Staring at cake could temporarily turn off cravings research finds
Anew study in the journal Nature suggests that simply looking at food could turn off cravings for a short time
Published 28/04/2015 | 09:27
Staying away from sugary and fatty treats might seem like the best way for dieters to resist temptation.
But a new study in the journal Nature suggests that simply looking at food could turn off cravings for a short time.
Scientists in the US discovered there are hunger-sensitive cells in the brain which make snacking virtually irresistible.
They believe that these brain cells, called AGRP neurons, are left over from our hunter-gatherer past when ancient humans needed encouragement to venture into a risky environments looking for food.
However the cells appear to be temporarily satisfied simply knowing that food is present. Studies on mice showed that the neurons stopped firing as soon as food was in sight.
Although scientists say the neurons would switch back on quickly, it could give dieters a small window where cravings stop and they could choose a healthier option.
Dr Scott Sternson at the Howard Hughes Medical Institute’s Janelia Resarch Campus said humans were hard-wired to find dieting difficult.
"We suspect that these neurons are a very old motivational system to force an animal to satisfy its physiological needs. Part of the motivation for seeking food is to shut these neurons off," he said.
To find out how the neurons was communicating hunger pangs, scientists used a tiny microscope to peer inside the brains of mice while they were eating. They found that the AGRP cells were active until the mice had found food.
What was surprising is that mice did not actually have to eat to silence the neurons. Instead, the cells ceased activity as soon as an animal saw food - or even a signal that predicted food.
The scientists warned that the effect is short lived, but they are hoping to find a way to turn the neurons off for a longer period, to eliminate cravings.
“The neurons will not stay off if food is not consumed,” added Dr Sternson, “The cessation of activity of these neurons needs to be sustained to reduce hunger.
“We think that finding ways to reduce the activity of these neurons as people lose weight might be a way to reduce the unpleasant feeling of hunger that develops during a diet.”
Hunger ensures survival by signaling to the body that energy reserves are low and food is needed to avoid starvation. It affects nearly every cell in the body.
While scientists had discovered the brain cells that make eating food feel satisfying, they did not know what caused the feeling of being unpleasantly hungry.
The AGRP neurons sense the low energy reserves, become activated and suppress the activity of other neurons which are responsible for feelings of fullness, or satiety.
In a separate study scientists at Edinburgh University and Harvard discovered a neural network linked to the AGRP neurons which controls both feelings of fullness and hunger.
They believe that triggering the circuit – called MC4R – would both trigger feelings of satiety, while also switching off uncomfortable cravings.
Dr Alastair Garfield, of Edinburgh University said: “Our study now identifies a very specific subset of neurons that are important for promoting a sense of fullness, and also the pleasurable sensation that goes with it.
“The pharmaceutical industry will be interested in drilling down into these cells to see if they can find a ‘drug-able’ target that can be manipulated to artificially induce a sense of fullness and help suppress appetite, along with alleviating the unpleasant sensations of hunger.”
Harvard’s Lowell laboratory has spent the last two decades creating a wiring diagram of the complex neurocircuitry that underscores hunger, feeding and appetite.
"One reason that dieting is so difficult is because of the unpleasant sensation arising from a persistent hunger drive," said Bradford Lowell, Professor of Medicine at Harvard Medical School.
"Our results show that the artificial activation of this particular brain circuit is pleasurable and can reduce feeding in mice, essentially resulting in the same outcome as dieting but without the chronic feeling of hunger."
The study was published in Nature Neuroscience.