Apple-shaped but not obese? Don’t be smug!

People whose body mass index is considered normal and healthy may want to think twice about that designation if their waist-to-hip ratio is more suggestive of an apple than a pear, a new study from the Mayo Clinic finds.

Normal-weight Americans with an accumulation of fat around the middle were more likely to die of heart disease, and of any other cause, during a 14-year study period than were people whose BMI categorized them as obese but who were more pear-shaped. In fact, they had the highest risk of cardiovascular death of all the categories, including people whose BMIs identified them as overweight or obese.

The latest research was presented this week at the European Society of Cardiology meeting in Munich, Germany by Mayo cardiologist Dr. Francisco Lopez-Jimenez, lead author of the study. It involved 12,785 American adults with an average age of 44 who were categorized according to two so-called anthropometric measures: body mass index (BMI), the most widely used measure of obesity in biomedical research, and waist-to-hip ratio, a measure that has come into practice more recently.

“The combination of central distribution of fat and normal weight by BMI yields the highest mortality risk of all combinations using BMI and fat-distribution categories,” the authors concluded.

Compared with normal-weight people with pear-shaped waist-to-hip ratios, those with “normal healthy” BMI and thicker middles were more than twice as likely to die of any cause and 2.75 times more likely to die of cardiovascular disease during the 14-year study period, the study found.

Compared with the healthiest group -- those with a BMI in the normal range and a pear-shaped body type -- people who were obese by BMI standards but whose waist-to-hip ratio put them in the pear-shaped category were just a little less than twice as likely to die of cardiovascular disease. In other words, it’s far more dangerous to be apple-shaped than to be obese.

“You’re talking about a magnitude of risk that is quite significant,” said Dr. Lopez-Jimenez, who likened the added cardiovascular risk of having an apple-shaped figure to that of smoking tobacco or having Type 2 diabetes.

How to compare pears and apples? In this study, men who had a waist measuring more than 90% the size of their hips, and women whose waists were larger than 85% of their hip size, were in the danger zone: Their fat distribution clusters around the middle. For a healthier, pear-like fat distribution, a woman with 35-inch hips should have a waist smaller than 29.75 inches. A man with a circumference of 38 at the hips should have a waist circumference smaller than 34.2 inches.

Waist-to-hip ratio is heavily influenced by genetics as well as diet. But experts have long known that exercise can be a powerful influence on improving waist-to-hip ratio, even when it does not budge BMI. Similarly, adding sedentary behavior to the advancement of age can readily turn a pear into an apple.

In an interview, Lopez-Jimenez said the study should help physicians refine their guidance to patients who want to understand their personal risk of heart disease and stroke. BMI, said Lopez-Jimenez, is “not a good measure” of an individual patient’s risk, and “not a good measure of fatness either.” But a dangerous waist-to-hip ratio -- a measurement that is easily performed by doctors or patients -- could prompt a physician to recommend a boost in exercise and more careful eating.

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