Obese teenagers show signs of brain damage, research has found.

Scans comparing their brains those with adolescents of healthy weight found inflammation in the white matter, which may make it harder for them to control their eating habits. .

MRI scans of the brains showed changes in the areas related to control of emotions, and feelings of reward.

Such changes could encourage excess eating, scientists said,

The findings presented at the Radiological Society of North America meeting in Chicago are based on MRI scans of 12 to 16 year-olds.

Co-author Dr Pamela Bertolazzi, a biomedical scientist at Sao Paulo University in Brazil, said: "Brain changes found in obese adolescents related to important regions responsible for control of appetite, emotions and cognitive functions."

The scans were used to examine the condition of white matter in the 120 participants - 59 of whom were obese and 61 healthy.

Researchers assessed a measure called fractional anisotropy, which correlates with the condition of the brain’s white matter - with less of it indicating damage to the white matter.