The study, commissioned by the National Institutes of Health and published in the obesity journal, found that children had better blood pressure and cholesterol after 10 days, even though their calorie intake was not reduced.
"This study definitively shows that sugar is metabolically harmful not because of its calories or its effects on weight; rather sugar is metabolically harmful because it's sugar," said Robin Lustig of the University of California San Francisco, who led the study.
In the study, 43 children had their dietary sugar intake reduced from 28% to 10% and substituted with starch for 10 days.
Researchers removed foods with added sugar from a group of children’s diets and replaced them with other types of carbohydrates so that their weight and overall calorie intake remained roughly the same.
Researchers noticed an average decrease of cholesterol by 10 points, and blood pressure by five points. Triglycerides, which are fats that contribute to heart disease, fell an average of 33 points.
By the 10th day, participants were noted as having improved metabolic health.
"This paper says we can turn a child’s metabolic health around in 10 days without changing calories and without changing weight," added Lusting. "From a clinical standpoint, from a health care standpoint, that’s very important."
In the above video, Dr. Mark Hyman explained the difference between complex sugars that can be good for children's health such as fibre, and those contributing to the obesity epidemic.
The study results very much fit in with Jamie Oliver's notorious campaign to reduce the sugar intake children have in their diets.
The 40-year-old chef has recently urged David Cameron to be "bold and brave" about taxing sugar products has made his mission to reduce the amount of sugar kids eat in his progamme 'Sugar Rush'.
Last month the healthy-food campaigner said the "ball is firmly in the Government's court" after a Public Health England (PHE) report suggested a levy of up to 20% would cut sugar consumption.
Oliver praised the study and urged ministers to tackle the obesity crisis "like parents, not politicians".
But the 40-year-old admitted his children do have sweets on the weekend.
"The kids get a little bag - you don't get many sweets for 50p," Oliver, dad to Poppy Honey, 13, Daisy Boo, 12, Petal Blossom, six, and Buddy Bear, five, told The Sunday Times food magazine.
"I don't want to be a Nazi about it. It's about getting it right most of the time - and most is an important word," he added.