Reducing sugar consumption can improve health within nine days, according to researchers.
Cutting back, even without reducing overall calorie intake, resulted in lower blood pressure and cholesterol, even in the short time frame.
The study involved 43 obese children aged nine to 18. It looked at the effect of restricting sugar on metabolic syndrome, which involves high blood pressure, high blood glucose levels, excess body fat around the waist and abnormal cholesterol levels, increasing the risk of heart disease, stroke and Type 2 diabetes.
The children were all obese and had at least one other chronic disorder, including high blood pressure. Over nine days, they followed a meal plan that included all snacks and drinks, but restricted sugar intake. Added sugar was banned but fruit was allowed. The diet had the same fat, protein, carbohydrate and calorie levels as their previous diets at home, with the carbohydrate from sugar replaced by foods such as bagels, cereals and pasta. Hot dogs, crisps and pizza from local supermarkets all featured in the diet.
During the study, if the children did lose weight, they were given more of the low-sugar foods to keep weight stable. Overall, the total dietary sugar in the meal plan was reduced from 28 per cent to 10 per cent and fructose from 12 per cent to 4 per cent of total calories.
The results of the study - conducted by Touro University, California and published in the journal Obesity - showed that the new meal plan led to a drop in blood pressure and cholesterol and improved liver function. Fasting blood glucose levels fell by five points while insulin levels were cut by a third, the researchers said.
Dr Robert Lustig, the paper's lead author, said: "This has enormous implications for the food industry, chronic disease, and health care costs. This study 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."
Professor Jean-Marc Schwarz, senior author of the paper, added: "I have never seen results as striking or significant in our human studies."
But UK experts greeted the results with caution. Tracy Parker, heart health dietitian at the British Heart Foundation, said: "This study is interesting, but we need more research to confirm these findings."
Professor Naveed Sattar, of the University of Glasgow, said: "The results are not convincing to me - this is a very small study, and it has not been statistically well controlled."
- Daily Mail