The delight we feel in eating highly palatable foods, and the spur to take the next bite, result from brain chemicals titled opioids or endorphins. Pleasure really peaks within a brain tract called the nucleus accumbens, at a tiny "hedonic hot spot," which "causes us to really like something." The opioids hitting the hot spot make us feel terrific, and at the same time propel us to keep eating in what can become a vicious cycle -- as long as the supply of food holds out.
That's where David Kessler's The End of Overeating left us at the end of Ch. 7, as Edward Spurlock diaried this Saturday. Welcome to the continuing diary series "Let's Read a WHEE Book Together!" If you're just discovering this diary series, you will find links to previous installments discussing Kessler's book at the bottom of that diary.
But what about when we are not already eating or really in need of food? Why do some of us, at such times, still feel so nagged by the disembodied spirit of some specific delectable? In Ch. 8, "We Are Wired to Focus Attention on the Most Salient Stimuli," Kessler addresses this question.
The answer, as Kessler parses it, involves a different brain chemical, which sparks and sustains motivation: dopamine.
Dopamine has many functions in the brain, including important roles in behavior and cognition, voluntary movement, motivation and reward, inhibition of prolactin production (involved in lactation), sleep, mood, attention, and learning...
...Recent researches suggest that the firing of dopaminergic neurons is a motivational substance as a consequence of reward-anticipation...[R]eduction in dopamine did not reduce the rat's consummatory pleasure, only the desire to...eat.
Dopamine relates to the feeling of anticipation. It endows us with the motivation, energy and focus to pursue a goal in the face of obstacles.
With plenty of dopamine circulating in their brains, for instance, laboratory rats taught themselves engineering, built a flying machine from castoff hardware, and piloted it to Munich for Oktoberfest. Deprived of normal dopamine, the same rats sat around in their jammies watching reruns of "Dobie Gillis" and bothering to eat only when scientists refilled the popcorn bowls at chairside. (Oh, all right -- dopamine-flush rats learned to scramble over a challenging barrier to get a superior reward, while dopamine-depleted rats, Maynard G. Krebs style, settled for a lesser reward that required minimal effort.)
Dopamine's role in overeating...right after this message:
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What dopamine focuses our efforts on is the most salient stimuli,
standing out relative to neighboring items. Saliency detection is considered to be a key attentional mechanism that facilitates learning and survival by enabling organisms to focus their limited perceptual and cognitive resources on the most pertinent subset of the available sensory data.
Or as Kessler puts it, "The release of dopamine in the presence of the most salient stimuli guides an animal to act with appropriate vigor to pursue the greatest reward. The capacity to filter out lesser background 'noise' is essential to that process."
And thanks to past experiences when highly palatable food rewarded us with a whopping shot of opioids, the potential availability of that item -- despite considerable barriers -- stands out to us as very, very salient. In other words, it is thanks to dopamine that a person -- conceiving lustful thoughts of Kettle Chips, Krispy Kreme or Cherry Garcia -- may layer up in boots, parka, watch cap, scarf and Thinsulate gloves at 11:00 p.m. on a January evening and drive 15 miles to the only all-night outlet in town.
In a state of nature, where calorie-rich foods foods are normally difficult to come by, these brain mechanisms tend to optimize survival. (How much dopamine would it take to motivate you to attack a wooly mammoth with only a spear?) But civilization surrounds human beings with rich edible artifacts and opportunities for which nature has not prepared us. Including
Aussie Cheese Fries:
Calories: 2,710
Fat (g): 203
...
Price: $6.99
Calories per $1.00: 388
This “aussie-tizer” features more sodium and more fat than any other item still known to be featured on a menu. It is also offers more calories per $1, than any other food we could find.
Kessler suggests that what he has called "hyperpalatable" foods --larded with sugar, fat and salt -- act on us as a supernormal stimulus,
an exaggerated version of a stimulus to which there is an existing response tendency, or any stimulus that elicits a response more strongly than the stimulus for which it evolved.
For instance, in experiments,
Small songbirds which laid light blue grey-dappled eggs preferred to sit on a bright blue black polka-dotted dummy so large they slid off repeatedly. Territorial male stickleback fish would attack wooden floats with red undersides--attacking them more vigorously than invading male sticklebacks if the underside were redder.
Oystercatchers and greylag geese also preferred biologically out-of-scale eggs, Kessler reports. Male butterflies would ignore females to chase after an artificial lure that flicked its wings at a more rapid pace than any female butterfly.
These skewed preferences did no harm as long as oversize eggs, artificial butterflies and painted model fish did not exist in the environment. Animals that focused their reactions on the strongest stimuli they met in nature were, on the whole, rewarded with survival and reproductive success. On the other hand, those that reacted to weaker stimuli could end up choosing less healthy mates, brooding defective eggs, or wasting energy on a floating leaf instead of a rival. It took human intervention and "supernormal" human artifacts to send their impulses awry.
Artifacts like
The King?
Built for its namesake, Elvis, this burger tops 8 ounces of Certified Angus Beef with three slices of bacon and fried banana slices rolled in cinnamon and sugar, all sitting on a bun covered with creamy peanut butter.
That the prospect of a supernormal food may charge us up with dopamine, and elicit large amounts of human effort, seems supported -- for example -- by the the many recipes found on the web for deep fried candy bars. As proponents explain, these are mainly county-fair food, but county fairs do not happen every weekend. Still, you can duplicate the opioid experience if you haul out the deep-fat fryer:
The candy bars don’t stay solid during the frying—rather, they liquefy into a gooey, chocolatey, caramelly, nutty mass encased in a crisp shell. You can class them up by serving them with raspberry sauce and whipped cream...
or, for the low-calorie option, you can just leave it plain! In either case, evolution has not prepared us for anything like these concentrations of sugar, fat and salt, all in one food item, and they can swamp our attention with their salience. The same biochemically-rooted motivating power just doesn't emanate from the healthier options that may be staring at us right in the face.
Contemplating the whole opioid...supernormal stimulus...salience......selective perception...dopamine.. vigor... focused effort chain also gave this reader a few murky and inchoate thoughts about other facets of human --- even political -- affairs, but to close on-topic, let's wrap up with an overview of the effort involved in hunting a 21st century wooly mammoth -- from a very helpful site called deep-fry.com that thoroughly explains every aspect and application of this potentially tricky cooking technique.
INGREDIENTS:
1 egg
1 cup milk
1 tablespoon vegetable oil
1 cup all-purpose flour
1 teaspoon baking powder
Pinch of salt
Candy bars (Mars, Snickers, Almond Joy, Kit Kat or Twix work well; use mini versions if you wish)
PREPARATION:
- Chill or freeze the candy bars.
- Combine egg, milk and vegetable oil in a cup.
- In a bowl, combine flour, baking powder and salt. Pour the wet ingredients into the dry ingredients and mix well with a wire whisk. Cover and chill for a few minutes while the oil heats.
- Remove batter from the refrigerator and adjust the consistency if necessary. Heat about 4 cups of oil or shortening to 375 degrees F.
- Dip the chilled candy bar in the batter and gently place into the oil. Cook only until the outside is golden. Remove and drain on brown paper. Allow to cool for a minute as the inside can easily burn your mouth.
Now that's ...well, supernormal hardly begins to say it.