[Measurement of body fat mass in vivo: from two-compartment techniques to neutron activation analysis and DXA]

Valoración del riesgo cardiometabólico determinado por variables antropometricas en niños escolares con diversidad étnica

El aumento progresivo de la obesidad en la población escolar chilena es preocupante, los niños mapuches, corren un riesgo alto de ser obesos, debido a la rápida transculturación y el acceso deficiente a información de salud pública. El propósito del estudio fue comparar variables antropometricas y su relación con el riesgo cardiometabólico en niños Mapuches y no-Mapuches, pertenecientes a colegios rurales de la IX Región de Chile. Se evaluaron 239 escolares (118 niñas y 121 niños) entre 6 y 12 años, pertenecientes a 3 colegios de rurales de la comuna de Cholchol, Imperial y Galvarino de la región de la Araucanía Chile, perteneciendo 177 escolares a la etnia mapuche, participaron de la investigación de forma voluntaria. Se recolectaron datos respecto a descendencia étnica (mapuche, no mapuche), edad, peso, talla, circunferencia cintura (CC), relación cintura estatura (RCE) y el índice de masa corporal (IMC). En la comparación por sexo y etnia no existieron diferencias significativas (p>0,05). Las variables Antropométricas de peso, CC, RCE, IMC fueron mayores en los sujetos con obesidad y presentaron significancia (p<0.001). El IMC presentó elevada correlación con el CC y presentó significancia (p<0,001). El resultado de la correlación de variables en población Mapuche del IMC con el CC fue mayor (0,909, p<0,001), en comparación a los no-Mapuches. En esta investigación reportó una elevada prevalencia de malnutrición por exceso 43,9% del grupo total estudiado y una alta relación entre el IMC, el CC y la RCE, siendo mayor está en los niños con etnia mapuche.

Predictive Capacity and Cutoff Value of Waist-to-Height Ratio in the Incidence of Metabolic Syndrome

The purpose of this study was to compare the predictive ability of waist-to-height ratio (WHtR) compared with other anthropometric indicators in the incidence of metabolic syndrome (MetS) and to propose cutoff values for its early detection in nursing practice. A longitudinal cohort study was conducted on a sample of 630 workers (137 exposed and 493 nonexposed), free of MetS at baseline. WHtR was compared with body mass index (BMI), waist circumference (WC), and the percentage of body fat (BF%). In the Cox regression, the adjusted values of hazard ratio (HR) were 5.4 (confidence interval [CI] = [3.1, 9.5]) for WHtR and 7.4 (CI = [3.7, 14.9]) for components of MetS. WHtR obtained the largest area under the curve 0.82 (CI = [0.76, 0.88]), and with a cutoff value of 0.54, values were obtained for sensitivity (70%) and specificity (77%). WHtR was the best predictor of incidence of MetS, with a cutoff value of 0.54. Nursing can improve the early detection of MetS by measuring WHtR.

A simple equation to estimate body fat percentage in children with overweightness or obesity: a retrospective study

Background

Dual-energy X-ray absorptiometry (DXA) provides separate measurements of fat mass, fat-free mass and bone mass, and is a quick, accurate, and safe technique, yet one that is not readily available in routine clinical practice. Consequently, we aimed to develop statistical formulas to predict fat mass (%) and fat mass index (FMI) with simple parameters (age, sex, weight and height).

Methods

We conducted a retrospective observational cross-sectional study in 416 overweight or obese patients aged 4–18 years that involved assessing adiposity by DXA (fat mass percentage and FMI), body mass index (BMI), sex and age. We randomly divided the sample into two parts (construction and validation). In the construction sample, we developed formulas to predict fat mass and FMI using linear multiple regression models. The formulas were validated in the other sample, calculating the intraclass correlation coefficient via bootstrapping.

Results

The fat mass percentage formula had a coefficient of determination of 0.65. This value was 0.86 for FMI. In the validation, the constructed formulas had an intraclass correlation coefficient of 0.77 for fat mass percentage and 0.92 for FMI.

Conclusions

Our predictive formulas accurately predicted fat mass and FMI with simple parameters (BMI, sex and age) in children with overweight and obesity. The proposed methodology could be applied in other fields. Further studies are needed to externally validate these formulas.

The usefulness of densitometry as a method of assessing the nutritional status of athletes. Comparison with body mass index

The body mass index (BMI) is used to assess nutritional status. The result in athletes may be overestimated due to increase in muscle mass.

OBJECTIVE

To assess the usefulness of fat mass index (FMI) and lean mass index (LMI) determination as indicators of nutritional status and to compare the results with BMI.

MATERIAL AND METHODS

We studied 28 amateur rugby players, male. After being subjected to whole body densitometry by dual X-ray absorptiometry, we determined fat and lean body mass together with other parameters. FMI (fat in kg/height in meters(2)), LMI (lean in kg/height in meters(2)) and appendicular muscle mass index (AMMI, arms and legs musculature in kg/height in meters(2)) were calculated.

RESULTS

Using BMI, 18 players were overweight and 4 obese type I. Considering FMI, 7 of them had normal values and high LMI and AMMI, one of them changed from overweight to obese and another one from obese to overweight. Of the 6 players with normal BMI, one of them showed fat excess and another one fat defect. The results changed the assessment of nutritional status in 39% of players.

CONCLUSIONS

Although BMI is an appropriate parameter in general population for the assessment of nutritional status, in athletes should be taken into account fat and muscle body percentage and their corresponding indexes. The whole body densitometry appears to be a simple and reliable technique for this purpose.