The study examined the mortality risk of more than 6,000 Americans aged 18-65 years over a nine-year span using data from the Third National Health and Nutrition Examination Survey (NHANES III).

Researchers compared metabolically normal obese people with those who had multiple metabolic risk factors known to increase one’s risk for early mortality. Surprisingly, although both groups were at elevated mortality risk, there were no significant differences in the mortality risk between the groups.

“Our findings challenge the idea of a ‘healthy’ obese person,” says study lead Jennifer Kuk, an Assistant Professor in York’s School of Kinesiology & Health Science. “It doesn’t matter if you currently have no other medical problems. You are still at a similar risk level as someone who has the classic disease states triggered by obesity, such as diabetes, high blood pressure, or cardiovascular problems.”

For the purposes of the study, obesity is classified as anyone with a body mass index (BMI) of over 30. BMI is a measure of body fat based on height and weight that applies to adults. A normal BMI is between 18.5 and 24.9.

Respondents were defined as metabolically normal or abnormal based on measures of blood pressure, cholesterol, blood glucose, and triglycerides. Only 1.3 percent of respondents were classified as obese but metabolically normal.

“It’s important to note that metabolically-normal obesity is an extremely rare subtype, but when it does occur, treatment is absolutely necessary,” says Kuk. “We already know that in addition to diabetes and heart disease, obese individuals are also more likely to die from trauma and have cancer diagnosed at more advanced stages. This research reinforces the seriousness of this condition, and highlights the need for both treatment and prevention,” she says.

The study, “Are Metabolically Normal but Obese Individuals at Lower Risk for All-Cause Mortality?” appears in the December issue of Diabetes Care, published by the American Diabetes Association. It is co-authored by Chris Ardern, an assistant professor in York’s School of Kinesiology & Health Science.

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Media Contact:

Melissa Hughes, Media Relations, York University, 416 736 2100 x 22097, mehughes@yorku.ca