News at Medicine - August 2010 - Method critical in accurate measurement of body fat

Method critical in accurate measurement of body fat
August 23, 2010
A new research paper from the laboratory of Dr. Guang Sun, Discipline of Medicine, recommends caution in determining the metabolic health of obese people, depending on the method used to measure body fat.
Doctoral student Jennifer Shea is first author on the paper, which was published Aug. 12 in journal Obesity and featured on MDLinx, an online resource for physicians and healthcare professionals to stay up to date with the latest research in the medical field. The paper is titled The Prevalence of Metabolically Healthy Obese Subjects Defined by BMI and Dual-Energy X-Ray Absorptiometry.

Ms. Shea explained that there is a close relationship between obesity and an abnormal metabolic profile, a group of risk factors that can raise the risk of heart disease and other health problems. A metabolic profile measures serum lipids, fasting sugar, insulin resistance, blood pressure and C-reactive protein, a protein found in the blood and synthesized by the liver in response to factors released by fat cells.

“Obesity is a primary risk factor for these metabolic abnormalities, however recent research has shown us that not all obese individuals display an abnormal metabolic profile,” she said. “Some obese individuals appear to be resistant to the development of obesity-related metabolic complications. Past studies have estimated that approximately 30 per cent of obese people are in fact metabolically healthy. However, these studies have all used body mass index (BMI) as a measure of obesity. We know from a past study in our lab that BMI is not the most accurate method to determine obesity. We therefore wanted to investigate the prevalence of metabolically healthy obese individuals using a more accurate reference method called dual-energy X-ray absorptiometry as a measure of adiposity.”

The new study, which considered six criteria to define metabolic health, discovered that the proportion of metabolically healthy obese people is even higher – about one-half.

“This study is important because it demonstrates that there are marked differences in the prevalence of metabolically healthy obese individuals, depending on the method used to measure obesity.”

Ms. Shea also said about 25 per cent of the normal weight population in this study had an abnormal metabolic profile, similar to what would normally be expected in overweight of obese people. “Because of this it is important that everyone be screened for metabolic markers.”

Ms. Shea has so far published seven papers in peer-reviewed journals with five as the first author and two as the second author. The other two authors of the present paper are Drs. Edward Randell and Guang Sun.