Leptin

Leptin is a hormone produced primarily by fat cells that helps regulate your body's energy balance by signaling to your brain how much fat is stored. When fat stores are sufficient, leptin levels increase, telling your brain to reduce appetite and increase energy expenditure. Conversely, low leptin levels, often during weight loss or fasting, signal hunger and decrease energy use. Leptin plays a key role in maintaining normal body weight and energy balance, but factors like insulin resistance or genetic issues can affect its function, contributing to conditions such as obesity.