Most of us know how inaccurate the BMI is as a measure of fat & health. A 16-year prospective study just released shows that obesity alone does not determine mortality down the road.The study followed 29,533 volunteers from the Cooper Clinic in Dallas over an average of 16.2 years; 6,224 were considered obese; the obese folks were categorized into a 4 point classification system based on fatness-related illnesses – Edmonton Obesity Staging System (EOSS) levels 0-3.
One of the things I did in my former life was to critique scientific articles. I won’t do that in detail here but will point out a few limitations and summarize. Plus, I encourage you to read the results in the abstract plus look at Table 1 to see the EOSS classification system of health that they used rather than BMI and Table 2 to see the characteristics of the participants.
Bottom line: the more obesity-related diseases at the start (for example, diabetes, heart disease, hypertension, sleep apnea, limitations in daily activities, even mental health issues), the higher risk of mortality over follow-up in EOSS groups 2 & 3. Those in the EOSS classes 0 or 1 actually had lower risk for heart deaths. All EOSS categories had higher risk of cancer. (See Figure 1 from the article below for a picture of risk of death at the end of the study.)
The participants were highly educated, White men (sigh), which means this is not representative of most of us. Not all participants were available for follow-up over the entire study, and the length of time the participants were followed varied by group. (For example the normal weight people were followed for an average of 17.6 years, EOSS 0 and 1 for 18.4, EOSS 2 10.2, and EOSS 3 11.9) I don’t see that the authors attempted to account for this statistically. (But I didn’t read it that closely in my attempt to get this on the blog quickly.) Weight or fat measure was not analyzed over time, so fluctuations could have occurred differentially among the groups.
This doesn’t mean stay fat. This lends credence to the saying, “fat and fit” (If you are a wealthy, educated White male living in Texas…) But the cancer risk is hard to ignore. More importantly it provides a measure for other studies to use rather than BMI for measuring risk in fat folks. Also, if I were a practicing doc, I would start incorporating this scale to assess risk and advise patients. (Because BMI sucks so badly.)
A final caveat. Although this study shows increased risk of death among those with more fat-related (my words) conditions, it does not prove that treatment of fatness or the related conditions will decrease the risk of dying or dying from cancer or heart disease. This study does not address that question. But it is always tempting to extrapolate…