Experts said the findings from Oxford University and published online by the British Medical Journal, were much more dramatic than had been expected and were extremely worrying.
The team analysed the results of 63 studies involving 49,220 healthy children aged between five and 15 years old.
The studies measured weight and one or more known cardiovascular disease risk factors, such as high blood pressure, high cholesterol and blood glucose levels.
Body mass index is a calculation of weight divided by height squared, with a figure of between 25 and 30 classed as overweight and more than 30 as obese.
Dr Carl Heneghan, reader in evidence-based medicine at the University of Oxford and a co-author on the paper, said: “The relationship between obesity in children and cardiovascular risk factors such as blood pressure was much greater than we anticipated.
“The magnitude of the effect of obesity upon increasing cardiovascular risk in children is deeply worrying in terms of their future risks of heart disease.
“Obesity is one of today’s most visible, yet highly preventable health problems. The good news is these risk factors can readily be reversed with exercise, good diet, and maintaining a health a weight. Based on what we have found policymakers should make the epidemic of obesity in children as a priority for urgent public health action.”
Dr Matthew Thompson, reader in primary health care at the University of Oxford, said: “Being overweight as a child is more than just about appearance – many children’s hearts and blood vessels are already getting damaged when they are overweight or obese.
Source: British Medical Journal