Food Fight: Scientists are taking on sodas as the 'cigarettes' of obesity

• Count One: Guilt by association.

Soft drink consumption rose more than 60 percent among adults and more than doubled in kids from 1977-97. The prevalence of obesity roughly doubled in that time. Scientists say these parallel trends are one criterion for proving cause-and-effect.

• Count Two: Physical evidence.

Biologically, the calories from sugar-sweetened beverages are fundamentally different in the body than those from food.

The main sweetener in soda — high-fructose corn syrup — can increase fats in the blood called triglycerides, which raises the risk of heart problems, diabetes and other health woes.

• Count Three: Bad influence on others.

Sugar-sweetened beverages affect the intake of other foods, such as lowering milk consumption. Popkin contends they also may be psychological triggers of poor eating habits and cravings for fast food.

He examined dietary patterns of 9,500 American adults in a federal study from 1999-2002. Those who drank healthier beverages — water, low-fat milk, unsweetened coffee or tea — were more likely to eat vegetables and less likely to eat fast food.

• Count Four: Consistency of evidence.

Many studies of different types link sugary drinks and weight gain or obesity. Some even show a "dose-response" relationship — as consumption rises, so does weight.

Collectively, they meet many criteria for proving cause and effect, Dr. William Dietz, director of nutrition at the federal Centers for Disease Control and Prevention wrote in an editorial accompanying a study in February's Journal of Pediatrics.

http://www.ajc.com/news/content/health/stories/0307dietsoda.html