Overweight children show heart disease risk factors from as early as the age of 15 or 16, a new study has suggested.
The research is the first of its kind to investigate the link between BMI at ages 9 to 12 and then signs of future heart disease aged 15 to 16.
It showed that children who are overweight or obese by the ages of nine to 12 are more likely to display risk factors - including high blood pressure and high cholesterol - by their mid-teens.
The study, published in the British Medical Journal, investigated blood pressure, glucose and insulin levels, and cholesterol in more than 5,000 children.
At the start of the study, when the youngsters were aged nine to 12, 19% of the sample were overweight and another 5% were obese.
Those who were still overweight when they reached 15 or 16 were found to be more likely to have high blood pressure, high cholesterol and high insulin levels - all risk factors for heart disease.
At this age, 29% of the population had high systolic blood pressure (pressure exerted when the heart beats) and 3% had high diastolic blood pressure (pressure between heart beats).
But the risk was found to be reduced in the youngsters who lost weight before they reached 15 or 16, particularly if they were girls.
Researchers said: “Girls who favourably alter their overweight status between childhood and adolescence have cardiovascular risk profiles broadly similar to those who were normal weight at both time points.”
But they found that boys who change from overweight to normal show risk factor profiles intermediate between the normal at both ages and overweight at both ages.
All the findings held true even when other factors likely to influence the results were taken into account.
The experts also found that a large waist circumference and high body fat mass were correlated to increased risk, regardless of BMI.