New research has disproved the idea that there is an “obesity paradox”“, according to which heart failure patients who are overweight or obese are thought to be less likely to end up in hospital or die than people of normal weight.
The study, published in el ‘European Heart Journal’, shows that if doctors measure the waist-to-height ratio of their patients, instead of looking at their body mass index (BMI), the supposed survival advantage of people with a BMI of 25 kg/m2 or more.
false theories
The “obesity paradox” refers to counterintuitive findings that suggest that although people who are overweight or obese are at increased risk of developing heart problems, once a person has developed a heart condition, those with a lower BMI tall seemed to do better and were less likely to die than those of normal weight.
Various explanations have been suggested, including the fact that once someone has developed pcardiac problemsa little extra fat somewhat protects against later health problems and death, especially since people who develop serious and chronic disease often lose weight.
“Obesity can’t be good”
John McMurray, Professor of Medical Cardiology at the University of Glasgow (United Kingdom), who led the latest research, explains that “it has been suggested that living with obesity is good for patients with heart failure and reduced ejection fraction, which is when the heart’s main chamber is unable to squeeze out normal amounts of blood. We knew that this could not be true and that obesity must be bad instead of good,” he acknowledges. We thought part of the problem was that BMI was a weak indicator of the amount of fat tissue in a patient.”
how they write Professor Stephan von Haehling, Consultant Cardiologist, and Dr Ryosuke Sato, associate researcher, both from Göttingen University Medical Center, Germany, in an accompanying editorial, BMI does not take into account body composition of fat, muscle, and bone, or where the fat is distributed.
The sumo wrestler and the American wrestler
“Would it be feasible to assume that an American professional wrestler (more muscle) and a Japanese sumo wrestler (more fat) with the same BMI would have a similar risk of cardiovascular disease?” Arnold Schwarzenegger in his younger years, when starred in ‘Terminator’, with a BMI of about 30 kg/m2″.
This study is the first to examine different ways of measuring patient size and proportions, including BMI, but also anthropometric measures such as waist-to-height ratio, waist circumference, and waist circumference. waist to hip ratio, and adjusts patient outcomes to account for other factors that play a role in or predict these outcomes, such as levels of natriuretic peptides, hormones that are released into the blood when the heart is under pressure, as occurs with heart failure.
“Natriuretic peptides are the variablee more important prognosis in patients with heart failure. Normally, natriuretic peptide levels are increased in people with heart failure, but obese patients have lower levels than normal-weight patients,” explains McMurray.
I study almost 10,000 people
McMurray and colleagues analyzed data from 1,832 women and 6,567 men with heart failure and reduced ejection fraction who participated in the international randomized controlled trial PARADIGM-HF, conducted at 47 countries from six continents. When the patients were randomized, the physicians collected data on BMI, blood pressure, anthropometric measurements, blood test results, medical history, and treatments. The researchers were interested in knowing which patients were hospitalized for heart failure or died from it.
An “obesity-survival paradox” was observed, in which mortality rates were lower in people with a BMI of 25 kg/m2 or greater, but this paradox disappeared when the researchers adjusted the results to account for all factors that may affect results, including natriuretic peptide levels.
The paradox is dismantled
First author of the study, Dr Jawad Butt, a researcher at Copenhagen-Rigshospitalet University Hospital, Copenhagen, Denmark, who carried out the analyses, notes that “the paradox was much less apparent when looking at waist-to-height ratio, and disappeared after adjusting for prognostic variables.
“After adjustment, both BMI and waist-to-height ratio showed that more body fat was associated with increased risk of death or hospitalization for heart failure, but this was more evident for waist-to-height ratio,” he continued. — When the waist-height ratio was analyzed, it was observed that the fattest 20% had a 39% higher risk of being hospitalized for heart failure“.
According to McMurray, the study “demonstrates that there is no ‘obesity survival paradox’ when we use better measures of body fat. BMI does not take into account the location of fat on the body or its amount relative to muscle or skeletal weight, which they may differ by gender, age, and race. In heart failure specifically, retained fluid also contributes to body weight.”