It can be easy to view hunger as a bad thing — and while it’s certainly an inconvenient feeling — it’s as innate as the need to yawn or go to the bathroom. In fact, hunger is a crucial biological signal. To understand this, a refresher of the autonomic nervous system is helpful. The autonomic nervous (ANS) system consists of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). While the SNS controls the body’s response to threats (e.g., the “fight-or-flight” response), the PNS is the body’s counterbalance and returns the body back to a state of calm.

Our bodies want and need to spend some time in “rest and digest” mode for the ANS and SNS to function properly. During this time, blood pressure lowers, heart rate decreases and gastrointestinal peristalsis increases so you can absorb and digest nutrients and produce energy stores for the future.

As a result, you shouldn’t feel the need to eat around the clock. Many people feel their best when eating smaller meals more often. However, if you find yourself feeling hungry all the time it could be due to one of the following reasons:

1.   YOU’RE NOT EATING ENOUGH PROTEIN OR FIBER

We need all of the macronutrients (proteincarbs and fat) for different reasons, and not all calories will have the same impact on satiety. While carbohydrates are great for providing quick energy, protein, fat and fiber are important for sustaining that energy. A study published in Nutrition Journal found high-protein snacks led to reduced hunger and kept participants satiated for longer. It is generally regarded that foods high in protein and fiber are most effective at generating satiety due to the breakdown and release of nutrients from these foods.

2.   YOU’RE NOT EATING ENOUGH

Whether you’re reducing calories for weight loss, have a fast metabolism or are very active, you may feel constantly hungry if you’re not eating enough to sustain your biological needs. True hunger is a sign from the body that it needs more energy to function and it doesn’t always have to be a growling or rumbling stomach. Hunger can also manifest as fatigue, the inability to concentrate, feeling dizzy or always thinking about food. Try tuning into your body’s natural hunger cues and consult with a registered dietician who can help review your diet and lifestyle and come up with a plan to meet your needs.

3.   YOU’RE DISTRACTED WHEN EATING

Given hectic schedules, you might find you’re eating while walking, driving or scrolling on your phone. However, if all of your meals are rushed, the body has a harder time recognizing fullness. In a study comparing distracted eaters to non-distracted ones, the non-distracted participants reported a reduction in their desire to finish their entire plate of food. In contrast, distracted participants maintained a desire to eat everything on their plate, which may be a contributing factor to overeating. Not only can mindful eating help you feel satiated, but it has also been linked to reduced food cravings and emotional eating.

4.   YOU’RE NOT SLEEPING ENOUGH

Sleep plays a significant role in regulating hormones, which may contribute to increased feelings of hunger. Short sleep duration is linked with elevated levels of ghrelin, a hormone that stimulates appetite, and decreased levels of leptin, a satiety hormone. That means when you’re short on sleep you’re more likely to feel hungrier and crave sugary foods. Focus on creating healthy sleep habits including avoiding alcohol and heavy dinners before bed and leaving gadgets like your phone or laptop in another room.