Unhealthy foods become less popular as their prices increase, a finding that may support surging interest in taxation as a policy to address poor food choice.  Kiyah J. Duffey, from the University of North Carolina at Chapel Hill (North Carolina, USA), and colleagues assessed the dietary habits of 5,115 young adults, ages 18 to 30 years, enrolled in the 20-year long Coronary Artery Risk Development in Young Adults (CARDIA) Study.  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.  Over the 20-year period, a 10% increase in price was associated with a 7% decrease in the amount of calories consumed from soda and a 12% decrease in the amount of calories consumed from pizza. A US$ 1 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 US$ 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% tax on these foods would result in a decline of roughly 56 calories per person per day, equating to a weight loss of approximately 5 pounds per person per year, with corresponding reductions in the risk of obesity-related diseases.