Science Finally Explains Why We're So Addicted To Junk Food (And It's Bad News)

Put down the M&Ms: Your junk food habit isn't just making you fat — it's making you boring as well.

According to a new study in Frontiers in Psychology, we lose our natural desire for different types of food when we eat unhealthily on a regular basis.

How? Our brains are wired to seek out nutritional variety so we don't eat too much of one thing. But bingeing on high-calorie, heavily processed goods trips up that wiring, significantly limiting the types of food we consume.

Your brain on a donut diet: Everyone overindulges occasionally, whether it was your friend's seven-layer chocolate birthday cake or the bag of chips in your office desk drawer you told yourself was about to go stale. Junk food is undeniably delicious: Food companies spend millions of dollars perfecting the most satisfying amount of crunchiness in a potato chip, and the ideal amount of creaminess in an Oreo.

However, our brains usually recognize when we've overeaten, so that the next time a super rich treat comes around we simply aren't interested. Instead, we crave something different, like a crunchy apple or a bowl of cereal.

But: When we let our occasional junk food habit become a regular diet, we lose our appetite for diverse tastes. Instead of craving a bowl of ice cream one day and preferring a fresh salad the next, we just want the ice cream. 

All. The. Time.

The research: It would be unethical to subject people to experiments that could endanger their health, so the researchers based their findings on studies they ran with mice. The findings can't be directly extrapolated to humans, but they are a helpful means of gauging what's going on.

The scientists taught young male rodents to associate different sounds with the presence of a sweetened beverage. One group of mice, who stuck mostly to a normal, healthy diet, stopped responding to cues for the beverage when they had recently overindulged in something else with that flavor. 

But the mice who were put on a junk-food diet and fed foods like cookies and dumplings for two weeks kept coming back to the sweetened beverage, regardless of how much they'd recently overeaten.

Why it matters: Nearly 70% of Americans are overweight; many of them are children. Worse still, close to 1 in 5 adolescents aged 12-19 and kids aged 6-11 in the United States is obese. The problem is overwhelmingly concentrated amongst the poorest Americans, many of whom lack access to healthy, fresh food.

Thankfully, there's a convenient way to avoid this: Stick to a diverse diet. 

Even if you don't have access to fresh kale from the farmer's market, you can eat a variety of foods each day. Snack on what you crave when you want it but stop when you're full. Mix up what you consume — snack on different kinds of food, from nuts to fruits and veggies, and make mealtimes an opportunity to try new recipes. Roast chicken one day, grill fish the next.

Your body will thank you.