Higher levels of obesity associated with increased risk of death

At least part of the good results for being slightly overweight might be due to the fact that they are more likely to survive surgery and some illnesses, perhaps because of energy reserves.

http://www.eurekalert.org/pub_releases/2013-01/jaaj-hlo122712.php

Public release date: 1-Jan-2013
Contact: Karen Hunter
JAMA and Archives Journals
Higher levels of obesity associated with increased risk of death
Being overweight associated with lower risk of death

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.

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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.

The researchers add that their findings are consistent with observations of lower mortality among overweight and moderately obese patients. "Possible explanations have included earlier presentation of heavier patients, greater likelihood of receiving optimal medical treatment, cardioprotective metabolic effects of increased body fat, and benefits of higher metabolic reserves."