Why are some people feel hungry all the time?

Lack of sleep may have a direct effect on how hungry you feel and how much you eat. Short sleep duration has been found to reduce levels of a hormone called leptin, which inhibits hunger, and increases levels of the hormone ghrelin, which stimulates hunger. Stress also causes constant hunger.

After a stressful event, cortisol levels in the blood often remain high for a while, effectively increasing your appetite. Your body thinks you should refuel after all this fighting-or-fleeing. That’s the reason why people with stressful lifestyles quite often feel constantly hungry. Pregnancy and periods also result in constant hunger and cravings.