Photo Credit CDC PHIL
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*** UPDATED ***
This study, which I knew would be controversial, has sparked serious rebukes from some members of the medical community. In the Interest of fairness, here is a link to an article from BBC News, where a number of doctors take issue with its findings.
'Weight is healthy' study criticised
A study which suggests being overweight can lead to a longer life has caused controversy among obesity experts.
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As someone who has been `gravitationally challenged’ nearly all of his life, I naturally have concerns that my extra poundage may be cutting into my lifespan.
While aesthetically, thinner may be perceived by many as being better, increasingly we are seeing evidence to suggest that carrying a few extra pounds may actually extend one’s lifespan, not shorten it.
Last October, in Studies Weigh In On The `Obesity Paradox’, we looked at research that suggested that for people with certain medical conditions, including diabetes, congestive heart failure, kidney dialysis, heart attacks, and Asthma - carrying some extra weight appears to improve their outcomes
Now, in a study published in JAMA, we have the most comprehensive look to date at all-cause mortality spanning nearly 3 million people (and 270,000 deaths), and sorted by BMI (Body Mass Index) classification.
Photo Credit JAMA Report Video
The results, consistent across all ages and ethnic groups, indicated that while BMI’s over 35 (Class 2 and Class 3 obesity) increase overall mortality, that simply being overweight (BMI 25-<30) was associated with a significant reduction in all-cause mortality.
And even those who fell into the next higher BMI category (class 1 obesity) saw a 5% reduction in overall mortality compared to those falling into the normal weight BMI (18.5-<25).
Mortality rates do jump considerably once you reach a BMI > 35 ( resulting in a 29% increased risk of death for obesity grades 2 and 3). The HHS maintains an online BMI calculator HERE, where you can input your height and weight and quickly find out your number.
The JAMA article, which is heavy in statistics and details, is freely available at the following link.
Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index Categories: A Systematic Review and Meta-analysis
Katherine M. Flegal, PhD; Brian K. Kit, MD; Heather Orpana, PhD; Barry I. Graubard, PhD
Conclusions and Relevance Relative to normal weight, both obesity (all grades) and grades 2 and 3 obesity were associated with significantly higher all-cause mortality. Grade 1 obesity overall was not associated with higher mortality, and overweight was associated with significantly lower all-cause mortality. The use of predefined standard BMI groupings can facilitate between-study comparisons.
Several brief videos, and press release (excerpts below) can be viewed at:
Higher Levels of Obesity Associated With Increased Risk of Death; Being Overweight Associated With Lower Risk of Death
EMBARGOED FOR RELEASE: 3 P.M. (CT) TUESDAY, JANUARY 1, 2013
CHICAGO – In an analysis of nearly 100 studies that included approximately 3 million adults, relative to normal weight, overall obesity (combining all grades) and higher levels of obesity were both associated with a significantly higher all-cause risk of death, while overweight was associated with significantly lower all-cause mortality, according to a study in the January 2 issue of JAMA.
“Estimates of the relative mortality risks associated with normal weight, overweight, and obesity may help to inform decision making in the clinical setting,” according to background information in the article.
Katherine M. Flegal, Ph.D., of the National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Md., and colleagues conducted a study to compile and summarize published analyses of body mass index (BMI) and all-cause mortality that provide hazard ratios (HRs) for standard BMI categories. For the review and meta-analysis, the researchers identified 97 studies that met inclusion criteria, which provided a combined sample size of more than 2.88 million individuals and more than 270,000 deaths. Regions of origin of participants included the United States or Canada (n = 41 studies), Europe (n = 37), Australia (n = 7), China or Taiwan (n = 4), Japan (n = 2), Brazil (n = 2), Israel (n = 2), India (n = l), and Mexico (n = l).
All-cause mortality HRs for overweight (BMI of 25-<30), obesity (BMI of ≥30), grade 1 obesity (BMI of 30-<35), and grades 2 and 3 obesity (BMI of ≥35) were calculated relative to normal weight (BMI of 18.5-<25).
The researchers found that the summary HRs indicated a 6 percent lower risk of death for overweight; a 18 percent higher risk of death for obesity (all grades); a 5 percent lower risk of death for grade 1 obesity; and a 29 percent increased risk of death for grades 2 and 3 obesity.
The authors note that the finding that grade 1 obesity was not associated with higher mortality suggests that that the excess mortality in obesity may predominantly be due to elevated mortality at higher BMI levels.
In an accompanying editorial, Does Body Mass Index Adequately Convey a Patient’s Mortality Risk?, authors Steven B. Heymsfield, MD and William T. Cefalu, MD write:
The presence of a wasting disease, heart disease, diabetes, renal dialysis, or older age are all associated with an inverse relationship between BMI and mortality rate, an observation termed the obesity paradox or reverse epidemiology. The optimal BMI linked with lowest mortality in patients with chronic disease may be within the overweight and obesity range. Even in the absence of chronic disease, small excess amounts of adipose tissue may provide needed energy reserves during acute catabolic illnesses, have beneficial mechanical effects with some types of traumatic injuries, and convey other salutary effects that need to be investigated in light of the studies by Flegal et al and others.”
“Not all patients classified as being overweight or having grade 1 obesity, particularly those with chronic diseases, can be assumed to require weight loss treatment. Establishing BMI is only the first step toward a more comprehensive risk evaluation.”
While I can think of many other disadvantages to being overweight (my dreaded fear of wicker furniture being one), it appears that at least in terms of overall mortality - carrying a few extra pounds may actually turn out to be desirable - particularly among those who have chronic ailments.
