Do Food Prices Predict Body Mass?

August 18, 2011

A new USDA study found that food prices seem to predict body mass. As junk food gets more expensive, body mass decreases.

Food prices may be able to explain the rising rates of childhood and general obesity in our country, according to a recent USDA report.  The report, titled, The Effect of Food and Beverage Prices on Children’s Weights, explores the effect of food prices on children’s Body Mass Index (BMI) using data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 and the Quarterly Food-at-Home Price Database. As a reminder BMI is an approximation used to estimate body fat based on weight and height; body mass index does not take into account body composition (ie muscle mass) and therefore is only an approximation.   
Not surprisingly, the study found that if prices increased 10 percent for soda, starchy vegetables, and sweet snacks, children's BMIs dropped .42 percent. That translates to half of an eight or 10 year-old's normal weight gain for a year. As well as making prices higher for less than healthy foods like soda, the study also found that making healthy foods more affordable had a positive impact on body mass. 
For example, if the price of 100 percent juice decreases 10 percent, BMIs decreased .3 percent. The same process works for low-fat milk (.35 percent decrease) and dark, leafy vegetables (.28 percent decrease). Making those healthy foods easier to buy does wonders for a child's weight, as their parents find them more feasible options. 
Unfortunately as we take a look at food prices over the past 20 years, we see that the price of fresh produce has risen almost exponentially as compared to sodas and the like.
Looks like it’s time to rethink our food subsidies.