The Chemistry of Hunger


Hunger is a chemical reaction caused by the hormones Ghrelin and Leptin in the body signaling from organs that they need food or that they have enough food. These signals go into the hypothalamus in the brain which tells the body to stop eating or to eat more. I am interested in knowing why people get hungry and why someone may eat a lot or why someone would not be hungry all the time. Hunger affects me in the same way that it affects almost every animal in the world.

Composition of ...




117-amino acid preproghrelin

28-amino acid ghrelin

The stomach organs

Main Chemicals, Compounds, Components

Ghrelin peptide hormone produced by ghrelinergic cells

28-amino acid ghrelin, 117-amino acid preproghrelin

Leptin A hormone produced mainly by adipocytes

Chemistry's Role

Leptin and Ghrelin are both naturally made in the body. Leptin controls hunger and signals that the body has enough to eat. Ghrelin acts on neurons located in the hypothalamus and increases hunger causing nerve cells. The chemicals from the body in tissue cells and hormones interact with the hypothalamus in the brain to control how much or how little the body needs. ( overproduction of leptin is a major cause of obesity).

Background Research

Hunger is regulated through a series of complex systems in the brain and the body. Cells within the hypothalamus coordinate and control the intake and release of how much food someone needs in their systems. When the hypothalamus is activated they produce the sensation of hunger they do by producing two different kinds of proteins which are called neuropeptide Y and agouti-related peptide. Another nearby set of nerves that greatly inhibit hunger through proteins is cocaine and amphetamine related transcript and melanocyte stimulated hormones.These two sets of nerve cells initiate and send hunger signals to other areas of the hypothalamus. So if you want to eat or not depends on the balance of the activity between these two sets of proteins. The activity of the proteins is mainly controlled by hormones that are circulated in the blood. They come from various tissues in the body including the gut, the fat and the pancreas.


Leptin causes the stomach to

    • Cells in the hypothalamus communicate with other parts of the brain to coordinate the release and intake of chemicals that regulate how much and what you eat.
    • Two important chemicals found in this called ghrelin and leptin communicate with the neurotransmitter called neuropeptide Y which communicates with the brain.

    • Hunger is regulated through nerves in the hypothalamus. They cause hunger through nerves called neuropeptide Y and agouti-related peptide.
    • Mostly controlled by hormones circulating in the blood. They come from tissues in various parts of the body responsible for energy intake and storage including the gut, fat, and the pancreas.

    • Hunger is not a singular motivation. It is the interaction of four different clinically measurable, provably distinct biochemical processes

About the Author

Elishah Reevis jr is a junior attending Billings Senior High School. He enjoys reading, music, and learning new things. He is involved in many clubs including STEM, Interact, BPA, and Senior Advocates. He is interested in the field of Psychiatry, but is also interested in humanitarian relief efforts in third world countries.