Hunger

Hunger is the sensation and motivation to eat driven by energy deficit, encompassing both physiological signals and psychological perception. It is distinct from appetite, which is the desire to eat that can be triggered by sensory cues.

Biologically, hunger arises when energy stores fall and signals are transmitted to the hypothalamus. The stomach releases ghrelin during fasting, stimulating appetite. In the hypothalamus, neurons in the arcuate nucleus expressing neuropeptide Y and agouti-related peptide promote feeding, while pro-opiomelanocortin neurons produce signals that suppress feeding.

Long-term energy balance is influenced by leptin from adipose tissue and insulin, which modulate hypothalamic sensitivity to hunger signals. Other gut hormones such as peptide YY, cholecystokinin, and GLP-1 contribute to satiety after eating. Brain centers including the lateral hypothalamus and ventromedial hypothalamus play historical roles in feeding regulation.

Hunger has biological, psychological, and social dimensions. Acute hunger occurs with a short-term energy deficit; chronic hunger is linked to food insecurity and poverty, leading to undernutrition in vulnerable populations. Hunger is not synonymous with famine, but prolonged hunger can contribute to malnutrition and health problems such as impaired growth, immune function, and cognitive performance.

Management focuses on meeting energy needs through regular access to nutritious food, balanced meals, and addressing underlying causes such as poverty, conflict, and food systems. In clinical contexts, assessment of nutritional status and monitoring of growth and body weight are important, particularly for children and the elderly.