A new study by Dundee, Strathclyde and Bristol universities has found a link between obesity and poorer academic grades among adolescent girls.
The research was carried out in collaboration with Georgia University in America and measured the academic attainment of almost 6,000 children against their body mass index (BMI).
The results showed that 466 girls classed as obese achieved poorer results aged 11, 13 and 16 years when compared to those of a healthy weight.
The link was less clear among boys, according to the team that led the study, said to be the most comprehensive of its kind.
The researchers said they took into account potentially distorting factors, such as poorer background, IQ and the age the girls began menstruating, but found they did not affect the overall results.