Scrape. Scrape. Scrape. Yes…that’s the sound of my spoon scraping the bottom of the Ben & Jerry’s ice cream container…again. I can’t help myself. When I open a fresh pint of S’mores ice cream, I become a woman obsessed. It’s an all out pleasure hunt for another fudge chunk or a fresh vein of marshmallow. When I find a fat trail of graham crackers running through the ice cream, oh, that is my bliss. I’ll follow that trail, scoop by scoop, until there’s nothing left. And then I’m sad.
But interestingly, give me a pint of plain chocolate ice cream, and I’ll take two bites and be done. Okay, my husband would tell you that’s a lie, but I won’t eat the whole container. The pleasure I derive from chunky, gooey ice cream is just so much greater than the little bit of enjoyment I get from the ice cream alone. Why are those yummy chunks having such a big effect on my brain?
The scientific term for my ice cream binge eating is “hedonic food response,” meaning that my brain has an unusual reaction to a relatively simple mix of milk, sugar, and assorted add-ins. My overindulgence in my favorite ice cream is actually not too different from a drug addict’s response to morphine or heroin. Both hedonic food responses and the addict’s reaction to drugs are partly controlled by the nucleus accumbens (NAcc), one of the main pleasure centers in the brain.
When we get a whiff of something we like (sugar, music, whatever), other parts of our brains send the message to the NAcc. The NAcc gleefully responds with an “Oh goody!” and amplifies that message using natural (or endogenous) opioids, a neurochemical that resembles opiate drugs like morphine and heroin. These endogenous opioids produce that “feel good” sensation that comes during a gluttonous food binge.
To reinforce this point with science, animal studies have shown that direct stimulation of the NAcc or chemical activation of its opioid receptors leads rats to like food a whole lot more than they would without the stimulation. In one study, published in The Journal of Neuroscience, microinjection of an opioid receptor-activating drug to the NAcc caused rats to eat four times more food than a control group. And, those rats more greedily licked their lips (a sign of rat pleasure) when given a sugar drink. Ahem…can we also assume that those rats then had a wicked food coma?
So, some foods (such as sugar) are clearly linked to addict-like behavior in research studies, but the reason for my ice cream chunk obsession might be tough to determine since no researcher (that I know of) is feeding Ben & Jerry’s to mice and measuring the neurological response. However, it’s likely that the enjoyable textures (creamy and crunchy) and the novelty of finding something new (oh look- another cookie!) are also stimulating the pleasure centers of my brain. Therefore, my NAcc probably sees sugar plus fat plus nice textures plus novelty and says “OMG!”
It’s funny- I’m realizing now that my NAcc is very similar to my two-year-old. I walked into the living room on Halloween to a little boy with crazy eyes, chocolate and sugar smeared across his face, a lollipop in one hand, and no pants on, exclaiming “Mommy, we got candy in school today!” He then darted off to run laps around our couch. My NAcc doesn’t normally wear pants and can’t run around the couch, but you get the picture.