Price increases in fuel will have an impact on your waistline in a variety of ways, but perhaps not in the positive ways you might imagine. But first, what does the price of gasoline have to do with how much you weigh? It’s simple economics.

Most obviously, the foods that the average American eats are grown, processed and packaged at farther distances from where we eat them than ever before. Out of season fruits and vegetables are shipped half a world away to keep the supermarket shelves stocked year round. Processed foods are manufactured in one central location then shipped. The most common carrier these days is commercial trucking which relies heavily on cheap oil to move those products to market. So as the price of fuel rises, the cost of shipping rises and the price of the food shipped rises accordingly.

Secondly, the impact on food prices is directly related to the ramping up of ethanol production for our fuel supply. Currently, corn is the major source of ethanol in the United States.  Corn is also a major component in almost every food on your kitchen table today. Corn is the first choice in sweetening foods in the form of high-fructose corn syrup because it is sweeter, more stable and less expensive than sugar. Processed foods from soda to breads contain this sweetener in abundance.

Corn is also in milk, eggs, beef, chicken and other “non-processed” foods like them. How? The dairy farmer feeds his milk cows and egg laying hens corn. That angus cow on your plate was raised on corn, as was the chicken in your soup. Not to mention that humans occasionally like to eat the stuff before it’s consumed by other animals in the form of corn on the cob, canned/frozen corn, popped corn, etc.

So we have all of this competing demand for the simple kernel of corn: gasoline refiners, food manufacturers, dairy farmers, ranchers and people (not to say that the folks doing the other jobs aren’t people too – but you get my point). Back to the economics, as demand increases when there is a limited supply, prices rise. In 2005, corn sold in the U.S. for under $2 per bushel. Today, it sells for more than $5 per bushel. That’s a 150% increase in just over 2 years!

This price increase doesn’t affect the food supply evenly however. According to the U.S. Department of Agriculture, the prices of processed foods will increase at a slower pace than the prices of food staples like eggs, dairy, fruits, vegetables, meat and poultry. That’s because there is more margin in the production costs for food processors in which they can absorb the rising cost of corn, than for the farmer or rancher. This means that the more nutritious whole foods will rise in price quicker and higher than the processed foods of lower nutritional quality.

Here’s how these price increases are likely to affect your waistline. Research has shown a correlation between obesity and income. People in lower socio-economic populations tend to eat fewer whole foods and more processed foods – the type of foods that contribute to obesity. So as food prices rise and you have to make a choice about where to spend your dollar, people who have less money to spend will likely spend it on the lower priced processed foods that are high in calories and low in nutrition, thereby fueling the already epidemic rates of obesity in the U.S.

A silver lining on the cloud may be that as fuel prices rise, people may drive less and actually begin walking or riding bicycles. This may offset the increased consumption of processed foods, keeping the obesity trend in check or even help to lower it. One can only hope.