Other times, though, the reason why you're constantly hungry is a mystery. Your appetite appears to defy explanation, and nothing you eat seems to tamp it down—but those hunger pangs have a cause too. Read on to find out what’s behind them and how to fuel up to feel comfortably full. (Related: 13 Things You'll Only Understand If You Are a Perpetually Hungry Human)

Salt Is Stoking Your Appetite

Yes, it makes you thirsty in the short term. But over time, a high intake of salt actually causes you to drink less but eat more, recent research shows. After weeks on a high-salt diet, participants in studies published in The Journal of Clinical Investigation reported being hungrier. Salt triggers the body to conserve water, which it does by producing a compound called urea. That process requires a lot of calories, so it revs up your appetite and can make you feel hungry all the time, the study’s authors explain. Processed food often has hidden sodium, so aim to eat more of the fresh stuff. (That said, your doctor might recommend eating more salt if you have this common condition.)

You Need Veggies at Breakfast

When you start the day with starchy, quick-digesting carbs—like cereal, waffles, or toast—you “wake up” your hunger hormones and make them more active all day, says Brooke Alpert, R.D.N. That’s because these foods cause your blood sugar to spike, leading to a rise in insulin and cortisol (a hormone that promotes fat storage), which makes your blood sugar plummet, so you get hungry again. This up-and-down cycle happens whenever you eat starchy foods, but research shows that it’s most volatile when you wake up with an empty stomach. To keep your blood sugar stable and avoid being hungry all day long, Alpert suggests having a breakfast of protein and low-starch carbs, like eggs and vegetables, and saving bread and grains for lunch and dinner.

You're On Edge

If anxiety and worry are keeping you up at night, the lack of sleep can increase your appetite, Larson-Meyer says. Plus, “stress raises your levels of cortisol, which can stimulate hunger,” she adds. To decompress, try hot yoga. Studies show that working out in heat can prolong the natural appetite-suppressing effect of exercise, while yoga helps you relax. (BTW, here's why you're so hungry on rest days.)

You Eat Too Often

Grazing all day throws your hunger hormones out of whack, says Alpert, the author of The Diet Detox. “When you eat small bites and don’t sit down to real meals, you never feel truly hungry or full,” she says. “Eventually, your appetite cues become muted, and you’re vaguely hungry all the time.”

Instead, eat every four hours or so. Have a meal with protein, fiber, and healthy fat three times a day, and supplement with good-for-you snacks when meals are more than four hours apart. A smart choice: walnuts. Eating them activates an area of the brain that regulates hunger and cravings, a recent study found.

You're Bored

When we’re aimless, we look for something stimulating, like food, says Rachel Herz, Ph.D., the author of Why You Eat What You Eat. And research shows we tend to seek out things like chips and chocolate. “If this sounds familiar, tune in to your body and notice true signs of hunger, like a grumbling stomach,” Herz says. “When you eat, focus on the experience and enjoy it.” (More on that here: Learn How to Eat Mindfully)

The more you do this, the better you’ll get at distinguishing between physical and emotional hunger—and, hopefully, realized that you aren't truly hungry all the time.