I thought this article was very interesting even though the data doesn't prove a direct link. Exploring a Surprising Link Between Obesity and Diet Soda July 24, 2007; Page D1 Do unhealthy people drink diet soda? Does diet soda make people unhealthy? Those are some of the questions raised by a surprising new study that links consumption of soft drinks -- both the sugared and diet variety -- with a higher risk for a range of obesity-related health problems. High consumption of regular soda, which contains about 150 calories a can, has previously been linked with obesity and diabetes in kids and teens, as well as high blood pressure in adults. But the finding that diet-soda drinkers faced similar health risks is unexpected, because the zero-calorie drinks are often touted as a way to help people prevent weight gain and related health problems. The results may simply signal that the diet-soda drinkers in the study were less healthy to start with, and they had turned to sugar-free beverages to help with weight loss or because they had diabetes. The study investigators, who oversee the respected Framingham Heart Study in Massachusetts, noted also that the type of person who drinks diet soda may be more likely to eat less-healthful foods. But they also cited research suggesting that artificially sweetened beverages may affect a person's satiety or cravings for sweets. "There have been suggestions in the literature that diet soda may not be innocuous," says Vasan S. Ramachandran, associate professor at the Boston University School of Medicine and senior investigator on the study. "We have explanations that we offer as theories, but we need additional research." The research was immediately criticized by the soft-drink industry and some nutrition researchers. "There is no plausible physiological mechanism to explain this and causes me to question the accuracy of the methodologies used in this study," says Dean Ornish, clinical professor of medicine at the University of California, San Francisco, and chairman of the PepsiCo Health & Wellness Advisory Board. The new report from the Framingham study compared soft-drink consumption among nearly 9,000 middle-aged men and women. Overall, soda drinkers were at 48% higher risk for metabolic syndrome, a collection of health problems including being overweight, and having blood-sugar levels signaling diabetes risk. The risks of metabolic syndrome were about the same whether the soft drink was sugared or sugar-free. The study authors noted that the research doesn't prove sodas cause health problems. People who consumed one or more sodas a day were: 44% more likely to have metabolic syndrome 31% more likely to be obese 25% more likely to have higher blood sugar 18% more likely to have high blood pressure Barry Popkin, professor of global nutrition at the University of North Carolina's School of Public Health and frequent critic of the soft-drink industry, says he doesn't "put much credence" in the diet-drink findings in the study, which was published in the journal Circulation. He noted those findings included diabetics, who are at higher risk for health problems and more likely to use sugar-free beverages. When diabetics were excluded, the data were weaker, showing only a 16% higher risk for health problems among soda drinkers. Dr. Popkin says other research contradicts the findings, including a study that found overweight people who consumed diet beverages didn't gain weight. The American Beverage Association, which represents soft-drink companies, said it is "scientifically implausible" to suggest diet drinks could cause weight gain or elevated blood pressure. "All of our industry's beverages ... can be part of a healthy way of life when consumed in moderation," said ABA President Susan K. Neely in a statement. But the data on diet soda have been mixed. One previous study showed a link between diet-soda consumption and weight gain in boys. Some research has suggested that artificial sweeteners may "condition" diet-soda drinkers to develop a preference for sweet, higher-calorie foods. Other studies have questioned whether the caramel content of both regular and diet soft drinks may play a role in insulin resistance. Nutritionists say the study should be a wake-up call for soda drinkers, noting that a zero-calorie beverage can't undo the damage of an unhealthful diet.