Americans these days are living big, though not necessarily in a good way. Even as some people in America turn to healthier lifestyles, obesity rates continue to soar upwards.  That's frustrating news not only for doctors, but for transportation engineers as well.

We already covered how obesity was costing the U.S. airline industry $275M USD more a year in fuel use.  But according to Consumer Reports, it's not the only transportation industry to buckle under the America's growing mass.

The publication cites a 2006 study which indicates that for every pound added to the national average passenger weight, 39 million more gallons of fuel are used.  In total, over 1 billion gallons of fuel a year (about 0.7 percent of the nation's total use) can be attributed to fat.

Other studies show that the effect, while small, may be larger than those previous estimates.  Non-profit company Resources for the Future in 2009 showed that between 1999 to 2005 a 10-percent increase in overweight and obese drivers reduced fuel economy of new vehicle demand by 2.5 percent.

The report also comes to the more controversial conclusion that obesity is driving SUV, van, and pickup truck purchases.  It attributes much of the rise in this sector from 16 percent of total sales in the 1970s to over 40 percent today as being the result of passengers seeking cars to deal with their growing size.

Another study, which we previously covered, comes to the conclusion that obese drivers are more likely to be injured during car wrecks despite their extra mass apparently overcoming whatever padding their flab provided.

The Centers for Disease Control and Prevention (CDC) reports that in America obesity rose 1.1 percent from 2007 to 2009 -- meaning that roughly 2.4 million people entered the category for the first time.  Plus the number of states with over 30 percent obesity rates jumped from three to nine.

Consumer Reports suggests both that Americans need to lose weight and that plus-sized crash test dummies need to be implemented to better protect those who haven't lost weight yet.

There's not always an easy answer for obese drivers.  An Edmonton, Alberta Kia dealer last year was forced to inform a woman who purchased a Kia Rio that she might be too heavy for it.  The sedan was pulling towards the left.  The dealership tried to correct it, to no avail, but eventually gave up, realizing the laws of physics were stacked against them; the driver had too much mass.