Avian Flu Diary: Studies Weigh In On The `Obesity Paradox’

Photo Credit CDC PHIL

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While just about everyone will concede that being lean and athletic is preferable to being soft and pudgy, there is a growing body of evidence that – with some medical conditions, at least - having a bit of extra poundage could be beneficial to your long-term survival.

Research has shown that patients having a BMI > 30 actually are more likely to survive certain medical conditions than patients with a normal or below-normal body mass index.

It’s called the `Obesity Paradox’, and quite frankly, it’s been driving doctors and researchers just a little bit nuts for years.

Now, before anyone cries `foul’, there are plenty of health risks that come from being obese, including diabetes, coronary artery disease, sleep apena, hypertension, and stroke. The point here isn’t that being overweight is healthier.

it isn’t.

But for people with certain medical conditions, including diabetes, congestive heart failure, kidney dialysis, heart attacks, and Asthma - carrying extra pounds appears to improve their outcomes.

This curious (and controversial) finding was first described in the literature in 1999, regarding survival rates of patients on kidney dialysis (see Influence of excess weight on mortality and hospital stay in 1346 hemodialysis patients).

Since then, this phenomenon has inspired a good deal of research, much of it coming to similar conclusions.

Overnight we saw this press release come from the American College of Chest Physicians.

'Obesity paradox': Extra weight linked to better outcomes for septic shock, asthma exacerbation

Although obesity is linked to a variety of health risks, new research indicates that obese patients may have an advantage over nonobese patients in certain health situations, including septic shock and acute asthma exacerbation.

In two separate studies presented at CHEST 2012, the annual meeting of the American College of Chest Physicians, researchers compared outcomes in obese (BMI >30) vs nonobese patients with either septic shock or acute asthma exacerbation. Results showed that, although obese patients with asthma are more at risk for asthma exacerbations, near fatal exacerbations were more prevalent in nonobese patients.

Likewise, obese patients with septic shock had decreased mortality compared with nonobese patients. Researchers attribute this "obesity paradox" partly to a blunted pro-inflammatory cytokine response in obese patients.

Recently, JAMA published a pooled analysis of 5 cohort studies that found – surprisingly – that : “Adults who were normal weight at the time of incident diabetes had higher mortality than adults who are overweight or obese.”

Original Contribution | August 8, 2012

Association of Weight Status With Mortality in Adults With Incident Diabetes

Mercedes R. Carnethon, PhD; Peter John D. De Chavez, MS; Mary L. Biggs, PhD; Cora E. Lewis, MD; James S. Pankow, PhD; Alain G. Bertoni, MD, MS; Sherita H. Golden, MD, MS; Kiang Liu, PhD; Kenneth J. Mukamal, MD, MPH; Brenda Campbell-Jenkins, PhD; Alan R. Dyer, PhD

JAMA. 2012;308(6):581-590. doi:10.1001/jama.2012.9282.

We’ve another large study out of Sweden that looked at patient outcomes with acute coronary syndromes (ACSs) – and you guessed it – obese patients had better survival rates after a heart attack than patients of normal weight.

Evidence for obesity paradox in patients with acute coronary syndromes: a report from the Swedish Coronary Angiography and Angioplasty Registry

Oskar Angerås, Per Albertsson, Kristjan Karason, Truls Råmunddal, Göran Matejka, Stefan James, Bo Lagerqvist, Annika Rosengren and Elmir Omerovic

Conclusion In this large and unselected group of patients with ACSs, the relation between BMI and mortality was U-shaped, with the nadir among overweight or obese patients and underweight and normal-weight patients having the highest risk. These data strengthen the concept of the obesity paradox substantially.

Similarly, from the American Journal of Cardiology, we get this study from earlier this summer, on survival rates of patients with congestive heart failure.

Volume 110, Issue 1 , Pages 77-82, 1 July 2012

The Obesity Paradox in Men Versus Women With Systolic Heart Failure

Adrienne L. Clark, BA, Jennifer Chyu, Tamara B. Horwich, MD, MS

Abstract (excerpt):

In multivariate analyses, normal BMI and normal WC were associated with higher relative risk for the primary outcome in men (BMI 1.34, WC 2.02) and women (BMI 1.38, WC 2.99). In conclusion, in patients with advanced HF, high BMI and WC were associated with improved outcomes in both genders. Further investigation of the interaction between body composition and gender in HF outcomes is warranted.

Admittedly, many of these medical conditions may well have been brought on by the patient’s obesity to start with, so none of these results should be construed as a green light for binge eating brownies.

As to why obese individuals may fare better with certain medical conditions that those of normal, or below normal, weight?

There are plenty of theories.

It has been suggested that heavier patients may develop medical conditions earlier, may get more aggressive treatment, and thereby have a survival advantage.
Some theorize that hospitalizations and chronic illnesses – which often induce weight loss - put those without fat reserves at a disadvantage.
There is even speculation that adipose tissue may secrete protective cytokines and hormones (cite).

The truth is, no one really knows.

Finally, in 2005 epidemiologist Katherine Flegal published a study called Excess deaths associated with underweight, overweight, and obesity that looked at data from two decades of NHANES surveys, and found that mortality among those slightly overweight (BMI 25 -29) was less than those in the `normal’ weight category (BMI 20 -25).