May Bioelectrical Impedance Analysis Method Be Used in Alternative to the Dual-Energy X-Ray Absorptiometry in the Assessment of Fat Mass and Fat-Free Mass in Patients with Obesity? Pros, Cons, and Perspectives

Excerpt

The World Health Organization has described obesity as one of the most blatantly visible, yet most neglected, public health problems [1]. A modern approach to obesity acknowledges the multifactorial determinants of weight gain and the health benefits to be derived from weight loss [2]. An important goal during weight loss is to maximize fat mass (FM) loss while preserving metabolically active fat-free mass (FFM) [3‐5]. A significant decrease in FFM may negatively affect the resting metabolic rate (RMR) [6], slow the rate of weight loss, and predispose to weight regain [7]. Therefore, to improve the quality assessment of weight loss, it is essential to assess FM and FFM. There are several available accurate techniques for the assessment of FM and FFM in normal-weight subjects, such as dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) [8]. A DXA scan has a very low error rate of 1–2%, compared with 5–15% for BIA; provides a rapid and non-invasive assessment of FM, FFM, and bone mineral density; does not require any specific preparation; and is considered to be the reference method in clinical research [9]. This is due to the advanced X-ray technology that leaves little guesswork and no extra calculations to provide accurate data. Nevertheless, DXA requires specialized radiology equipment and is expensive, and thus hardly feasible in routine clinical practice. Inversely, bioelectrical impedance analysis (BIA) represents a simple, non-invasive, low-cost device commonly used for FM and FFM assessment in clinical practice and research studies, through the resistance of the body to a small alternating current [10]. BIA uses predictive equations to calculate FFM. …