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Member Research & Reports

Member Research & Reports

Northwestern: New Findings Contradict ‘Obesity Paradox’

A new Northwestern Medicine study published in JAMA Cardiology debunks the “obesity paradox,” a counterintuitive finding that showed people who have been diagnosed with cardiovascular disease live longer if they are overweight or obese compared with people who are normal weight at the time of diagnosis.

Obese people live shorter lives and have a greater proportion of life with cardiovascular disease, according to the study’s findings.

The new study shows similar longevity between normal weight and overweight people, but a higher risk for those who are overweight of developing cardiovascular disease during their lifespan and more years spent with cardiovascular disease.

This is the first study to provide a lifespan perspective on the risks of developing cardiovascular disease and dying after a diagnosis of cardiovascular disease for normal weight, overweight, and obese individuals.

“The obesity paradox caused a lot of confusion and potential damage because we know there are cardiovascular and non-cardiovascular risks associated with obesity,” said Dr. Sadiya Khan, assistant professor of medicine in the division of cardiology and a Northwestern Medicine cardiologist.

“I get a lot of patients who ask, ‘Why do I need to lose weight, if research says I’m going to live longer?’” said Dr. Khan, also an assistant professor of preventive medicine. “I tell them losing weight doesn’t just reduce the risk of developing heart disease, but other diseases like cancer. Our data show you will live longer and healthier at a normal weight.”

Obesity is defined as having a Body Mass Index (BMI) of 30 to 39.9; overweight is 25 to 29.9. BMI is a person’s weight divided by his or her height. An individual who is 5 feet and 4 inches and weighs 160 pounds, for example, would be considered overweight; a person who is 5 feet and 4 inches and weighs 190 pounds is considered obese.

According to the study:

“A healthy weight promotes healthy longevity or longer healthspan in addition to lifespan, so that greater years lived are also healthier years lived,” Dr. Khan said. “It’s about having a much better quality of life.”

The study examined individual level data from 190,672 in-person examinations across 10 large prospective cohorts with an aggregate of 3.2 million years of follow-up. All of the participants were free of cardiovascular disease at baseline and had objectively measured height and weight to assess BMI. Over follow-up, investigators assessed for cardiovascular disease overall and by type, including coronary heart disease, stroke, heart failure and cardiovascular death, as well as non-cardiovascular death.

Other Northwestern authors include senior author Dr. Donald Lloyd-Jones, senior associate dean for clinical and translational research and chair of preventive medicine, along with co-authors Dr. Mercedes Carnethon, vice chair and chief of epidemiology in the department of preventive medicine; Dr. John Wilkins, assistant professor of medicine in the division of cardiology and of preventive medicine; Dr. Norrina Allen, associate professor of preventive medicine in the division of epidemiology; Dr. Ranya Sweis, assistant professor of medicine in the division of cardiology; and Dr. Hongyan Ning biostatistician in the department of preventive medicine.

The study was supported by grants R21 HL085375 F32 HL129695 from the National Institutes of Health/National Heart, Lung, and Blood Institute.

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