'Tis the season for pricey salad greens and heirloom tomatoes at the local farmers' market. But even for those who don't run with the foodie set, produce prices have been growing quickly during recent decades, according to data from the Federal Reserve. Meanwhile, less healthy foods like sweets have remained relatively cheap. Together, the two trends are contributing to a fast-growing obesity rate, experts say.
While food prices are growing, they have not diverged much from the broader rate of inflation, according to Fed data. The consumer price index, or CPI, for food has remained close to the CPI for all items since the late 40s, according to Fed data.
(Granted, the CPI for all items includes food, so any big swings in food prices would shift the CPI as well.)
Still, within that category of food, prices have diverged widely. During the last quarter century, the prices for fruits and vegetables have grown away from prices for most other food groups. Cereals and bakery products have also grown quickly in price, though still significantly below the growth in produce prices.
Meanwhile, price growth for meat, fats, and dairy remained relatively tightly bunched and well below growth for fruits and grains. Sugar and sweets saw the least growth.
And it's not just that these prices are diverging from each other; produce prices are outstripping broader CPI growth, while sugar prices haven't grown quite as fast.
There are several reasons for these price patterns. One is the proliferation of cheap sweeteners like high fructose corn syrup, thanks in part to the massive volumes of corn grown in America. For this reason, people like "The Omnivore's Dilemma" author Michael Pollan are outspoken critics of America's farm subsidy programs.
But part of it is also the nature of both producing and selling processed foods versus fruits and vegetables, says one expert.
"I think because of the way that the packaged food industry has grown, they have become more efficient at making more products at lower expense, I think it's enabled those products to become much more prevalent," says Marlene Schwartz, acting director at Yale University's Rudd Center for Food Policy and Obesity, pointing out that processed foods are often "not perishable, and they're made in huge quantities."
Of course, it's not just that prices are driving Americans toward obesity. There are plenty of overweight wealthy Americans, Schwartz notes. Factors like inactivity and large portions also explain why many people of any economic class put on extra weight.
However, the abundance of cheap calories in processed foods indubitably makes for higher obesity rates among low-income populations, says Schwartz.
"The fact that there's such an astonishingly strong relationship between socioeconomic status and poor health, I think most everyone would agree that economics are driving obesity and the associated negative health outcomes," says Schwartz.