Why people can eat a full meal and still feel hungry

Eating, feeling satisfied, stopping eating and not overeating, all involve quite a dance between the stomach and the brain. And it's the messages from the stomach to the brain that makes us stop eating.

- DR MIRIAM STOPPARD

But this stomach/brain messaging service breaks down in people with obesity. It seems the brain doesn't heed messages from the stomach.

This blunted brain response may explain why it's difficult for some people to lose weight and keep it off,say researchers at Yale University, US.

"We need to find where that point is when the brain starts to lose its capacity to regulate food intake and what determines that switch" says Yale professor of medicine, Mireille Serlie.

Researchers fed glucose or fat directly into the stomach of 28 people identified as lean (BMI 25 or less) and 30 people as obese (BMI 30 or higher). Then they examined brain activity with functional magnetic resonance imaging (fMRI).