You’re Stress Eating Because Your Brain Literally Thinks It Isn’t Full Yet

Mice, they’re just like us—they really like fatty foods and sugary drinks. And according to a new study, they want to eat even more of them when they’re stressed out.

Recently, a group of researchers at Australia’s Garvan Institute of Medical Research found that the part of the rodent brain responsible for controlling hunger and fullness essentially logs off when under pressure. Scientists are confident the exact same thing happens in human brains, too.

We’ve long known that stress impacts our food choices—usually in ways harmful to our health. But very little has been understood about what’s actually happening below the surface when we find ourselves ordering Taco Bell or polishing off a sleeve of Oreos before a big deadline. Herbert Herzog, PhD, the lead researcher, says his team found that chronic stress shuts down the brain’s lateral habenula, which is a neural region that prevents overeating in both mice and humans.

The researchers first divided their mischief of mice (yes, that is what you call a bunch of them) into two groups. Both were fed high-fat mouse chow, but one group was exposed to some mild stressors—such as having their bedding replaced with a shallow pool of water—while the other was left alone. That’s when the scientists discovered what was happening in the lateral habenula. Normally, when a mouse is full, this part of the brain “dampens any positive feelings” about the food it’s eating as an effort to prevent overindulging, Herzog says. But in the stressed group, those same neurons were “silent,” allowing reward signals to stay active and encouraging the mice to keep eating.

Next, the scientists let their mice choose between drinking plain water, or water that had been spiked with sugar. The stressed mice on a high-fat diet guzzled three times as much of the sweetened water than those that were on the high-fat diet but unbothered. The findings suggest that stress delivers a kind of one-two punch to the brain: It quiets the brain’s natural response to satiety, leading to non-stop reward signals that make it more enjoyable to eat highly palatable foods—those typically high in sugar, fat, and calories—and creates a preference for those foods in the longer term.

A molecule called Neuropeptide Y (NPY) seems to be the main character in all of these functions. Experts believe the body naturally produces NPY as a way to cope with stress—the molecule has an anxiolytic effect in the brain, meaning it reduces anxiety—but NPY also shuts down the lateral habenula and prompts you to keep eating comfort foods with abandon. The researchers were able to clearly prove this point: When they artificially blocked NPY (with optogenetics, a biological technique that controls neurons), they discovered that stressed mice consumed less comfort food as a result.

Herzog could technically have performed the same study in humans, but it’s not exactly ethical. “People probably don’t like to be remote controlled,” he says. Still, Herzog—who wanted to know why many of us seem to eat foods higher in fat and sugar when we’re stressed—is confident the findings apply to complex human brains as well as tiny rodent ones. That’s because the neural architecture, particularly the lateral habenula and NPY molecule, are virtually identical in humans and mice. “We can safely assume the pathways and control mechanisms are the same, or at least very similar,” says Herzog.

Thanks to this country’s infamous rat race, over half of the American population experiences stress daily, and simply eliminating that feeling altogether is probably not feasible for most of us. (Presumably not for the mice, either.) So, next time you find yourself dissociating and scraping the bottom of the Pringle canister, lick your fingers, remind yourself that your frazzled brain is starving to be soothed…and maybe try meditation.

Source link