"Then the Grinch thought of something he hadn't before! What if Christmas, he thought, doesn't come from a store. What if Christmas...perhaps...means a little bit more!"
–Dr. Seuss, How the Grinch Stole Christmas!
The physical sensation of hunger is related to contractions of the stomach muscles. These contractions—sometimes called hunger pangs once they become severe—are believed to be triggered by high concentrations of the ghrelin hormone. The hormones Peptide YY and Leptin can have an opposite effect on the appetite, causing the sensation of being full. Ghrelin can be released if blood sugar levels get low—a condition that can result from long periods without eating. Stomach contractions from hunger can be especially severe and painful in children and young adults.Hunger pangs can be made worse by irregular meals. People who can't afford to eat more than once a day sometimes refuse one-off additional meals, because if they don't eat at around the same time on the next days, they may suffer extra severe hunger pangs. Older people may feel less violent stomach contractions when they get hungry, but still suffer the secondary effects resulting from low food intake: these include weakness, irritability and decreased concentration. Prolonged lack of adequate nutrition also causes increased susceptibility to disease and reduced ability for the body to self heal.