Being obese or overweight in middle age will make people's brains "10 years older" than those of their leaner counterparts, a new research has revealed.

The findings, published on Thursday in the journal Neurobiology of Aging, found changes in the brain structure of overweight people which are normally seen in those far older.

After scanning brains of 473 people aged between 20 and 87 and dividing them into lean and overweight categories, scientists discovered that extra weight would accelerate the loss of the brain's white matter.

The volume of white matter, a tissue of the brain that transmits information between different parts, naturally decreases as people get older.

Scientists then calculated how much that white matter volume related to age across the two groups. They found that an overweight 50-year-old had a comparable white matter volume to a slim 60-year-old person.

"The overall message is that brains basically appear to be 10 years older if you are overweight or obese," said Lisa Ronan, lead author of the study from Cambridge University.

Meanwhile, according to the study, the difference of white matter volume was only found from middle age onwards, suggesting that human brains might be particularly vulnerable during this period of aging.

"Clearly, this must be a starting point for us to explore in more depth the effects of weight, diet and exercise on the brain and memory," said co-author Sadaf Farooqi, professor from the Wellcome Trust-Medical Research Council Institute of Metabolic Science at Cambridge.