Studies published over the last couple of years had oddly suggested that people who have been diagnosed with cardiovascular disease can expect to live longer if they are overweight or obese. This contradictory association has been called the “obesity paradox.”
It’s well established that being overweight or obese — defined as having a body-mass index (BMI) over 25 — is linked to health risks like cardiovascular disease, osteoarthritis, diabetes, and cancer, to name a few. But what of this so-called obesity paradox? How can we explain it? Well, a new study published in the journal Jama Cardiology suggests there’s not much to debate — we’ve misinterpreted the data all along.
That’s according to researchers at Northwestern University. Dr. Sadiya Khan, an assistant professor of medicine at Northwestern University Feinberg School of Medicine, along with colleagues, examined individual-level data pertaining to over 190,000 in-person examinations. At the time of enrollment, all participants were free of cardiovascular disease. This proved to be critical to debunking the “obesity paradox.”
There isn’t any paradox at all. People of unhealthy weight live unhealthily.
“Recent data have suggested that individuals with cardiovascular disease who are obese may live longer. But, we were able to investigate this in the greater context of healthspan and cardiovascular morbidity and shed light on this controversy by using a lifespan perspective beginning prior to the onset of cardiovascular disease. We are able to provide clear perspective of increased cardiovascular burden in overweight and obese,” Khan told ZME Science.
The data was sourced from 10 large prospective cohorts with an aggregate of 3.2 million years of follow-up. Over follow-up, researchers assessed whether or not participants had acquired any cardiovascular disease, including coronary heart disease, stroke, and heart failure. The researchers also recorded whether fatalities were due to cardiovascular or non-cardiovascular reasons.
This thorough examination shows that there’s a similar longevity between people who are of normal weight and overweight. However, overweight and obese individuals had a much higher risk of developing cardiovascular disease and spent more years with cardiovascular disease than those of normal weight.
Overall, overweight and obese individuals had higher odds of developing a stroke, having a heart attack or heart failure, or dying from heart disease than people of normal weight. Key findings from the study include:
The likelihood of having a stroke, heart attack, heart failure or cardiovascular death in overweight middle-aged men 40 to 59 years old was 21 percent higher than in normal weight men. The odds were 32 percent higher in overweight women than normal weight women.
The likelihood of having a stroke, heart attack, heart failure or cardiovascular death in obese middle-aged men 40 to 59 years old was 67 percent higher than in normal weight men. The odds were 85 percent higher in obese women than normal weight women.
Normal weight middle-aged men also lived 1.9 years longer than obese men and six years longer than morbidly obese. Normal weight men had similar longevity to overweight men.
Normal weight middle-aged women lived 1.4 years longer than overweight women, 3.4 years longer than obese women and six years longer than morbidly obese women.
This is the first study to provide a lifespan perspective on the risks of developing cardiovascular disease for normal weight, overweight, and obese individuals. Its findings are greatly welcomed seeing how the obesity paradox has seeded confusion and may even have caused harm. Suddenly, people would wonder why they should go through the effort of losing weight when research showed they are going to live longer. We now know this isn’t the case. What’s more, losing weight doesn’t only reduce the incidence of cardiovascular disease, but also other afflictions like diabetes or cancer.
“Future research needs to focus on strategies for primordial prevention to reduce the burden of cardiovascular disease in the population as a whole. We are also interested in identifying the differences in healthcare costs related to cardiovascular morbidity and mortality associated with overweight and obese,” Khan said.
At the end of the day, people should always strive to hover at a normal weight. Even if the obesity paradox were true — and it isn’t — what good is it living a bit longer in an unhealthy body?
“Maintaining a healthy or normal BMI throughout younger to older adulthood is associated with a longer, healthier life!” Khan told our readers.
Scientific reference: Sadiya S. Khan, Hongyan Ning, John T. Wilkins, Norrina Allen, Mercedes Carnethon, Jarett D. Berry, Ranya N. Sweis, Donald M. Lloyd-Jones. Association of Body Mass Index With Lifetime Risk of Cardiovascular Disease and Compression of Morbidity. JAMA Cardiology, 2018; DOI: 10.1001/jamacardio.2018.0022.
Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines.