Compulsion without pleasure, whether provoked by sugar consumption or B-19’ s electrode, seems to be related to a flood of the neurotransmitter dopamine into the middle of the brain, where the mesolimbic dopamine reward system lies. The same neural trigger also fires in the brains of drug abusers and gambling addicts. This mechanism must have evolved as a crude neural-override switch, to lock attention on the pursuit. The power dopamine has over us reflects the evolutionary importance of its mission: It’s there to keep us from starving and ensure that we reproduce…. This system, in other words, is normally vital, allowing the perseverance and focus required for all achievements. But when abused or damaged, it can produce manic, destructive behavior. Anyone who has been unable to tear themselves away from inane Web clicking, or compulsively mined a pint of ice cream for bits of cookie dough long after they have stopped enjoying it, or promised themselves they’d play “just one more level” (this is my particular demon), has felt the grip of dopamine. Interestingly, animal studies show that the brain reacts to sweetness, not by switching off this seeking mechanism, but by further heightening the reaction. In a world where sweetness is rare, it’s logical for sugar to trigger focused seeking. It makes some sense, for instance, for the taste of one ripe berry to elicit gorging before this ephemeral sweetness disappears. But when these sorts of binges are routine— as they can be in a sucrose-drenched world— they cause changes in the brain structure similar to those found in brains altered by heroin.
Complicating all this is the fact that wanting and liking are tangled. Liking seems to be related to endorphins as opposed to dopamine, but almost everything that activates the endorphin-linked pleasure centers also activates the mesolimbic dopamine system. The key difference is that it’s harder to provoke liking than wanting. The liking centers in the brain are much smaller, each about a cubic centimeter, “an archipelago of interacting islands,” Berridge wrote. These islands must be triggered simultaneously to create a feeling of pleasure. Desire is robust. Pleasure is fragile and fleeting. The first taste of sugar provokes genuine pleasure, but the desire to eat more only grows as satisfaction fades. Of course we are talking about the simplest form of pleasure here, associated with sweetness. I would expect that the pleasure that comes from a symphony, or a skyline, or a smile, is even more ephemeral.
Food companies have learned to manipulate this neurochemistry, argues former FDA commissioner David Kessler, in his book, The End of Overeating. Of course, it’s not just sugar that jukes our wanting system into overdrive: Fat and salt can also cue dopamine, and it’s the combination of all three (fat, salt, and sweetness) that triggers the most intense yearning. An overeater, in Kessler’s vision, is like a Manchurian candidate who, instead of killing, has been conditioned to respond to a surge of dopamine with a strong hand-to-mouth reflex.
According to Kessler, food makers— oblivious to the extent that they are controlling their customer’s minds— are simply responding to market pressure to design foods that sell. Kessler describes speaking to a group of executives from some of the world’s largest food corporations. He laid out the science, explaining how their products exploited brain chemistry. When he finished, he wrote, “there was complete silence in the room. Then one executive spoke up. ‘Everything that has made us successful as a company is the problem,’ he said.”
It’s not just the food industry. Marketers and advertising agencies working in all sectors of the economy have cobbled together an empirical understanding of what makes our brains flinch with desire. They might not realize they are practicing neuroscience, but they have developed a Madison Avenue folk knowledge for juicing the mesolimbic reward system. Central to this knowledge is the deliberate confusion of desire and pleasure, so that the thrill of the purchase becomes an end unto itself. Plants invented this form of dopamine marketing in fruit— offering sugar as an advertisement to the tongue, a loss-leader given away in exchange for seed distribution. Capitalism perfected this innovation by stripping the satiating bulk and fiber that came with fruit, and offering pure swad— that alluring sweetness that when consumed only cues greater yearning. The success of this strategy has made it pervasive. We now live in an empty-calorie world, where sugar’s equivalents flash their for-sale phosphorescence from highway signs, smartphones, and television screens. The world for sale is a world reduced to lust and hunger— endless oceans of wanting interrupted by brief atolls of contentment.