Are we getting fatter or not?

That's a question that a New England Journal of Medicine article attempts to explore. The piece is headlined "Obesity Prevalence in the United States - Up, Down or Sideways?"

Sideways - as in a larger waist size - one would think. The authors, Susan Yanovski and Jack Yanovski, begin with the cup-of-coffee observation that Americans are continually bombarded with statistics on obesity. "The media are filled with news reports celebrating the possible shrinking of our waistlines or lamenting their ongoing expansion."

The authors observe that some recent studies suggest U.S. obesity rates continue to rise at a 1.1% annual rate between 2007 and 2009.

“Such data have led some investigators to suggest that by 2050, an enormous percentage of Americans — perhaps approaching 100% — will be overweight or obese," the report said.

On the other hand, other data show the U.S. obesity prevalence has stabilized. "Results from the CDC’s 2007–2008 National Health and Nutrition Examination Survey (NHANES) suggest that the prevalence of obesity among women (35.5%)2 and children 2 to 19 years of age (16.9%)3 has remained stable over the past 10 years and that the prevalence among men (32.2%) has not changed significantly since 2003," the authors said.

The conflicting observations from various studies have led to confusion about obesity trends, the authors said.

They write:

"Why do the reported rates vary so markedly (see graphs), even though the data all come from government agencies? If obesity rates are stabilizing, why are they doing so? And what do these trends and prevalence rates mean for the current and future health of the U.S. population?"

The authors go into the reasons for the discrepancies in the studies, which include variations because of "self-reported" statistics compared to "actual" recorded statistics.

"Since people often claim to be taller than they are and to weigh less than they actually do, we should not be surprised that obesity prevalence figures based on self-reported heights and weights are considerably lower than those based on measured data," the authors said.

The authors warn against taking premature hope in the perceived stabilization of obesity in America. "Regardless of current trends in obesity prevalence, we are in trouble."

So the next time you hear a statistic that obesity may be declining in the U.S., don't reward yourself with an ice cream sundae. Try a side salad instead.