MONDAY, Jan. 11, 2016 (HealthDay News) -- People who drink sugary beverages every day tend to accumulate more deep belly fat over time, new research suggests.

The study, of over 1,000 adults, found that those who downed at least one sugar-sweetened drink a day had a bigger increase in deep abdominal fat over the next six years.

Researchers said the results are concerning because that type of fat -- known as visceral fat -- surrounds a number of vital organs and is particularly unhealthy.

"Visceral fat is the kind that's closely associated with the risks of type 2 diabetes and heart disease," said Alice Lichtenstein, a spokesperson for the American Heart Association (AHA), who was not involved in the study.

The findings, published Jan. 11 in the journal Circulation, are far from the first to connect sugary drinks to health consequences. Past research has already found that people who consume a lot of sugary drinks tend to have higher rates of diabetes and heart disease.

But the new findings suggest a "mechanism" behind that, said lead researcher Jiantao Ma, of the U.S. National Heart, Lung, and Blood Institute's Framingham Heart Study and Population Sciences Branch.

The study results are based on 1,003 middle-aged adults taking part in a larger study on heart health. The researchers used CT scans to measure each participant's levels of visceral fat, at the study's start and again six years later.

At the outset, 13 percent of the study group said they drank at least one sugar-sweetened beverage every day. And on average, those men and women showed the greatest increase in visceral fat over the next six years.

Compared with people who never had sugary drinks, daily consumers accumulated about 27 percent more visceral fat, the investigators found.

That does not prove that sugary drinks, per se, were the culprit behind the fat gain, Ma said.

The American Beverage Association said in a statement that no one dietary factor causes obesity.

"Heart disease and other obesity-related diseases, such as diabetes, have been shown by science to be caused by a multitude of factors, not by a single beverage or food," the association said in its statement.