Scientists have discovered a central hub of brain cells that may put the brakes on a desire to eat, a study in mice shows.
And switching on these neurons can stop feeding immediately, according to the Nature Neurosciences report.
Researchers say the findings may one day contribute to therapies for obesity and anorexia.
Experts say this sheds light on the many complex nerve circuits involved in appetite control.
'Flick a switch'
Scientists from the California Institute of Technology suggest the nerve cells act as a central switchboard, combining and relaying many different messages in the brain to help reduce food intake.
Using laser beams they were able to stimulate the neurons - leading to a complete and immediate stop to food consumption.
Prof David Anderson, lead author of the study told the BBC: "It was incredibly surprising.
"It was like you could just flick a switch and prevent the animals from feeding."
Researchers then used chemicals to mimic a variety of scenarios - including feelings of satiety, malaise, nausea and a bitter taste.
They found the neurons were active in all situations, suggesting they may be integral in the response to many diverse stimuli.
The cells worked rapidly when mice had taken a full meal, indicating they may also play an important role in the prevention of over-eating.
Prof Anderson said: "These cells represent the first well-defined hub that inhibits feeding in the brain.
"It is likely that similar cells exist in the human brain. If this is true and it can be proved they are involved in inhibiting eating in people, they could one day provide pathways for the development of therapies for many different eating disorders."
They say they would next like to investigate how this cluster of cells interacts with other well-known nerve centres involved in the promotion of food intake.
The population of neurons involved in the current research are buried in a region of the brain known as the amygdala - an area which is also associated with emotions such as stress and fear.
Prof Mohammad Hajihosseini, from the University of East Anglia, UK, who was not involved in the research said: "This is a very important contribution.
"The researchers build on previous work and have found another piece of the jigsaw in the long and complex circuitry involved in appetite control in the brain.
"One of the next questions to answer is whether these neurons could be an important link between feeding and emotions."