Let's face it; some really great tasting food is not good for you. Eaten rarely it may cause little harm, but a steady diet of it can lead to problems.

To encourage healthier choices, some have advocated a tax on sugary soft drinks and other food products often linked to obesity. The idea is a controversial one, but new research indicates it might just have the desired effect.

A study published in the Archives of Internal Medicine says adults tend to eat less pizza and drink less soda as the price of these items increases, and their body weight and overall calorie intake also appear to decrease.

"To compensate for food environments where healthful foods tend to cost more, public health professionals and politicians have suggested that foods high in calories, saturated fat or added sugar be subject to added taxes and/or that healthier foods be subsidized," the authors write as background information in the article. "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."

Kiyah J. Duffey, Ph.D., of the University of North Carolina at Chapel Hill, and colleagues assessed the dietary habits of 5,115 young adults, age 18 to 30, beginning in 1985 to 1986 and continuing through 2005 to 2006. Food price data were compiled for the same timeframe. Participants' height, weight and blood levels of glucose and insulin were also collected and a measure of insulin sensitivity was calculated.

Higher prices, lower consumption

Over the 20-year period, a 10-percent increase in price was associated with a seven percent decrease in the amount of calories consumed from soda and a 12 percent decrease in the amount of calories consumed from pizza. A one-dollar increase in the cost of soda or pizza was also associated with a lower overall daily calorie intake, lower body weight and an improved insulin resistance score, and a one-dollar 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.

"In conclusion, our findings suggest that national, state or local policies to alter the price of less healthful foods and beverages may be one possible mechanism for steering U.S. adults toward a more healthful diet," the authors write. "While such policies will not solve the obesity epidemic in its entirety and may face considerable opposition from food manufacturers and sellers, they could prove an important strategy to address over-consumption, help reduce energy intake and potentially aid in weight loss and reduced rates of diabetes among U.S. adults."

There have been a number of proposals to raise taxes on food thought to contribute to obesity. There's been consideration of a tax on fast food in Detroit and the Senate has mulled a levy on soft drinks filled with sugar.