A new study shows that health-related food taxes can help reduce obesity levels, but the tax must be at least 20 percent to have a significant impact on population health.

According to BMJ, a study at the University of Oxford determined that a 20 percent "fat tax" on sugary drinks, along with subsidies on healthy foods such as fruit and vegetables, can lead to a 3.5 percent decrease in American obesity levels. It can also prevent up to 2,700 heart disease deaths a year.

There is an ongoing debate among lawmakers over implementing taxes on unhealthy foods. In 2008, former New York Governor David Paterson proposed a 15 percent "obesity tax" on soft drinks to help close the $15 billion budget gap. In November, voters in Richmond, Calif., will decide whether or not the city becomes the nation's first municipality to tax soda and other sugary beverages in an effort to fight obesity.

According to the Center for Disease Control and Prevention, more than one-third of U.S. adults and 17 percent of children are obese. Since 2000, the number of state's with an obesity prevalence over 30 percent has risen from zero to 12 -- causing national medical costs associated with obesity to reach $147 billion in 2008. Adult obesity rates are expected to approach 42 percent by 2030.

A separate U.S. study found that taxing sugar-sweetened drinks by 35 percent led to a 26 percent decline in sales, BMJ said. The result has the food industry up in arms. Critics within the industry argue that such taxes would be ineffective and unfair, plus sales declines would lead to job loss throughout the industry.

BMJ said some advocate that the tax not just be used as a deterrent or to close budget gaps. The money could also finance treatment for diet related diseases (diabetes) and help "reformulate" the food industry to offer foods without salt, sugar or saturated fats.

Oxford's Oliver Mytton points out that policy makers need to be wary of the negative health effects of such a tax, like "changes in other important nutrients and compensatory behaviour that may increase energy intake or reduce energy expenditure."

Do you think policy makers should implement a "fat tax?" Leave your comments below.

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