Study: The Heavier You Are, the More Likely You Are to Die Early

A massive meta-analysis found a correlation between BMI and mortality risk.

Obesity paradox

Photo via Chiang

A huge study led by researchers from the Harvard T.H. Chan School of Public Health offers a wake-up call for the millions of Americans who are overweight or obese. The heavier you are, the study says, the more likely you are to die early.

The result is a major challenge to the “obesity paradox,” the idea that overweight people may actually live longer than their thin peers. In fact, the cohort—hundreds of investigators, led by researchers from Harvard and the University of Cambridge—behind the new study found just the opposite.

By pooling results from 239 prior studies, which tracked participants for an average of 14 years, the researchers saw a clear relationship between a high body mass index (BMI) and premature death. As BMIs increased, they saw, so too did study subjects’ mortality risks.

People who had BMIs between 22.5 and 25—healthy, but not too thin—had the lowest observed mortality risk. After that, every five-point jump in BMI (from 25 to 30, for example) was associated with a 31 percent higher chance of premature death. Severely obese individuals, with BMIs between 40 and 60, had a whopping three-fold higher mortality risk than those at the bottom of the range.

Prior studies supporting the obesity paradox, the researchers say, have not accounted for ways in which a low body weight may suggest underlying health problems that could lead to premature death, such as long-term illness or a smoking habit. To remove those biases in the new research, they opted not to analyze current or former smokers, people with chronic diseases, or subjects who died during the first five years of study follow-up. That left about 4 million people.

In addition to the correlation between BMI and overall mortality risk, the researchers found that each five-point jump in BMI corresponded to a 49 percent increase in cardiovascular mortality, a 38 percent increase in respiratory mortality, and a 19 percent increase in cancer mortality. Young men seemed to feel those effects most acutely.

No matter which way you slice it, the study provides pretty compelling reasons to keep weight down and activity levels up.