How do hunger hormones control appetite?

The answer

Appetite is primarily regulated by two opposing hormones. Ghrelin, produced by the stomach when it is empty, acts as a hunger signal by stimulating appetite centers in the hypothalamus, with levels peaking just before meals and dropping after eating. Leptin, produced by fat cells in proportion to body fat stores, signals satiety and suppresses appetite. In a well-functioning system, these hormones maintain energy balance. However, in obesity, the body can develop leptin resistance, where the brain stops responding to leptin's satiety signal despite high circulating levels, creating a state of persistent hunger. Sleep deprivation disrupts both hormones, increasing ghrelin and decreasing leptin, which explains why sleep-deprived people consume an average of 385 extra calories per day.