Body Composition with iDXA in Obese Subjects With and Without Metabolic Syndrome
Obesity has a major impact on public health and health-related expenses. Increased fat mass and its regional distribution, especially in the abdomen, are important predictors of the risk of cardiovascular disease and type-2 diabetes, diseases prevalent in individuals with a complex of metabolic risk factors referred to as the metabolic syndrome.
This study was approved by the Cedars Sinai Medical Center IRB. Sixty young (age 31.7 (6.9) years), obese subjects (33 females, 27 males) took part in an 8-month weight loss reality TV show. Fourteen participants received 3 months of televised “boot-camp” diet and exercise instruction and monetary incentives; thirty-six received only an intensive three-day diet and exercise seminar and weekly phone follow-up with no trainers or food services and negligible monetary awards; ten alternates received no instructions and were not invited back for the final assessment at 8-months. In addition to weight, blood pressure, anthropometric variables (waist circumference, hip circumference, waist/hip ratio), a number of metabolic variables (fasting glucose, high density lipoproteins (HDL), triglycerides), and body composition variables (android %fat, gynoid %fat, android/gynoid %fat ratio, trunk %fat, and total body %fat and %lean) were recorded at baseline and eight months later at the conclusion of the fitness program.
Body composition variables were calculated automatically by dual-energy x-ray absorptiometry (Lunar iDXA, GE Healthcare). Subjects whose supine body width exceeded the dimensions of the scan window were measured using the iDXA MirrorImageTM application (Figure 1a), which automatically calculates total body (TB) results by doubling the half-body values. Previous studies have shown that this doubling method provides an accurate estimate of TB results [1,2]. The android region included …