You’re not really hungry but you still accept another piece of pizza or the last helping of dessert. It’s not you. A hormone deficiency in your brain could be causing you to overeat for pleasure.

A Rutgers Robert Wood Johnson Medical School study published in Cell Reports has revealed that the reduction of glucagon like peptide-1 (GLP-1) in the central nervous system of laboratory mice caused them to overeat and consume more high fat food. When the researchers enhanced the hormone in the brains of the mice, the rodents were less interested in fatty foods.

What are GLP-1 peptides? They are small sequences of amino acids that are secreted from cells in the small intestine and the brain. They work as physiological regulators of appetite and food intake – basically they transmit the message that the stomach is full to the brain. Apart from this, they stimulate insulin secretion and inhibit glucagon secretion.

The research team at Rutgers says it’s not clear how the GLP-1 released in the brain contributes to appetite regulation. The absence of GLP-1 may not be the only reason people overeat but this is a significant finding.

The study also reveals that targeting neurons in the mesolimbic dopamine system, a reward circuit in the brain, may be a better way to control overeating and obesity. This would involve targeting a specific section rather than the whole body and would have fewer side effects.

This is the same area of the brain that controls other addictive behaviors such as drug/ alcohol abuse and nicotine addiction, meaning that the study could also help understand how GLP-1 influences motivational behaviors.

The how, why and when we eat are behaviors controlled by the central nervous system. There has to be a reason that people suffer from hedonic hunger – the drive to eat for pleasure instead of to gain energy?

Worldwide, overeating, which leads to obesity, is seen as food addiction, a neuropsychiatric disorder. Researchers say the physiological and motivational factors will lead to a better understanding of modern eating habits, may weed out causes of dysfunctions, and could lead to targeted therapies for treating obesity. Finding out how the central nervous system regulates food intake behavior via GLP-1 signaling may help tackle this health issue.