Only some forms of carbohydrates are the true enemy in the battle of the bulge, researchers at the Children’s Hospital in Boston report.

Careful analysis of the diets of mice showed that mice primarily fed carbohydrates that are low in sugar or are broken down slowly lose dramatically more weight than mice fed the same amount of starchy carbohydrates.

The results published in the current issue of the journal Lancet justify a large-scale trial of the so-called low-glycemic-index diet, which also may reduce risk factors for diabetes and cardiovascular disease.

Unlike the popular Atkins diet, the low-glycemic diet allows for eating a high percentage of some carbs — whole grains, vegetables, nuts and most fruits. But refined breads, breakfast cereals and concentrated sugars are no-nos, as they are on Atkins.

Mice fed a diet of 69 percent starchy carbs had 71 percent more body fat and 8 percent less lean body mass than mice on a low-glycemic diet consisting of 69 percent carbohydrates.

“What the study shows is that glycemic index is an independent factor that can have dramatic effects on major chronic diseases plaguing developing nations — obesity, diabetes and heart disease,” said Dr. David Ludwig, author of the research and director of the obesity program at Children’s Hospital.