CDC study shows that being somewhat "overweight" has at least one positive effect.

I'm not a scientist or a medical professional (so this should not be considered medical advice) but I like to try to find medical studies that back up claims published here and there. The chart below is based on data drawn from a meta-analysis conducted by the CDC, published in the Journal of the American Medical Association (2013 Jan 2), and posted on nih.gov.

Ninety-seven studies were used for analysis, providing a combined sample size of more than 2.88 million individuals and more than 270,000 deaths. The results showed that those who were somewhat "overweight" according to the standard BMI numbers actually had a lower mortality rate -- by 6% -- than those whose BMI would fall into the "healthy" range. There was even a slight advantage for those in the slightly obese range.

Click the image to see it larger.

For those who prefer their data in a paragraph to a chart, here it is. The study looked at mortality rates for four groups of people: those with a BMI of 18.5 to 20 (called "normal weight"), with a BMI of 20-25 ("overweight"), BMI of 25-30 ("obese grade 1"), and BMI over 30 ("obese grade 2"). The data showed a lower mortality rate for the the overweight and grade 1 obese groups, by 4-5%. Grade 2 obesity, however, showed a markedly worse mortality rate: +29%.

How does that shake out in height and pounds? Here are the numbers for some average height women (U.S.):

BMI if you are 5'2"

- "healthy": 110-130 lbs.

- "overweight": 140-160 lbs.

BMI if you are 5'4" 

- "healthy": 110-140 lbs.

- "overweight": 150-170 lbs.

BMI if you are 5'6" 

- "healthy": 120-150 lbs.

- "overweight": 160-180 lbs.

The study didn't look at quality of life issues, so if you were to mine the same data looking for incidence of diabetes, etc. the picture might look very different. But I just thought it was interesting that even up to a BMI (body mass index) of 35, being somewhat overweight actually has a positive effect on mortality over the course of the study.

Let us always remember, however, that the mortality rate over all time for everyone is 100%!  [insert ironic smiley face here]

Source of human images used in BMI graph: http://ygraph.com/bmi

Source of numbers used for average height BMIs: http://www.youngmomsconnect.org/downloads/bmi_chart.pdf

Graph created by Jana Snyder.