When researchers analyzed the diet, weight and insulin levels of study participants, they found that when prices of fast foods and sodas went up just 10 percent, participants consumed on average 7.1 percent fewer calories from soda and 11.5 percent fewer calories from pizza. That translates to about 56 calories a day less, which corresponds to a reduction of about 3 to 4 pounds a year per person, Popkin said. The participants who found their fast food prices rose also gained less weight and had a lower risk for diabetes based on a test for fasting insulin (HOMA-IR).

Taxation, particularly in the form of an excise tax, could be helpful as such measures were successful in the case of smoking cessation efforts, Popkin said.

"For these fast foods, taxes would represent the most effective way to reduce adult obesity that we have today, based on this research," Popkin said. He also noted that cigarette taxes have been found to have a much larger effect on teenage versus adult smoking and he would expect that fast food taxes on children and teens would similarly have a larger effect than on adults.

SOURCE Archives of Internal Medicine