10 Reasons Your Body Craves Junk Food

Junk Food
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It’s a feeling you probably know all too well: You go out to eat and suddenly find yourself unable to think about anything but the creamiest pasta or double-bacon whatever. Before leaving home, you planned to eat clean, go easy, or otherwise not indulge—but once you started reading the menu, all bets were off. “Cravings are a natural response to living in a world where high-calorie foods are all around us,” says Susan B. Roberts, Ph.D., professor of nutrition at Tufts University and founder of the online iDiet weight loss program. “They are not inherently bad, but they cause problems because of the world we live in.” Yes, it’s a world that gave birth to the Double Down. Find out what’s driving your cravings so you can stop them before you’re doubled over in a junk-food-induced stupor.

1. Your genes tell you to eat

Yup, you’re hard-wired to want to chow down on burgers, donuts, and chips. Blame evolution: It made your caveman ancestors want to load up on high-calorie buffalo or sabertooth tiger dinner whenever it was available so that they’d survive until the next hunt. Unfortunately, the human genome hasn’t caught up to the fact that hunting now means taking a detour through a drive-through. “Today, we’re surrounded by a sea of high-calorie junk food, and our genes are telling us to eat it all up because that’s what’s there!” Roberts says.

2. You’re not getting enough Zs

Research shows that sleeping less leads to craving more—and not the healthy stuff. A recent study in the Journal of Obesity analyzed people’s brain activity while they looked at various pictures of food after nine hours of shuteye, and then repeated the slideshow after the people slept only four hours. After only four hours, areas of the brain associated with pleasure and reward lit up more when subjects viewed pictures of donuts, pepperoni pizza, and other junk compared to snaps of carrots and yogurt.

“Sleep deprivation negatively affects all systems in the body, leading the body to crave comfort, whether it’s from a cozy blanket or comfort food,” says Franci Cohen, a certified nutritionist, exercise physiologist, and personal trainer in New York City. “It also causes a decline in overall brain function, including the ability to make proper food choices.”

3. One word: Stress

Short-term stress can actually muffle your appetite, but if you’re chronically harried, your body releases cortisol—a main stress hormone—and levels stay elevated, which gives cravings the equivalent of a megaphone. Your body knows that the fat and sugar in certain high-calorie foods tweak its brain chemistry and help you feel better, so that’s what it wants. For example, sugar seems to lower cortisol and quiet stress signals in the hippocampus, according to a recent study in the Journal of Clinical Endocrinology and Metabolism. Meanwhile, carbs can boost calm-inducing serotonin, Cohen says.

4. You feel great!

Does a version of this scenario sound familiar? You get good news at work—a promotion, a killer review, a new client. You’re excited, happy, and confident, and ready to celebrate. And nothing quite says “reward” like highly palatable foods, says Cynthia Bulik, Ph.D., professor of psychiatry and nutrition at the University of North Carolina at Chapel Hill and author of Crave, Binge Control, and other books on binge eating.

Stress and negative emotions ramp up cravings, but the opposite does, too. “Lots of men, especially, say that positive emotions trigger binge eating,” Bulik says. Yep, you can’t win.

5. You need energy—STAT

Your body stores sugar as glycogen, which it needs for energy. If you’re on a low-carb diet and your glycogen reserves are dwindling, the body can crave foods that deliver the fastest-possible hit of energy—quick-digesting carbs like bread, pasta, cookies, muffins, Cohen says. Instead of going super-low-carb or no-carb, swap refined carbs for complex ones like whole grains, beans, and produce.

6. Blame your sweet (or carb) tooth

Eating a lot of junk carbs can send your blood glucose levels on a roller coaster ride, leading to a vicious cycle of craving and caving. Say your stomach is rumbling and you eat a bagel or a bag of Skittles, which your body breaks down in lightening speed. Sugar floods your bloodstream and you get a quick flash of energy—that’s the sugar high—but your body tries to burn through the sugar all at once. Your pancreas pumps out insulin to deal with the influx, and while some of the sugar gets stored for energy, the rest gets stored as fat. Then glucose levels plummet because there’s nothing left in your tank. That’s the sugar low, Cohen says, and it dumps you back where you started: hungry and craving foods that will give you another high.

7. You’re buzzed

The term beer goggles can apply to food, too. People use their cognitive controls to watch what and how much they eat (as they do with other behavior), but booze squelches those controls. The result: “Alcohol disinhibits appetite,” Bulik says. “When you’re sober, you might say to yourself, ‘It’s wise to only have a few chips.’ But when you’re drinking, that could turn into ‘Whatever, let’s party!’” What’s more, new research in the journal Obesity shows that drinking enhances your brain’s response to food smells—it makes you more sensitive to a delectable aroma, which can shift cravings into overdrive.

8. You eat with your eyes and nose, too

Food porn can remind you of just how incredible a particular food tastes and makes you feel. “Pictures can be mouth-watering, and mouth-watering stimulates the desire to eat,” Bulik says. In fact, compared to photos of nonedible items, pics of hamburgers, cookies, and cakes increased hunger by 19% and the desire for sweet and savory treats by 21% and 14%, respectively—plus, they stimulated areas of the brain linked to reward, according to a study from the University of Southern California. As for your sense of smell? “When it comes to cravings, we are often led by our noses,” Bulik says. “Pumping the smell of popcorn into the movie theater is going to stimulate you to buy and eat.”

9. You’re no different than Pavlov’s dogs

If you grew up eating dessert or you make a habit of always grabbing a donut during your 10 a.m. meeting, then chances are high that breaking your routine will have you craving a treat. People can become conditioned to want sweets at certain times, Bulik says. Ditto after long periods of not eating. If you wolf down a candy bar when you’re hungry, it gives your brain a quick hit of sugar. “That sets up a conditioning experience that pairs ‘relief from intense hunger’ with that high-sugar food,” she says. Boom: You’ve just upped the chances that the next time you’re famished, you’d sell your watch for a candy bar.

10. You’re addicted

Eating sugar releases dopamine, the same brain chemical cocaine triggers. Eat enough of it and changes in your brain cause you to get hooked, which can lead to addict-like cravings and even withdrawal, according to a paper in Neuroscience & Biobehavioral Reviews.

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