Olga Krivokoneva - stock.adobe.com - illustrative purposes only, not the actual person - pictured above is a woman eating yogurt in her kitchen

Our appetites may be regulated by a circuit in our brains that is made up of three types of neurons, according to a new study involving mice. In the mice, just three types of brain cells drove them to eat more or less food.

The three-part circuit works by first having specialized neurons sense certain hormones that signal hunger. They communicate whether an animal is hungry or full.

Then, the neurons control neural activity in another part of the brain, which, in turn, controls a third set of neurons located in the jaw. They direct the movements that are required for chewing.

No conscious thought is needed for the three-part circuit to function -- it is like a reflex. It was detected in mice but has yet to be identified in humans. If humans are found to have it, the discovery could change the way we as a society view obesity.

"The control of how much we eat and when we eat is not so much based on your decision process, it just happens -- it's a simple circuit," said Christin Kosse, a lead author of the study and a research associate at the Rockefeller University in New York.

Obesity has been deemed a chronic disease with various causes, such as genetics. Previously, it was regarded as the result of personal decisions related to eating.

However, the new study further supports the idea that physiological differences are a major contributor to obesity. It also helps connect several theories about hunger.

One of them is called "set point theory," which argues that people have a set point in body weight determined by their genetics and their environment.

According to the theory, the body tries to keep a consistent weight, even if a person eats more or less food than they need.

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