What do people binge eat on, what do they lose control of, what do they have such
strong cravings that they struggle to adhere to dietary goals for themselves?
It isn't foods like apples, or carrots, so
you know I know that's not surprising. Kale was not high on the list,
but it was foods like cupcakes, ice cream, so that is really
what we focused on here. And I think you know one of the
reactions I get a lot when I say you know I do
research on food and addiction is "How can you be addicted to food?" Right?
Everybody has to eat what's the abstinence approach you know, starving?
And I think it's important to note that even from the very beginning
we were saying not all foods are created equal, that there's these certain foods
that actually are not beneficial for our long-term health and
survival, those are the same foods that seem to be particularly effective
engaging reward systems in a problematic way.
So I like to think about what we have been doing to our food environment,
and especially the last 30 and 40 years, if you think of the food environment
that we evolved in, food especially high calorie foods were
relatively scarce and the foods at the top of that hedonic
ladder that were really rewarding and reinforcing were foods like fruits and
nuts, that had higher levels of fats and
sugars in them and we are evolutionarily designed
to want to seek out and find those foods
to be motivated to get them, to remember where they are,
because for so much of our existence those foods were scarce
and we needed them to help us survive times of famine
but over time we've gotten really good especially in our industrialized society
at extracting things like fat and sugars and refined carbohydrates,
cheaply and effectively, and so now we have these ingredients that are really,
really rewarding and more potent doses. And we then combine them
into thousands of different food types that are high
in both sugars, fats, salts, food additives I mean just to give you a feel for how
different our food environment is now compared to the food environment that we
evolved in when I started doing this research we noticed
wow there really aren't naturally occurring foods that are high
both in carbohydrates and high in fat. If you think about that you have fruits,
that are higher in sugar but they don't really have a lot of fat,
you have foods that are higher in fat, like nuts and meats but they don't
really have a lot of carbohydrates. Just the fact that the majority of the
foods that we consume today in our food environment
have a combined combination of high levels of fats
and high levels of carbohydrates is a food that is unique
to the reward system of our brains and much more powerful
than anything our brains really evolved to handle.
So the question is have these foods become
so powerful and so potent that at least for some individuals they're capable of
triggering an addictive response? And so when I was first at Yale and
thinking about what do I want to spend my career on what I'm
here now you know what kind of research do I want to do
there was all this really beautiful emerging work that I felt like was
coming together at the same time So again, Mark was referencing the work
from Bart Hoebel's lab, with Nicole Avena taking a lead role
with these animal models finding these really notable parallels between the administration
of sugar and drugs of abuse. So as Mark mentioned with sugar you
could see this binging behavior, this release of dopamine that wouldn't
go down and the way we expect to see with typical eating behavior.
You saw withdrawal being able to be precipitated by the administration of
drugs that we usually use in drugs of abuse. We saw that
for foods that were high in fats and sugars you could see a
downgrading of the dopamine system that was linked to
behaviors that we really thought of as indicative of drugs of abuse, of
addiction to drugs of abuse. One example coming out of Paul Kinney at
Paul Kinney's lab was that rats that were exposed to
things like bacon and cheeseburger, and M&M's, became so kind of used to that level
of hedonic food reward that even though they would have their
chow that they usually like they usually
ate just fine, they were usually motivated by,
right next to them they'd have their bowl of chow in their cage,
that food, after being exposed to these highly rewarding foods,
no longer did it for them anymore. And even though they could have those calories
they would go out into electrified mazes, getting shocked,
to try and find the M&Ms that were hidden in the maze.
So what this suggests perhaps is that exposure to these foods that are so
potently rewarding seems to potentially cause neural adaptations
and our reward and motivation systems in the brain where
more naturally occurring foods that we used to like and eat just fine
just can't compete at least in these animal models.
At the same time Nora Volkow's group was
doing some beautiful neural imaging work really showing parallels in
the neural systems that seem to go awry
in the context of obesity, in the context of addiction.
For example Mark talked a lot about those cues driving down the highway,
seeing the golden arches, that in both obesity and addiction these cues can become
really powerful and capable of activating intense dopaminergic responses
that are linked with craving and motivation. There also seems to be
some diminishing capacity in the cognitive control systems of the brain
making people more reactive and more motivated to the cues in their environment,
while simultaneously struggling to kind of put on the brakes.