- Hunger is driven by diet, appetite hormones, and emotional factors, such as stress
- Stress reduces levels of the brain chemical serotonin, and that can make you feel hungry when you aren't
- Eating at a moderate pace prompts the release of hormones that tell your brain "no more"
(CNN)It's one thing to notice an uptick in appetite if you've been training hard at the gym, or if you're pregnant or PMS-ing. But when you always feel like a bottomless pit for no obvious reason, then something's definitely up. "Hunger is the physiological need for calories, water, and salt, and it's driven by a mix of factors, including your diet, appetite hormones, and emotional factors, such as stress," says Maggie Moon, RD, a Los Angeles-based nutritionist and owner of Everyday Healthy Eating. Figuring out why you can't stop shoveling it down is important, because excess hunger can tip you off to a physical or mental health issue—and giving in to that need to feed can send your BMI into dangerously unhealthy territory. These 11 things will help explain why your belly's been growling.