For people with coronary artery disease, including those with a "normal, healthy" body-mass index (or BMI), having even a little flubber around the middle is a bad omen, increasing the risk of death as much as smoking a pack of cigarettes a day or having very high cholesterol. But having a BMI in the "overweight" or "obese" category does not, by itself, imply a grim prognosis, says a new study.
The new research, published Monday in the Journal of the American College of Cardiology, makes clear that when it comes to body composition, it is better to be pear-shaped--carrying fat deposits in the hips, buttocks and thighs--than to be shaped like an apple, carrying excess fat around the middle. And it makes clear that for a patient with clogged or obstructed coronary arteries, a large waist circumference and high waist-to-hip ratio are better prognosticators of death than is his or her BMI, which is a poor measure.
The study, which culled data from more than 15,000 patients in the United States, Denmark, France and South Korea, finds that where one carries fat matters more than whether one carries a bit too much. And it casts new doubt on the value of the BMI as a comprehensive measure of an individual's health prospects. (You can read an in-depth critique published recently in the Los Angeles Times of BMI here.)
The study provides some new evidence to support the so-called "obesity paradox"--a cluster of findings suggesting that once diagnosed with heart disease, the patient who is overweight or obese is less likely to die than one who is at normal weight or below. "The association between fatness and mortality might rely more on measures of fat distribution than on the amount of body fat," the authors wrote.
But most with a high BMI should not take too much comfort from the study. Mayo Clinic cardiologist Thais Coutinho, the lead author of the study, said the study demonstrated that BMI is a poor bellwether of a cardiovascular patient's prognosis, in that even patients with BMIs in the normal healthy range were at high risk of dying if they had a spare tire. So, relying too heavily on BMI misses a lot of people who should whittle their waists to improve their health.
But those whose BMIs are between 25 and 29.9 (overweight) and above 30 (obese) are at high risk, too, if their midsections are larded with extra fat. A waist circumference above 35 inches for women and 40 for men is considered dangerous, and gets more dangerous with every added inch. Figuring out the waist to hip ratio requires a tape measure and the back of an envelope (ideally, it should be no more than 0.8 for women and 0.95 for men), but here's a calculator to check that too.