Taxing junk food could alleviate obesity

Researchers say an 18 percent tax on junk food would result in a loss of 5 pounds of weight per person per year.

Sounds like a no-brainer, but researchers say they now have long-term proof that price and pounds go together like Ben & Jerry's.

Not that everyone believes that extra taxes - like the 2-cents per ounce tax on sugary drinks Philadelphia's mayor has proposed - would solve America's fast-growing weight problem.

The idea of so-called "sin" taxes on junk food items isn't new. In the last year alone, four states have proposed new taxes on candy and sugared soft drinks.

Thirty-three states charge a sales tax on soft drinks, but generally, those taxes are small - the average soda tax rate is five cents on a 12-ounce can that costs $1.

Many health experts believe sugar-sweetened drinks are the largest single source of extra calories Americans consume and that increasing the price results in a corresponding drop in consumption, but little solid research has existed about tax effectiveness as a deterrent.

Enter University of North Carolina at Chapel Hill researchers, who assessed the dietary habits of more than 5,100 adults ages 30 and younger between 1985 and 2006. Food price data was compiled for the same timeframe, along with participant weight, blood glucose and insulin levels.

Over the 20-year timeframe, a 10 percent increase was associated with a 7 percent decrease in the amount of calories consumed from soda and a 12 percent decrease in calories consumed from pizza.

A $1 increase in the cost of soda or pizza was also associated with a lower overall daily caloric intake, lower body weight and an improved insulin resistance score; a $1 increase in the cost of both soda and pizza was associated with even greater changes in these measures.

The researchers estimate that an 18 percent tax on these foods would result in a decline of roughly 56 calories per person per day. These declines would amount to weight loss of approximately 5 pounds per person per year, with corresponding reductions in the risk of obesity-related diseases, they note.

"Such manipulation of food prices has been a mainstay of global agricultural and food policy, used as a means to increase availability of animal foods and basic commodities, but it has not been readily used as a mechanism to promote public health and chronic disease prevention efforts," the researchers wrote.

The study, released Monday, appears in the new issue of the Archives of Internal Medicine published by the American Medical Association. Its results were released the same day as news about another effort aimed at reducing sugar drink consumption among school kids.

The American Beverage Association announced that an agreement with the American Heart Association and the William J. Clinton Foundation has cut shipments of typical, full-calorie soft drinks to schools by 95 percent since 2004.