Overweight-the killer in plain sight

The BMI measure has given us the obesity paradox—being overweight or even slightly obese protects us against an early death. But iron out the anomalies, and the true impact of extra weight is revealed

- Bryan Hubbard

Have that last piece of pizza. You know you want to, and anyway, medical science tells us it might even be good for you. People who are a little overweight pleasantly plump, perhaps have the greatest protection against a range of chronic health problems and could even live longer, we’ve been told.

It’s known as the obesity paradox. According to BMI (body-mass index) measures, obesity is defined as any score over 30. But those who are merely overweight with a BMI of 25 to 29.9 are at the lowest risk of an early death, so it seems as if that little bit of fat around the middle helps you live longer. In a U-shape of risk, the overweight enjoy the same protection as the slim, who have a BMI score of 18.5 to 24.9.

Even stranger, people classified as underweight with a BMI of 18.5 or lower are at the highest risk, like the morbidly obese with a score of 35 or higher, of an early death. And young people with a low BMI of 18.5 to 24.9 are more likely to suffer arterial stiffness, a precursor of cardiovascular disease.

“Obesity alone may confer a survival benefit independent of age, medical care or therapy . . . perhaps the definition of obesity needs to be revisited,” said researchers at the Naval Medical Center in San Diego. It’s hard to argue with the science that uses the BMI score, the go-to measure for predicting health and longevity. While doctors used to rely on simple weight and height calculations to judge body fat, they now use the more precise BMI score, which is arrived at by dividing weight in kilograms by height in meters squared.