
they're talking about. Saturated? Polyunsaturated? Raw? Processed?

For example, if they're talking about processed polyunsaturated fat, it's
probably a leap to apply the conclusions to raw butter.

~~~
electromagnetic
It's also contradictory to existing research. They're saying a decrease in
dopamine due to high-fat intake is linked to obesity, however high-sugar diets
are known to increase dopamine release, which increases the bodies demand for
sugars which leads to diabetes _and_ obesity.

If it's a choice between the two then to me it's better to be fat than fat and
diabetic.

You're also correct, polyunsaturated fat behaves wholly different than
monounsaturated, or saturated, or hydrogenated. Even if they all have some
effect, is one less or more dramatic than another?

Finally, is this going to be useful to anyone in planning their diet to
control weight or is it just more utter bunk like 'avoid eating carbs'. If I'm
avoiding carbs and avoiding fat, I'm left eating ultra-lean-ground-beef and
fat-reduced chicken, which means I'm on a ultra-less healthy version of the
Atkins.

Perhaps these diet doctors can simply say: Don't be a fat ass, exercise and
eat a good mixture of protein, fat and carbs because excluding one is quite
probably extremely bad for your health.

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prodigal_erik
To me that sounds like the hedonic treadmill rather than a contradiction. Fat
and sugar increase dopamine, the extra dopamine reduces the number and/or
sensitivity of D2 receptors over time to compensate, and so your baseline
declines until you need that extra dopamine hit just to get back to normal.

And it sounds more useful for designing drug treatment than diet. If your
eating isn't out of control, you don't have much of the problem the article is
about.

~~~
electromagnetic
No fat decreases dopamine, but sugar increases and both cause obesity.
Logically, balancing the two would cause no increase or decrease and should
lead to a balanced weight, yet the researches don't say this they say people
should avoid eating fatty foods or carbohydrate rich foods.

I'd be interested to see whether a balance of protein/fat/carbs in equal 1/3
parts by weight or 1/3 parts by calorific quantity provides the least effect
on our dopamine levels.

I know personally that when I was on a high-fat diet, I lost weight. I've also
lost weight since I switched from margarine to real butter (note: you'd be
surprised how easy it is to clean baked foods when it's real butter, it took
literally 5 seconds to get a bowl spotless with just hot water which normally
took about a minute after being soaked in hot water with detergent in it),
plus my food tastes a lot less like plastic.

I'm sure this has something to do with my working in construction, however
I've never been sugar-sensitive. I literally tackled a bag of brown sugar with
a spoon as a kid and didn't get a sugar rush, while my wife has gotten a sugar
rush off a caramilk bar.

