Need another reason to encourage your family to avoid the soda dispenser and opt for drinks such as water, ice tea and non-sugary drinks? Three new studies just published in the New England Journal of Medicine shed further light on the link between drinking sugary drinks and obesity.

One of these studies, which was conducted at Harvard, involved the analysis of genetic and dietary data from 33,000 adults who were participants in three longitudinal studies. Each participant was assessed based on the 32 gene variants that are associated with obesity. The researchers then used dietary information that had been reported by the participants to separate participants into four groups. These groups were based on the quantity of sugar-sweetened beverages that were consumed by the participants. One group reported drinking less than one serving per month. Another group drank between 1-4 servings per month. The third group consumed between 2-6 servings per week. The fourth group drank at least one serving per day. The researchers found that participants who had the highest number of gene variants that were related to obesity and who consumed the most sugary beverages were more than twice as likely to become obese as the participants who drank the least amount of these beverages.

The second study, which was out of Boston Children’s Hospital, followed 224 overweight and obese teenagers who, on average, were 15 years of age. Each of these teenagers reported drinking at least 12 ounces of sugary beverages each day.  The teenagers were random assigned to two groups.  One group participated in an intervention program designed to reduce their consumption of sugar-sweetened drinks. This intervention included home deliveries of alternate beverages, including bottled water and non-sugary drinks, monthly motivational phone calls with parents, and three 20-minute visits with the teens during the study. The other group received two $50 supermarket gift cards, but no instruction on what they should purchase. The researchers found that at the end of the year-long study, the group that participated in the intervention program had gained on average one pound, seven ounces while the group that received the gift cards gained three pounds, five ounces. The researchers followed these teens for another year, but did not continue the intervention program. At the end of the second year, their analysis found no difference in weight gain between the two groups. The researchers cannot say for sure why the difference in weight gain disappeared, but hypothesized that the group that previously had participated in the intervention program had returned to drinking sugary beverages.

The third study out of the Netherlands looked at the effect of drinking sugary beverages on 641 school children between the ages of 4-11 who said they regularly consumed sugar-sweetened drinks. The researchers randomly assigned the children to two groups. The first group drank a non-carbonated sugar-sweetened beverage with their school lunch while the other group drank an artificially sweetened beverage. The researchers analyzed the children’s weight after 18 months and found that the group that drank the sugary beverages had gained on average 16 pounds 3 ounces. In comparison, the group that drank the artificially sweetened drinks gained 14 pounds 1 ounce. Interestingly, the researchers for this study point out that American children drink approximately three times as many calories from sugar-sweetened drinks as the amount consumed by the Dutch children during this clinical trial.