Development and validation of anthropometric predictive equations that estimate the total body water and fat-free mass in Tunisian adults.

OBJECTIVE: To develop and validate equations that estimate total body water (TBW) and fat-free mass (FFM) in adults using anthropometric measurements. METHODS: A cross-sectional study was conducted among 178 adults (77 men and 101 women; aged 18-59 years). Participants were distributed by sex and age groups, and then randomly assigned to equal two groups; the development (n = 89) and the validation (n = 89). The anthropometric measurements included height and weight. The deuterium dilution technique (DDT) estimated TBW and FFM. Linear regression models were used with the TBW and FFM as the dependent variable, and height and weight as the independent variables. Cross-validation was performed by Bland and Altman plot, and the new anthropometric equations were developed. RESULTS: In the validation sample, the developed equations had high R2 of 94.4 for both TBW and FFM in all age groups, and low standard errors (RMSE: 1.80 kg for TBW and 2.44 kg for FFM). The pure error was 2.03 for the TBW equation and 2.71 for the FFM equation. The Bland-Altman plot illustrated the good level of concordance between the TBW and FFM predicted by the new equations as determined by DDT. The following developed equations showed a better agreement with the DDT: [Formula: see text]; [Formula: see text]. CONCLUSION: In this study, we developed and validated prediction equations for the estimation of TBW and FFM from DDT in healthy adult Tunisian population. The newly anthropometric prediction equations seem to be the most accurate for Tunisian adult.

Relevance of body mass index and bioelectrical impedance analysis vs. deuterium dilution technique to assess excess of fat among young adults.

Our study aimed to assess the nutritional status by using body composition among young Tunisian adults through three measurement methods: body mass index (BMI), bioelectrical impedance analysis (BIA) and deuterium oxide dilution technique (2H2O) and to determine the accuracy of BMI and BIA in order to evaluate the overweight and obesity among young adults in Tunisia. Our study involved 144 young adults. Anthropometric parameters were measured. The fat mass percentage (%FM) was determined by 2H2O and BIA techniques. The analysis of deuterium enrichment was performed using a Fourier transform infrared spectrophotometer (FTIR). According to BMI, 26.4% of subjects were overweight and 5.5% were obese. The mean of %FM estimated by BIA was significantly higher than that determined by 2H2O (29.7 ± 7.7 vs. 26.3 ± 10.6, p < .0001). Consequently, the prevalence of overweight and obesity assessed by BIA was significantly higher than by 2H2O (51.4% vs. 34%, p < .0001). Using BMI, the prevalence of overweight and obesity was similar to that estimated by 2H2O (31.9% vs. 34%, p = 0.544). Compared to 2H2O, BIA overestimates the prevalence of overweight and obesity in young adults. On the other hand, the BMI showed an interesting correlation with the %FM determined by 2H2O.

Physical Activity Level Assessed by Accelerometer and PAQ-C in Tunisian Children.

BACKGROUND: Physical activity (PA) is an important agent in the prevention of chronic diseases such as obesity. OBJECTIVES: To provide preliminary data on PA among school children and to correlate the PA with weight status. MATERIAL AND METHODS: A total of 40 children aged between 8 and 11 years and attending Tunisian schools were recruited. The body composition was determined by using the deuterium oxide dilution technique. PA was determined by the PAQ-C (PA Questionnaire for Older Children). An objective monitoring of PA and sedentary time was achieved by using ActiGraph GT3X + accelerometers. RESULTS: PAQ-C data demonstrate that 20% of the sample had light PA levels and 80% had moderate PA levels. Times spent in sedentary (62.37%) and light (30.80%) activities were higher than that spent in moderate and vigorous (6.83%) activities. Furthermore, almost half of the sample spent more than 60 min per day in moderate-to-vigorous intensity PA (MVPA). The average MVPA was significantly higher in normal weight than overweight and obese groups (67.68 ± 20.98 vs. 49.07 ± 19.09, p = 0.007). The proportion of overweight children who spent more than 60 min per day in MVPA was significantly higher than that of normal-weight (60.9 vs. 29.4%; p = 0.049). CONCLUSION: This study indicates that half of school children comply with the health-based guidelines for PA and sedentary behavior. Our findings also suggest that obesity was associated with decrease in PA in Tunisian children.