A report out today had a lot of us scratching our heads, when it said that about 630,000 people in the U.S. were diagnosed with a cancer associated with overweight and obesity in 2014.

That sounds awfully high, we thought.

It went on to say more than half, 55 percent of all cancers diagnosed in women and about one in four, 24 percent of those diagnosed in men are associated with overweight and obesity.

Now you got our attention.

We asked Farhad Islami, MD PhD, strategic director of cancer surveillance research to have a look. And it turns out there was a simple, and important explanation.

“It’s important to note that only a fraction of the cancers included in the calculation in this report are actually caused by excess body weight. For this study, the authors totaled all of the cancers diagnosed in 2014 for 13 types that have been linked to some extent with excess body weight. In other words, the reported number, 631,000 cancer cases representing 40% of all cancers diagnosed, represents all cases among those 13 types, even though not all of those cancers are caused by excess body weight. Many are attributable to other known risk factors, like smoking, while for many others, the cause is unknown. Obesity is more strongly associated with some cancers than others.

Farhad Islami, M.D., Ph.D.

“As far as the actual estimate of the percentage of all cancers associated with obesity: The World Cancer Research Fund estimates that 20% of all cancers in the United States are caused by a combination of excess body weight, physical inactivity, excess alcohol, and poor nutrition. The American Cancer Society is currently doing its own extensive calculation of the numbers and proportions of cancer cases attributable to excess body weight, the results of which will be published soon.”

Update: Two days later, several headlines confirm this effort to highlight a real problem led to widespread misreporting