Cutting dietary sugar results in heart health improvements in as little as nine days, according to a new study of obese children who cut sweets from their meals.

The findings, published in the journal Atherosclerosis, are based on an analysis of 37 children ages 9 to 18 who were at high risk for heart disease and Type 2 diabetes, The New York Times reports.

The children were given food and drinks totaling the same number of calories, fat, protein, and carbohydrates as their typical diets. But the researchers replaced foods high in added sugars, like pastries and sweetened yogurts, with bagels and pizza. This lowered dietary sugar from 28 percent to 10 percent, and fructose from 12 percent to 4 percent of total calories.

After nine days, the researchers found a 33 percent drop in triglycerides, tied to heart disease; a 49 percent reduction in a protein called apoC-III linked  to high triglyceride levels; and reductions in small, dense LDL cholesterol, a risk factor for heart disease.

“Sugar calories are not like other carbohydrate calories,” said Dr. Robert Lustig, a co-author of the study and professor of pediatrics at Benioff Children’s Hospital at the University of California, San Francisco. “Without changing total carbohydrate, or fat, or protein, we were able to accomplish this enormous improvement in their cardiovascular risk factors,” unrelated to weight loss, he said.