A new study has found that belly fat is a stronger predictor of heart disease risk than body mass index alone, challenging a measure that doctors have relied on for decades.
The results were published August 11 in the Journal of the American College of Cardiology. Researchers analyzed health data from nearly 260,000 people who had either waist circumference or waist-to-hip ratio measurements on record.
According to the report in Healthline, researchers found that people who were at a healthy weight or who had overweight, but who had a clinically high waist circumference or waist-to-hip ratio, had a 15% to 50% higher risk for serious heart disease outcomes. Those outcomes included fatal or non-fatal heart attack, stroke, heart failure, atrial fibrillation, and death from cardiovascular disease.
The study's senior author, Michael J. Blaha, MD, MPH, director of the Cardiometabolic Clinic at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, explained the key distinction between types of body fat. "Abdominal fat is the fat distributed within the belly, surrounding the organs of the belly," he said. "This fat depot is called visceral fat because it is within the viscera (organs) of the body."
Blaha pointed to a gap in how BMI is commonly used. "It is becoming more recognized that BMI is not a great measure of metabolic and cardiovascular risk, [and] BMI is not a great measure of abdominal or visceral fat," he told Healthline. "Waist circumference and waist-to-hip ratio are good measures of abdominal/visceral fat. When added to BMI, they provide a much better assessment of body composition."
He also addressed what the findings mean for people who do not fall into the obesity category by BMI. "It is important to know that your weight or your BMI is not the end [of] the story," Blaha said. "Even if you do not have obesity by BMI (i.e., >30 mg/kg2), you may still have considerable abdominal/visceral fat that places you at higher metabolic and cardiovascular risk."
Blaha described the broader goal of the research. "The composition of your body matters, not just the weight," he said. "Our general goal will be to optimize lean body mass while reducing the amount of unhealthy abdominal or visceral fat."
BMI is calculated using a person's height and weight and has been widely used to determine whether a person's weight poses health risks. The study suggests that adding waist measurements to that assessment could give patients and doctors a clearer picture of cardiovascular danger, particularly for people who might appear to be at a normal weight by standard measures.