I was among friends the other night, listening to a doctor go off about how health care in this country costs so much because Americans are fat. If she had to see one more obese mother feed her already-overweight eight-year-old child Cheetos for breakfast, this doctor said, she was going to scream. Want to know why we’re a nation of arthritis- and diabetes-prone heart-attack and stroke victims? she asked. Just think about all that extra weight our bodies were never meant to carry around.

I was attracted to this concept of fat-as-the-problem; I like simple explanations. So I was quite happy—well, maybe happy isn’t exactly the right word—to come across some data to back up that doctor’s claim.

The Agency for Healthcare Research and Quality (AHRQ), a division of U.S. Department of Health and Human Services, recently put out this research note (PDF), demonstrating that in recent years health care costs for overweight and obese people have escalated much faster than for the rest of us. This is something to think about, considering that out of 216.8 million American adults, 58.9 million of us are obese (that’s 27%) and 75.7 million of us are overweight (another 35%). Oh, and we’re quickly getting fatter. We added 10 million more obese people just between 2001 and 2006.

The numbers the AHRQ gives are these:

Between 2001 and 2006, average health care expenditure for normal weight people increased from $2,607 to $3,315—a 27% gain.

For overweight people, the average cost rose from $2,792 to $3,636—an increase of 30%.

And for obese people, the average amount paid increased from $3,458 to $5,148—a gain of 49%.

The AHRQ defines all those “weight” categories in terms of body-mass index, but I won’t get into that here. We all probably have an intuitive understanding of normal, overweight and obese.

And now we also all have an understanding of how much those various conditions cost in terms of health care. Though I should point out that the AHRQ’s expenditure amounts are in nominal dollars. The relationship between normal, overweight and obese holds either way, but if you want to know how much more expensive health care is in terms of what else you might buy with that money, you should adjust for inflation. I did that, putting everything into 2006 dollars: costs for normal-weight people have jumped by 11%, for overweight people by 14% and for the obese by 31%.

Barbara!