Diet soft drinks have long been thought to be a healthier alternative to their sugary counterparts; however, past reports have linked increased incidence of obesity, metabolic syndrome, and diabetes to the frequent intake of diet soft drinks. 

Sharon P. Fowler, MPH, from the University of Texas Health Science Center at San Antonio, presented the results from the San Antonio Longitudinal Study of Aging. In the study, researchers examined the effect of the long-term consumption of diet soft drinks by a population of individuals 65 to 74 years of age (n = 474). 

At baseline, measures of height, weight, and waist circumference were recorded, as was diet soft drink intake. Three additional exams of the study subjects were conducted over an average follow-up of just over 3.5 years (the study was conducted over a 9-year period). 

When the results of these observations were compared with those from subjects who did not drink diet soft drinks, the differences were striking. Overall, consumers of diet soft drinks experienced a 70% greater increase in waist circumference than nonconsumers. Further, among elderly drinkers of 2 or more diet soft drinks per day, mean increases in waist circumference were 5 times greater than those recorded for nonconsumers. 

“These results suggest that — amidst the national drive to reduce consumption of sugar-sweetened drinks — policies that promote the consumption of diet soft drinks may have unintended deleterious effects,” state the study investigators. 

Previous work by Ms. Fowler has evaluated the negative effects of diet drinks (Obesity [Silver Spring]. 2008;16:1894-1900).