Reliability and accuracy of segmental bioelectrical impedance analysis for assessing muscle and fat mass in older Europeans: a comparison with dual-energy X-ray absorptiometry.
ABSTRACT Segmental determination of muscle and fat mass (MM, FM) attains growing importance for judging effects of training and malnutrition in older people. This study evaluated the reliability and accuracy of segmental bioelectrical impedance analysis (sBIA) for use in older people. In 72 (40 men, 32 women) healthy elderly (mean age 69.0 ± 4.8 years), the MM and FM of right and left arm (RA, LA), right and left leg (RL, LL), and trunk were determined by sBIA (BC-418-MA, Tanita) and dual-energy X-ray absorptiometry (DXA) as a reference method. The sBIA provided in both sexes reliable values for limb and truncal MM and FM, except for MM of RL in women. The accuracy of sBIA displayed sex-specific bias. For MM, accurate values were noted for men's trunk and women's limbs (except LA). By contrast, MM was significantly underestimated in men's limbs by 6-18% and overestimated in women's LA (13%) and trunk (14%). Estimates of FM were accurate for men's arms as well as women's legs and trunk. However, FM was significantly overestimated in men's legs (34-37%) and trunk (60%), but underestimated in women's arms (27-35%). The proportional deviations of sBIA estimates from DXA values for limbs and trunk were significantly related to the respective MM or FM. The sBIA tends to underestimate MM in men and to overestimate in women. The reverse occurs for FM. The actual equations of the Tanita device may not completely represent the European older population and should be partly revised.
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ABSTRACT: Cirrhosis is a state of accelerated starvation with impaired protein synthesis. Increased rate of gluconeogenesis and alterations in skeletal muscle signaling pathways result in anabolic resistance and consequent loss of muscle mass or sarcopenia in cirrhosis. Late evening snack (LES) is an intervention to reduce the postabsorptive (fasting) phase with the potential to improve substrate utilization and reverse sarcopenia. Published reports were evaluated to examine the effect of LES on regulation of substrate utilization (short-term studies) and nutritional outcomes (long-term studies). PubMed, EMBASE, Google scholar and OVID databases were searched. All studies published on LES in cirrhosis were included. Studies that included few (n < 3) subjects and patients with hepatocellular carcinoma were excluded. Late evening snack decreased lipid oxidation and improved nitrogen balance, irrespective of the composition or type of formulation used. Daytime isocaloric isonitrogenous snacks did not have the metabolic or clinical benefit of LES. LES decreased skeletal muscle proteolysis. No studies have examined its effect on muscle protein synthesis. There was inconsistent translation into an increase in lean body or skeletal muscle mass. Improved quality of life occurs but decreased mortality or need for transplantation has not been reported. The optimal composition of LES has not been defined, but based on mechanistic considerations, a branched chain supplemented LES holds most promise. Late evening snack holds the most promise as an intervention to reverse anabolic resistance and sarcopenia of cirrhosis with improved quality of life in patients with cirrhosis. Long term benefit and improved survival need critical evaluation.Journal of Gastroenterology and Hepatology 03/2012; 27(3):430-41. DOI:10.1111/j.1440-1746.2011.06951.x · 3.63 Impact Factor
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ABSTRACT: Bioelectrical impedance analysis is a popular, noninvasive and practical method for assessment of body composition. The last decade has seen the development of impedance analyzers designed to assess the composition of body segments as well as the whole body. This review outlines the theoretical basis for segmental impedance analysis, validity and use in practice. Segmental impedance analysis tends to underestimate fat-free mass and overestimate fat mass when compared to reference techniques, although the magnitude of these differences can be small. Performance is improved with population-specific prediction equations; algorithms in-built into instrument firmware should not be relied upon. Prediction of whole-body composition from the sum of the individual segments, although theoretically preferable, shows little advantage over whole body wrist to ankle impedance approaches. Prediction of appendicular skeletal muscle mass, although promising, requires further research. The use of measured impedance data directly as indices of composition, rather than for prediction, has not found extensive application in nutritional research despite its success in other fields. Segmental bioimpedance techniques have advanced substantially in recent years due to availability of simple-to-use analyzers and simplified measurement protocols. The method has been well validated and increasingly adopted in nutritional and clinical practice. Segmental impedance, like conventional whole body impedance approaches, provides indirect prediction of body composition whose accuracy is yet to achieve that of reference techniques such as magnetic reference imaging. This lack of accuracy, however, is outweighed by the method's practicality of use in many settings.07/2012; 15(5):424-9. DOI:10.1097/MCO.0b013e328356b944