"It is bad for your blood pressure, knocks years off your life and is a strain on your heart. Now scientists have discovered that gaining weight lowers your intelligence," writes Nina Goswami in The Sunday Telegraph. Nina was commenting on a new French study in this month's Neurology journal which claims to have found a link between obesity and the decline in a person's cognitive function.

The research involved 2200 men and women aged between 32 and 62 taking four mental ability tests. Researchers found that people with a Body Mass Index (a measure of body fat) of 20 or less could recall 56 per cent of words in a vocabulary test, while those who were obese, with a BMI of 30 or higher, could remember only 44 per cent.

The fatter subjects also showed a higher rate of cognitive decline when they were retested five years later. Researchers suggested that hormones secreted from fats could have a damaging effect on cerebral cells, resulting in decreased brain function.

Without all details of the study it is hard to determine whether they gathered enough info to prove that weight affects IQ. A vocabulary test can hardly be enough evidence! But the truth is that extra weight can slow a person down in many ways, and eating right along with proper exercise translates to enhanced mental alertness. You don’t need a study to tell you that.