Fast-food consumption in the U.S. is on the decline, Bloomberg reports.

The Centers for Disease Control found that U.S. adults consumed an average of 11.3% of their calories from fast food in the period from 2007 through 2010, down from 12.8 % in the 2003 to 2006 period, according to the report.

There are still over 90 million obese Americans, including over 78 million adults and 12.5 million children, noted Bloomberg. According to the CDC, 35.7% of adults were obese in 2009 and 2010. Not surprisingly, obese people are the top consumers in the fast-food arena. 

With Americans eating a bit healthier, investors may have expected to see fast-food stocks decline. Yet, just the opposite occurred.

Shares of McDonald's (MCD) nearly doubled from the beginning of 2007 through 2010, despite the financial crisis. And, the stock has climbed further since then, as it is now up 158% as compared to January 3, 2007 -- the first day of trading that year.

Since Burger King (BKW) went public (again) in June of 2012, its stock has climbed 17%.

Unnamed pizza restaurants were included in the CDC's report, as well, according to Bloomberg. It is safe to assume those included Domino's Pizza and Pizza Hut.

Domino's Pizza (DPZ) dropped 2.5% from 2007 through 2010. However, since then, the Ann Arbor, Michigan pizza chain stock has tripled since the beginning of 2007.

Yum! Brands (YUM), which owns Pizza Hut along with other chains such as KFC and Taco Bell, saw an 81% increase from 2007 through 2010. Since 2010, the Louisville, Kentucky company stock has climbed 150%.

Healthy eating or healthy spending?

The decline in fast-food consumption coincides with the financial crisis. The Dow Jones Industrial Average dropped sharply in late 2008 and early 2009, before embarking on a rocky recovery to its present state. It has yet to return to 2007 levels.

On that note, since the start of the crisis, restaurant patronage has declined, likely due to changes in consumer spending habits. Between 2008 and 2010, restaurant visits declined by over 3% and have leveled off since then, according to Restaurant Industry Trends.

In other words, if and when the economy becomes robust again, Americans may begin to dine out more -- including at fast-food restaurants.

The bottom line

The Bloomberg report should raise an eyebrow for investors with fast-food holdings, but it may be a function of a sluggish economy as opposed to a permanent change in consumer preferences.

Fast-food stocks have performed well, even during the financial crisis. Not to mention, as the pace of life increases for many, the natural inclination will be to rely on speedy meals -- and that's the name of the game in the fast-food business.

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