Scientists have discovered the brain circuit that we have to train to avoid overeating.

More than two-thirds of American adults are overweight or obese, and doctors are still searching for the best and healthiest ways to help people get their eating under control.

We now know that weight gain is not purely an issue of self control, but overeating - or under eating - do have key mechanisms in our brains.

And researchers at Rockefeller University believe that they have worked out which ones: by tampering with neurons that control our memories about food, we may be able to retrain our brains and curb cravings.

Researchers at Rockefeller University discovered a group of neurons that tells the brain to resist food when activated in mice, opening the door to a way to 'retrain' bad eating habits

Every year, 45 million Americans go on a diet, spending an estimated $33 billion on products to help them shed the pounds.

But there is no silver bullet for slimming down, and keeping the weight off long-term requires not just a few months of cutting our carbs or sweets, but a whole lifestyle shift.

And that means changing the way you think about your food too.

Even if they don't meet the clinical criteria for an eating disorder, many Americans report having problematic attitudes and feelings toward food.

For example, half of women feel guilty about the foods they eat when they are with friends, and 12 out of 20 feel guilty about what they eat alone, as do half of men.

Our psychology and our eating patterns are deeply linked through the gut brain connection - so much so, in fact, that some researchers are examining diet as a potential therapy for depression and mood disorders.

But the relationship works in the other direction too: how we think and feel changes how we eat.

In animals, scientists have long thought that appetite was a simple process. An animal sees or smells something it can and wants to eat, so it eats it.

Evolutionarily, most of the time it makes sense for both us and animals to eat when food is available.

However, we also have an evolutionary calculus built into our brains for when the energy an risk of getting a meal is greater than the benefit of that meal.

Humans have evolved past this. It's pretty safe for us to go get as much cake as we like, and making or getting a cheeseburger is no more or less dangerous than acquiring a salad.

Overeating isn't good for any species, though, and the tendency that the new study looks to disrupt.

The researchers found that impairing the system that makes us remember meals may actually help us crave food - or at least resist cravings - more.

They discovered that a group of neurons called hD2R tell mice not to eat when they should not eat, despite the presence of food.

Activating these neurons when the mire were walking around areas with plenty of food lying around seemed to, in turn, deactivate the animals' memory for where that food was.

'Mental connections between food and location are important for survival, and the strength of these connections is regulated by how rewarding an experience is,' explained lead study author Dr Estafania Azevedo.

'These cells keep an animal from overeating.

'They appear to make eating less rewarding and, in that sense, are tuning the animal's relationship to food.

'Because hD2R neurons affect an animal's relationship with food, it also ends up affecting these connections.'

Changing this system of connections disrupts memories of food and how rewarding it is, allowing mice - and maybe humans - to undo the way they've been seeing food, and form a new perception.

'Our study shows that brain areas involved in cognitive processing and memory formation affect feeding behavior,' says Azevedo.

'So it is possible that, with training, people may be able to learn to change their relationship to food.'