It’s hard to ignore hunger, a powerful drive designed to get your attention and keep the body from starving.

Regular meals that fill the stomach and intestines should calm it down, but what if you’re always ravenous for another bite of food, no matter how much you eat?

Hunger is complicated and can have many different triggers, said Dr. Monique Tello, a clinical instructor at Harvard Medical School, practicing physician and director of research and academic affairs for the healthy lifestyle program at Massachusetts General Hospital.

“One is hormonal, so people’s hormones — in particular ghrelin, a gut hormone — can have a stimulating effect on the sensation of hunger and appetite,” Tello, author of “Healthy Habits for Your Heart,” told TODAY.

“Other signals are more psychological, and these are very commonly the trigger for people’s hunger.”

Medical reasons:

First, it’s important to rule out any medical issues. Anybody who is feeling very hungry all of the time and isn’t able to gain weight or is losing weight should see a doctor, Tello said.

Conditions that could cause constant or excessive hunger, also called polyphagia, include:

Hyperthyroidism: When the thyroid is overactive, a person’s body and metabolism are “all revved up,” Tello noted. Besides being hungry, patients feel jittery, shaky and their heart may be racing.

Diabetes: People with type 1 diabetes lose the ability to make insulin so their body can’t process sugar. “They’re usually telling me: I’m eating and eating, I’m losing weight and I feel terrible,” Tello said. Hunger can also be a symptom of type 2 diabetes, where the body is resistant to insulin.

Damage to the hypothalamus: This part of the brain helps regulate feelings of appetite and satiety. If it’s damaged because of a tumor or head trauma, it can cause uncontrollable hunger and hypothalamic obesity.

Drugs like prednisone — a corticosteroid steroid commonly used as an anti-inflammatory or an immunosuppressant medication — can also increase hunger, said Beth Kitchin, an assistant professor of nutrition at the University of Alabama at Birmingham. So can some hormone therapies for women going through menopause.

Trending stories,celebrity news and all the best of TODAY. This site is protected by recaptcha

She always asks people who complain they’re constantly hungry whether they have started taking any new medicines or changed their doses.

Psychological reasons:

If there isn’t an underlying medical issue, the problem could be in the head.

It’s reasonable to be hungry every three to five hours given how the human digestive system works, Kitchin said. But ever-present food marketing on TV and the constant stream of “food porn” on social media can trigger people to eat often and a lot, both experts noted.

There are also deeply ingrained cultural triggers, like the idea of eating three meals a day plus snacks, Tello said. She hates the “myth of breakfast” — or the notion people have to eat as soon as they wake up.

“I tell patients, ‘The more you eat, the more you want to eat,’” Tello said.

“The more people eat, the larger the stomach gets. The stomach can stretch to accommodate large amounts of food — it’s a distensible organ. Then if it’s empty, it signals hunger. Well, if you’ve got a huge stomach from eating so much so often, the minute your stomach is empty, it’s signaling you to eat and you’re going to eat more.”

A person’s state of mind can play a role, too. Stress can increase levels of ghrelin, research has shown, and being sleep deprived is associated with higher levels of the hunger hormone.

Boredom, anxiety and depression can also send people looking into the refrigerator when they’re not truly hungry.

Lifestyle reasons:

Sometimes the best answer to the question “Why am I always hungry?” is the simplest one: You’re eating too little, exercising too much, or both.

Kitchin often sees it at the beginning of the year when patients go too far with their New Year’s resolutions.

“When people tell me ‘I’m so hungry,’ I look at their food diaries and I can see why they’re hungry. They’re just not eating enough sometimes,” she said.

Solutions:

Don’t make yourself hungrier than you need to be: Limit your exposure to TV and social media. Try to watch your favorite shows without being exposed to advertising, Tello said. She gets her groceries delivered so she can avoid being bombarded by food marketing in the grocery store.

Get honest: Ask yourself, "Am I really hungry? Or am I bored?" Remove yourself from any food temptations if it's the latter. Get help to deal with anxiety or depression rather than self-medicating with food.

Consider intermittent fasting: It can reconnect you with true, biological hunger; make it easier to recognize feeling full; provide daily structure and break the habit of snacking, experts say.

Going without food for a while can help the stomach to shrink, and help people to eat less and experience hunger less, Tello noted.

“I have patients who eat one meal a day and they are fine. I have an aunt who never eats breakfast, she doesn’t feel hungry until lunch time and she’s at a really healthy weight,” Kitchin added.

Feel fuller by adjusting the quality of your diet: Avoid processed carbohydrates and sugars found in foods like white bread, baked goods and cereal. Aim for a satiating diet higher in fiber, protein and healthy fats, Tello advised. Dip carrots into some peanut butter, enjoy a hard-boiled egg or munch on an apple. Such choices will keep you more satisfied, longer.

Foods that naturally contain a lot of water — cucumbers, tomatoes, strawberries, grapes and so on — are more satiating than other options even though they have fewer calories, said Dr. Michael Greger, author of “How Not to Diet: The Groundbreaking Science of Healthy, Permanent Weight Loss.”

These “higher-volume” options take longer to eat, which seems to signal the brain that you’re filling up.

Watch your alcohol intake: Alcohol lowers a person's inhibitions and self-discipline, which can make you eat more.