Multiple choice general knowledge science & technology What is leptin? The name of the dude on the Lucky Charms cereal box. The muscle-building protein that helps burn fat. The nutrient in fruit that works in conjuction with fiber. A chemical from fat that tells your brain you are full. Reveal answer Fill a bubble to check yourself D Correct answer Explanation Leptin is a hormone produced by fat cells that signals fullness and energy sufficiency to the brain. It regulates appetite and metabolism by communicating the body's energy storage status, helping maintain long-term energy balance.