A report published in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism suggests that more needs to be done to ensure children maintain a healthy weight.
Senior author Dr Nelly Mauras said: "This new study demonstrates that the unhealthy consequences of excess body fat start very early.
"Obesity alone is linked to certain abnormalities in the blood that can predispose individuals to developing cardiovascular disease early in adulthood."
The experts called for earlier intervention to treat obesity in children from as young as seven before signs of metabolic syndrome become apparent.
By 2020, the government aims to reduce the proportion of overweight and obese children to 2000 levels in a bid to be the first major nation to reverse the rising tide of obesity.