Fat people die sooner? Not according to their data!

back to healthread                                Obesity in the studies              back to Obesity page
In this study, a joint effort of the AARP/ NIH.NOW, scientists attempted to "prove" that fat people die sooner.  The news media loved it, of course.

But the proof was flimsy.  None of the data, except one small section of people at the age of 50, show any significantly greater relative risk factor (more than 2.0) even in people with a BMI over 40.

 

BMI range <18.5 18.5–20.9 21.0–23.4 23.5–24.9 25.0–26.4 26.5–27.9 28.0–29.9 30.0–34.9 35.0–39.9 ≥40.0

No. of deaths               333 1513 5229 5768 6657 6021 6355 7488 2028 781

Age-standardized rate† 3520 2430 1520 1320 1270 1310 1440 1680 2260 3210

Multivariate relative risk 1.97 1.54 1.14 1.00‡ 0.95 0.95 1.00 1.10 1.35 1.83

 

The Relative Risk Factor (RR) is only .8 lower in the so called normal range than in the severely obese range.  Also the RR in the "overweight" range was actually slightly lower than that in the normal range and that the RR in the underweight range is slightly higher than that of people with a BMI over 40.  These findings are similar to those of the Cooper Institute studies and those of the CDC.
 
In the tiny subsection of data, of those over 50 years of age which did show a higher RR in people with a BMI over 40, the differential was 2.2 which is high enough to be significant but not super high.
 
An excerpt of the data follows:

<18.5 18.5–20.9 21.0–23.4 23.5–24.9 25.0–26.4 26.5–27.9 28.0–29.9 30.0–34.9 35.0–39.9 ≥40.0

No. of deaths                  133 796 3567 3812 4113 3262 2728 2910 627 212

Age-adjusted relative risk 1.81 1.36 1.06 1.00† 1.01 1.13 1.27 1.66 2.26 3.22

As often does the news media in these stories, the study was reported as finding that  all fat people die sooner than slim people, ignoring that most of the data did not show that at all.

Scientists generally do not like to reveal to the public the uncertainties that are associated with their research. It might make them look less expert. Sometimes it's just too complicated to explain all the uncertainties. Whatever the reason, claims that scientists make are usually more dramatic and confident than can be defended with the science alone." (Dr Roy Spencer, former senior scientist climatologist with NASA in his book, CLIMATE CONFUSION, NY, 2008)

One other thing should be kept in mind about this study. This was self reported data. And self reported data is notoriously inaccurate.

On "The Today Show", their medical advisor stated that women tend to lie to their doctors about several things - among which are how much they exercise (most people overstate their amount of exercise), whether they smoke (many women understate their smoking habits) and how much they eat in a day (few actually count calories and if you don't, it's easy to fool yourself about the amount of food you are consuming).  It can be assumed that when they fill out surveys for studies, they might be LESS honest than they are with their doctors and not MORE honest! :)

It is important to read these studies because if we want to be healthy, dieting or calorie cutting or "losing weight" may not be the way to best achieve health.  Getting on a healthy lifestyle of exercise and good food choices will make us healthier at ANY weight and that is what clinical studies have suggested.  For example, see the HAES study, USC.   One of the researchers on this study, Dr Linda Bacon, wrote a book which is very informative.

source: http://content.nejm.org/cgi/content/short/355/8/763