Study: Being underweight worse than being obese

Researchers say relationship between BMI, mortality unclear

Published On: Jul 12 2012 12:00:59 PM EDT   Updated On: Jul 13 2012 11:49:22 AM EDT

A new study suggests that it may be far more dangerous to have your doctor assess you as "underweight" than it is to be diagnosed as "obese."

Researchers at the University of California Davis School of Medicine said they surveyed 50,994 Americans aged 18 to 90 years old, over a period of six years, in an effort to examine the association between body mass index and mortality in a representative, contemporary U.S. sample.

They published their findings in the Journal of the American Board of Family Medicine.

What they found was that based on the BMI system, being underweight was significantly associated with increased mortality risk, whereas being overweight was significantly associated with reduced mortality risk.

Severe obesity was associated with increased mortality risk, but only after the association was accounted for by coexisting diabetes and hypertension.

According to the study's authors, Anthony Jerant, MD, and Peter Franks, MD, "Overweight and obesity have increased dramatically, with adverse public health implications. Above-normal BMI is associated with decreased functional ability and health status and increased risk of chronic conditions such as diabetes and hypertension, which often cause further decrements in health. However, the contemporary relationship between BMI and mortality, and how BMI interacts with diabetes and hypertension to influence mortality, are unclear."

The researchers concluded that their findings raise the question of whether efforts to reduce mortality should be targeted primarily to commonly co-occurring health risks associated with increased mortality risk, such as physical inactivity and smoking, rather than weight.

According to the National Institute of Health, BMI, which was developed in Europe in the late 19th century, is a measure of body fat based on height and weight that applies to adult men and women. Based on the BMI system, an adult with a BMI below 18.5 is considered underweight, an adult who has a BMI between 25 and 29.9 is considered overweight and an adult who has a BMI of 30 or higher is considered obese.

To read the original study, click here.