Research spells out the number of years obesity shaves off a life

New research shows people who suffer from overweight and obesity are at greater risk of dying sooner than people who don't. The finding pokes holes in the so-called "obesity paradox."

There are approximately 2.1 billion people in the world who are overweight or obese, categories determined by calculating body mass index (BMI), which is a person's weight in kilograms divided by the square of their height in meters. For example, someone who is 5 ft 9 and 169 lbs would have a BMI of 25, the threshold for being overweight. (Though not everyone agrees that BMI is the best tool for measuring weight issues.)

In America, in particular, the public health problem related to weight is staggering, with two-thirds of the population considered overweight or obese. It’s a growing health crisis that’s spurred, in part, by physical inactivity, adverse medical conditions, and poor nutrition, exacerbated by the abundance and availability of ultra-processed foods and, in some cases, a lack of access to healthy foods, according to the National Institutes of Health. If left unaddressed, being overweight or obese can lead to type 2 diabetes, heart disease, and an increased risk of some cancers.

New research published today (Feb. 28) in the Journal of the American Medical Association (JAMA) lays out the deadly role weight can play on a person, and just how many years it can shave off their overall lifespan.

Researchers from Northwestern and Southwestern universities joined forces to undertake a large, population-modeled analysis in which they tracked more than 190,000 Americans from 1964 to 2015, taking specific care to focus on the 15% of them who developed heart-related conditions during their lifetimes.

They found that, on average, men within a healthy weight range lived about six years longer than men who were morbidly obese. Women suffering from morbid obesity tended to live two fewer years than women who were considered in a healthy weight range.

The study’s findings run counter to the obesity paradox, which is a medical hypothesis that people who are overweight and obese are linked with higher survival rates. It’s an idea first came suggested in a 2003 studypublished in the Journal of the International Society of Nephrology. It has since been supported by a handful of other studies, including one in 2013 that was published in JAMA (the same journal publishing the study this week contradicting the concept). The 2013 research analysis has been criticized for its omission of several large, cohort studies that would have affected its findings.

The new research used data collected as part of the Cardiovascular Disease Lifetime Risk Pooling Project, which accounts for at least five decades of population-based cohort studies in the US. In this case, they pulled out 10 cohort studies that allowed them to track people who developed heart disease during the course of their lifetimes, taking into account information participants shared during examinations, as well as at least 10 years of follow-up information. Unlike in previous research, this analysis tracked people by age across an entire lifetime and by the severity of their overweight and obesity.

The new research is especially concerning given that the rate of younger people and children developing obesity and its related conditions (heart disease especially) is expected to grow. Another study published this week (Feb. 26) in the journal Pediatrics showed childhood obesity maintained its upward trend in 2016, with 35% of US children considered overweight, a 4.7% increase from 2014.

“The economic implications of direct and indirect medical costs of the overweight and obesity epidemic are enormous, and total health care costs attributable to overweight and obesity are estimated to exceed $800 billion by 2030 if current trends persist,” the study states.

 The Centers for Disease Control and Prevention estimated the medical cost of obesity in the US at $147 billion in 2008—and that didn't include the more than $3 billion estimated to have been lost to people missing work due to weight-related health problems.