The Centers for Disease Control (CDC) estimates that more than a third of U.S. adults are obese, driving a number of the leading causes of preventable death, including heart disease, Type 2 diabetes, stroke and certain types of cancer. In addition to lack of proper physical activity and higher calorie intake of less nutrient dense foods, nutritionists have long suspected a causal relationship between the overconsumption of sugary beverages and weight gain. Now, three studies published in the New England Journal of Medicine on Friday support this association.

“I know of no other category of food whose elimination can produce weight loss in such a short period of time. The most effective single target for an intervention aimed at reducing obesity is sugary beverages,” Dr. David Ludwig from Boston Children’s Hospital told Reuters Health.

Lu Qi, Ph.D, of the Department of Nutrition at Harvard School of Public Health, led a research team that analyzed whether genetic predisposition to obesity is altered by sugar-sweetened beverage consumption. Using data collected from long-term studies involving 33,097 men and women, researchers found that the genetic association with body mass index (BMI) and obesity risk was approximately twice as large among participants with higher intake of sugar-sweetened beverages than among those with lower intake.

Higher intake was defined as one or more servings per day, while those consuming less than one serving per month were classified as having lower intake.

 According to Medical Daily, Qi said the study findings “support legislation designed to reduce sugary drink intake, like New York City’s recent ban on sodas larger than 16 ounces.”

In the second study, 641 children in Denmark between the ages of approximately 5 and 12 were randomly assigned a can per day of a noncaloric, artificially sweetened, noncarbonated beverage or a sugar-containing noncarbonated beverage that were designed to essentially taste and look the same. The children consumed these beverages for 18 months.

Weight, waist circumference and fat mass were measured, adjusted for height changes. Those who were sugar-free gained significantly less weight and body fat. Researchers speculated that reduced consumption of liquid sugars might reduce the insulin spike and thus diminish hunger.

“Children in the United States consume on average almost three times as many calories from sugar-sweetened beverages as the amount provided in our trial,” researchers said in the published findings. “We speculate that decreased consumption of such beverages might reduce the high prevalence of overweight in these children.”

Dr. David Ludwig from Boston Children’s Hospital led the final study assessing the effect of intervention on 224 adolescents consuming at least one serving of sugary drinks or 100 percent fruit juice daily. For one year, sugar-sweetened beverages were substituted with non-caloric beverages, like bottled water and diet drinks at the participants’ homes, and unsweetened water was emphasized.

Overall findings showed a positive association between change in consumption of sugar-sweetened beverages and change in BMI. Non-caloric drinks had an effect on reducing weight in obese children. Intervention also encouraged children to eliminate the consumption of these beverages during the study, and the effects on diet extended a year beyond the study.

“The significant intervention effect for the change in BMI observed at 1 year, together with the findings of [the Dutch study]…provides support for public health guidelines that recommend limiting consumption of sugar-sweetened beverages,” the article on the study findings states.

Earlier this month U.S. Senators Richard Blumenthal (D-CT), Frank R. Lautenberg (D-NJ) and Ron Wyden (D-OR) called for the U.S. Surgeon General to investigate the link between sugary beverages and obesity in this country, as well as analyze policies surrounding these drinks that could help curb the obesity epidemic.

“As America’s waistline has expanded, so too has our access to sugary drinks,” the Senators wrote.  “Doctors and public health experts recommend limiting and reducing the consumption of sugary drinks, especially in children, but kids and adults drink twice the amount of soda that they did three decades ago.”

Nearly 100 national and local health professionals, consumer organizations, scientists and public health departments, including Yale University’s Rudd Center for Food Policy and Obesity, previously called on the Surgeon General in July to issue a report appraising the health effects of sugary drinks and to alert health professionals, government officials, and consumers about the public-health impact of the overconsumption of sugary beverages.

In a letter to Secretary of Health and Human Services Kathleen Sebelius, the groups cited a study that found each additional soft drink consumer per day was associated with a 60 percent increased risk of being overweight in children.

“Research shows that 46 percent of two- and three-year olds consume sugary drinks each day,” they wrote.

Type 2 diabetes, which used to occur primarily in middle-aged and older adults, is now becoming more common among America’s youth. According to the letter, soda and other sugary drinks are the only food or beverage that has been directly linked to obesity and significantly contribute to type 2 diabetes, coronary heart disease, stroke and some cancers, as well as a number of psychosocial problems.

Kelly D. Brownell, director of Yale University’s Rudd Center for Food Policy and Obesity, previously told CBS This Morning that soda is the “single greatest source of added sugar in the American diet. They are completely empty calories – they bring no nutrition at all.”

Brownell notes that Americans consume, on average, 40-gallons of sugary beverages each year.