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High BMI might mean a longer life. Eat up?

Map via CDC Behavioral Risk Factor Surveillance System (BRFSS)

First, we’re told it’s unhealthy to have high body mass index (BMI). Now, researchers at the CDC’s National Center for Health Statistics find that being overweight may actually be associated with a lower all-cause mortality.

I’m stumped. Which is it?

BMI is a formula that calculates a person’s weight to their height, and categorizes him or her as underweight, normal, overweight or obese.

But is the measure a good indicator for measuring a person’s health? Can it really be true that having a higher BMI means longevity or better health?

I asked Ellen W. Demerath, Ph.D., an expert from the Division of Epidemiology & Community Health at the University of Minnesota School of Public Health, to shed some light on the findings.

“At first glance, it may seem that the recent findings are telling us that being overweight is beneficial,” said Demerath. “However, there are a number of reasons why this is not the right interpretation.”

Demerath explained that beneath the statistics themselves, there may be some underlying factors that help explain why overweight individuals avoid some causes of death that impact others.

  • People who are overweight are more likely to be followed up for risk factors than normal weight individuals.
  • Older individuals are at the greatest risk of death, and those with extra weight may have additional muscle mass and strength to avoid falls.
  • It is possible that in conditions such as cancer – which involve loss of body mass – additional weight may delay death.

BMI is a gauge of obesity, but it doesn’t take into account the individual’s overall health.

“Overweight individuals (BMI 25-29) are known to have an increased risk of illness compared to individuals in the normal weight range (BMI 18.5 – 24.9),” said Demerath. “For instance, the prevalence of high blood pressure increases progressively with higher levels of BMI in men and women.”

While this means individuals may be more likely to see physicians and be followed up for risk factors, it also means overall poor health may take a toll on their bodies.

The verdict seems to be in.  Though in some cases higher BMI may lead to a longer life, it is not an actual indicator of longevity, nor does it mean the person’s life will in fact be a healthy one.

“It is well known that excess weight can reduce wellbeing through its association with osteoarthritis and joint pain, sleep disturbances, and other conditions,” Demerath said. “That being said, the focus should be on optimizing not only the quantity of time we live but also the quality of our lives and our wellbeing.”

Interested in knowing your BMI? Click here for the CDC’s adult BMI calculator.

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