Bioelectrical Vector Analysis in Obese Adolescents

Abstract

Objective: To evaluate the hydration of obese and non-obese adolescents by vectorial bioimpedance analysis, in addition to verifying the associations between obesity and bioelectrical impedance vectorial analysis (BIVA) parameters. Methods: A cross-sectional study with adolescents between 14 and 18 years old (n=489, 300 boys and 189 girls). Electric bioimpedance (BIA; Quantum_II, RJL system, Rome, Italy) provided resistance and reactance parameters to calculate phase angle (PA), fat-free mass (FFM) and body fat (%BF). The confidence ellipses were compared, and the construction of the tolerance ellipses allowed individual and qualitative evaluation of the vectors and classification in dehydrated, normohydrated and hyperhydrated. Results: 78 obese and 411 eutrophic adolescents participated. Resistance (p<0.001) and reactance (p<0.001) and their normalization by stature (p<0.001) were reduced in the obese, whereas the PA was higher (p=0.003). %BF was 11.3% higher in obese adolescents. The main vector of the obese, both male (D=1.38; p<0.001) and female (D=1.49; p<0.001), indicated greater hydration. The ellipse of tolerance of the total sample showed that 25 (32.1%) were hyperhydrated and 02 (2.6%) vectors positioned in the sense of dehydration. A total of 17 (53.2%) girls and 16 (34.8%) boys were hyperhydrated. Logistic regression showed an inverse relation of BMI with resistance (p<0.001), reactance (p<0.001) and both normalized by stature. Adolescents with increased PA (p<0.001) were twice as likely to present obesity. Conclusions: Obese adolescents were hyperhydrated and there was an inverse relationship of BMI with resistance and direct with PA.

Bioelectrical Impedance Analysis (BIA)- Derived Phase Angle in Children and Adolescents: A Systematic Review

“…Another major issue is the differences in sex. In line with the fact that PhA is greater in male than female adults (1,5,17,31), a few studies have indicated that PhA was higher in male than female teenagers by around 7%-10% (1,2,14,22,24,32,37), with similar findings also in adolescent athletes (30,41), and only 1 exception (34). There is less consistent evidence for younger subjects (Table 1); in early adolescence, a slightly greater PhA was reported in males than females (2,24,25,32), while little or no significant differences emerged in children in 3 studies (1,2,35).…”

“…In children/adolescent pooled, 1 study (1) showed that PhA tended to increase with BMI in either sex, while another one (23) found similar values of PhA in participants with obesity compared to controls. PhA was also higher in participants with obesity compared to controls in both adolescents (37) and 8 years old children (35,36) (Table 1).…”

“…Differences in PhA depending on BMI have evaluated defining overweight and obesity using either BMI as such (1,36) or BMI Z‐score (23,35,37,38).…”

“…In light of the high worldwide prevalence of overweight/obesity observed in the first 2 decades of life (44), it is quite surprising that there are only a few studies in children/adolescents on the relationships of PhA with BMI or BC. Four studies found an increase of PhA in subjects with higher BMI or BMI Z‐score (1,35–37), whereas another one found no difference between adolescents with obesity and controls (23). PhA also correlated with BMI in normal‐weight adolescent athletes, possibly because of increased muscle tissue and maturation (1,30).…”

Phase Angle as a Potential Screening Tool in Adults with Metabolic Diseases in Clinical Practice: A Systematic Review

“…Studies reported that obese subjects had a higher PhA in comparison with eutrophic subjects (6.9 ± 0.9° vs. 6.5 ± 0.8°; p = 0.003) [ 17 ]. Table 1 summarizes data from a multicenter clinical study of 217 individuals, showing a decrease in PhA with respect to age in type 2 diabetes mellitus (T2D) subjects compared with the control group [ 18 ].…”