Study shows ‘obesity paradox’ does not exist

Heart failure — also known as congestive heart failure — occurs when the heart becomes too damaged to pump enough blood throughout the body.

Symptoms of heart failure include:

Any disease that damages the heart muscle can cause heart failure, including:

There are a number of modifiable risk factors that can help lower a person’s chances of developing heart failure. These include taking steps to avoid or control:

The body mass index (BMI) was unveiled in the 19th century but was not highly used until the 1970s.

BMI uses a calculation that divides a person’s weight by their height squared. The result of this calculation is designed to tell if an adult may be underweight, overweight, or at normal weight.

• a BMI below 18.5: underweight
• a BMI of 18.5 to 24.9: normal weight
• a BMI of 25 to 29.9: overweight
• a BMI of 30 or more: obese

Over the past few years, doctors have started to question the accuracy of BMI as it does not distinguish between muscle and fat.

For this reason, some researchers are now moving toward the waist-to-height ratio as a substitution for BMI.

This measurement takes a person’s waist circumference divided by their height.

Additionally, the measurement of your waist circumference is also used as an indicator of a higher risk of type 2 diabetes, coronary artery, disease, and high blood pressure. These include:

• A man with a waist circumference of more than 40 inches
• A non-pregnant woman with a waist circumference of more than 35 inches

For this study, researchers analyzed data from more than 1,800 women and more than 6,500 men with heart failure and reduced ejection fraction who were enrolled in the PARADIGM-HF international randomized controlled trial taking place in 47 countries on six continents.

This data included information on BMI, body measurements, and other test results.

Upon analysis, scientists reported that both the data on BMI and waist-to-height ratio showed an increased amount of body fat was associated with a greater risk of hospitalization for heart failure or death.

The research team found this was even more evident when examining study participants’ waist-to-height ratio. When focusing only on that ratio, scientists found the top 20% of participants with the most body fat had a 39% greater chance of being hospitalized for heart failure, compared to participants in the bottom 20% who had the least amount of body fat.

“Our study shows there is no ‘obesity survival paradox’ when we use better ways of measuring body fat,” said Dr. John McMurray, professor of medical cardiology at the University of Glasgow and lead researcher of this study. “BMI does not take into account the location of fat in the body or its amount relative to muscle or the weight of the skeleton, which may differ according to sex, age, and race.”

“In heart failure specifically, retained fluid also contributes to body weight,” he added. “Our study has clarified the true relationship between body fat and heart failure patient outcomes, showing that greater obesity is actually associated with worse not better outcomes, including high rates of hospitalization and worse health-related quality of life.”

After reviewing this research, Dr. Jonathan Fialkow, a cardiologist at Miami Cardiac & Vascular Institute, part of Baptist Health South Florida who was not involved in the study, told Medical News Today he was not surprised by the results.

“It’s fairly common in medicine to have early observation studies draw correlations — like higher BMI means lower heart failure hospitalization and death — that are then contradicted with a deeper look into the conditions and results,” he explained. “Obesity drives cardiac conditions including heart failure, and outcomes are worse with obesity. There is no paradox.”

Fialkow said weight control completed through more than just looking at BMI remains of paramount importance in heart failure prevention and control.

“Some of the pre-existing, poorly researched messaging can give an obese heart failure patient conflicting goals such that they do not recognize the need for weight loss by saying that it’s better for them to be overweight,” he said. “Hopefully, this and future studies will validate the scientific/medical knowledge regarding avoiding obesity in heart failure.”

Medical News Today also spoke with Dr. Nicole Weinberg, a cardiologist at Providence Saint John’s Health Center in California, not involved in this study, about this research.

She said researchers are constantly coming up with new assessment tools for doctors to utilize.

“Not necessarily just trusting BMI, which is one of the things that they were saying that they’re not using very much for this patient population, but trying to really flesh out how we use these measurements, how we put our patients into different categories, and then what we do with them once they’re in the set category,” Weinberg said.