BMI misses where fat sits
A large new study says the size of a person's midsection is a better predictor of heart disease risk than body mass index alone. The findings were published in JACC, the flagship journal of the American College of Cardiology.
BMI is calculated by dividing weight in kilograms by height in meters squared. It has been the standard tool for defining overweight and obesity for decades. But BMI cannot show where fat is stored. Fat around the organs, called visceral fat, is linked to heart disease and diabetes. Fat just under the skin is less risky.
20 years of data
Researchers from the Cross Cohort Collaboration looked at more than 260,000 adults. They followed participants for an average of about 20 years. The study tracked waist circumference and waist-to-hip ratio along with BMI, then compared how well each measure predicted heart attacks, strokes, heart failure, atrial fibrillation, and related deaths.
The results were clear. Waist circumference and waist-to-hip ratio predicted cardiovascular risk better than BMI alone. Nearly one in five people with a normal BMI but a high waist-to-hip ratio had up to 50 percent higher risk for several heart conditions. Relying on BMI alone would have missed those people.
Why belly fat is dangerous
Inflammation appears to explain part of the danger. A separate analysis in the same research program found that higher waist measurements were linked to heart failure risk even when BMI looked normal. Systemic inflammation played a key role. About one-quarter to one-third of the link between abdominal fat and heart failure was explained by inflammation.
The authors say these simple measurements should be part of routine heart risk checks. Both can be done at home with a tape measure. The message from the study is straightforward: where fat sits on the body matters, and it matters more than the scale alone can show.