Belly fat increases the risk of death in people with coronary artery disease more than fat that accumulates elsewhere, a new study suggests.

The study in the May 10 issue of the Journal of the American College of Cardiology concluded that those with the most common form of heart disease and "central obesity" — measured by waist circumference and hip-to-waist ratio — had up to twice the risk of dying, after a review of studies on nearly 16,000 people in the U.S., Denmark, France and Korea.

Documenting waist circumference and hip-to-waist ratio in patients with coronary artery disease, regardless of their body mass index, could help, researchers suggest. (M. Spencer Green/Associated Press)

"Our data suggest waist circumference and hip-waist-ratio to be more reliable than body mass index in stratifying mortality risk in coronary artery disease patients," Dr. Thais Coutinho, the study's lead author and a cardiology fellow at Mayo Clinic and her co-authors concluded.

"These findings might have significant implications for clinical practice, because it is generally accepted that, if body mass index is normal, no further measures of obesity are necessary, and no lifestyle modifications to induce weight loss might be recommended."

The authors instead suggest that doctors document waist circumference and hip-to-waist ratio in patients with coronary artery disease, regardless of their BMI, with the aim of treatment recommending fat loss.

BMI measures weight in proportion to height without taking the distribution of fat into consideration, the researchers noted.

"What seems to be more important is how the fat is distributed on the body," Coutinho said.

Visceral or intra-abdominal fat surrounding the internal organs has been found to be more metabolically active, producing more changes in cholesterol, blood pressure and blood sugar compared with people who have fat mostly in the legs and buttocks, the researchers said.

In 2007, waist circumference became part of a preventive care list for family doctors in Canada — a checklist for physicians to use during checkups for adults by measuring the perimeter of a patient's waist and hip with a tape measure.