Prediction of body tissue distribution with multi-dimensional anthropometry

Prevalence of overweight and obesity is high and increasing worldwide. Recent evidence suggests that both lean and fat mass predict mortality in individuals with and without cardiovascular disease. This requires knowledge of individual tissue compartments,such as muscle and adipose tissue, and relies on accurate methods of body composition assessment. Since the accepted gold' standards for body composition estimation in vivo, such as magnetic resonance imaging and computer tomography (CT)are difficult to access in routine health care situations, it remains important to use anthropometry in the screening and diagnosis of health and nutritional status. Today, the validity of anthropometric variables for estimating regional body tissue distribution is largely unknown, especially with regard to the trunk region. In an attempt to contribute to the validation of techniques to estimate regional body composition four studies were carried out during this PhD project. The first study was designed to investigate whether simple anthropometric indexes, such as the body mass index (BMI) and the waist circumference, are appropriate measures of tissue distribution in elderly persons. The results indicate that single measurements of body weight and height or waist circumference are of limited use for assessing body tissue distribution in elderly individuals due to significant between subject variability. It was concluded that the assessment of health risk based on simple anthropometric indexes is susceptible to significant error in elderly persons, especially in the intermediate BMI ranges. The conclusion of the first study, that simple anthropometric indexes are insufficiently accurate to determine body tissue distribution, have prompted to ascertain whether regional lean and fat tissue can be predicted more accurately using a combination of anthropometric variables. The findings of the second study suggest that regional lean mass can be predicted with consistent accuracy in groups of young adults using anthropometric formulae, confirming its potential in assessing nutritional status. When using these prediction formulae in clinical practice, it should be kept in mind that estimation errors up to 14% may occur in certain individuals depending on the anatomical region of interest. The results of the third study indicate that fat distribution can be predicted accurately in young adults without proportional or systematic differences compared to the criterion method dual energy X-ray absorptiometry (DXA). This study also shows that defining fat distribution thresholds based on t-scores, by analogy with osteoporosis assessment, might prove itself a useful tool to detect abnormal fat distribution. The clinician needs to be aware that misclassification in a minority of subjects may still occur, in particular those with borderline values. Based on the conclusions of the two previous studies, the question was raised whether the criterion method DXA is a suitable assessment tool for estimating body tissue distribution. In order to determine the accuracy and precision of DXA, a validation study using CT was carried out in a sample of elderly persons. The findings of this fourth study confirm that DXA is significantly related to CT-derived tissue analogues. However, given the fact that they represent different quantitative and physiological body components, it is not recommended to use these variables interchangeably in clinical practice. It was also concluded that fat by DXA represents different adipose tissue depots in elderly men and women, suggesting that it is not an appropriate tool for assessing regional adipose tissue variability be

Publication year:2013

Keywords:BMI