EVALUATION OF METABOLIC PARAMETERS AND BODY COMPOSITION IN ADOLESCENTS WITH VARIOUS DEGREES OF OBESITY USING BIOELECTRICAL IMPEDANCE ANALYSIS

The rapid rise in the prevalence of obesity among children and adolescents has emerged as one of the most critical challenges in modern pediatrics and pediatric endocrinology. Consequently, implementing highly accurate, non-invasive methods to evaluate body composition – specifically multi-frequency bioelectrical impedance analysis (InBody technology) – is of paramount clinical relevance. The aim – to analyze in detail metabolic parameters and body composition in adolescents aged 11-16 with hypothalamic dysfunction (HD) and varying degrees of obesity, using InBody technology. Materials and methods. The study evaluated 63 children with hypothalamic dysfunction aged 11-16 (mean age: 14.5±1.8 years). The primary group comprised 42 overweight and obese adolescents (21 boys, 21 girls). The control group consisted of 21 healthy peers with normal BMI (11 boys, 10 girls). Inclusion criteria: presence of signed informed consent, verified diagnosis of hypothalamic dysfunction with overweight or obesity or confirmed normal weight (for the control group),as well as the absence of any acute inflammatory or infectious diseases for at least the last month. Exclusion criteria: severe comorbid somatic diseases in stages of subcompensation or decompensation; use of medications with a direct impact on metabolism or water-salt balance (e.g., systemic steroids or diuretics); and presence of metal implants or pacemakers, which represent absolute contraindications for bioelectrical impedance analysis. Body composition was assessed by bioelectrical impedance analysis (BIA) on an InBody analyzer following a standard morning fasting protocol. The evaluated parameters included total body water (TBW), protein mass, mineral mass, skeletal muscle mass (SMM), fat mass (BFM), percent body fat (PBF), extracellular water-to-total body water ratio (ECW/TBW), and waist-to-hip ratio (WHR). Statistical processing and correlation analyses (Pearson and Spearman) were performed using Statistica and Excel.The study protocol was approved by the Local Ethics Committee of the participating institution (No. 48/6-KE dated March 25, 2024). The Biomedical Ethics Commission of the State Institution "V.P. Komisarenko Institute of Endocrinology and Metabolism of the National Academy of Medical Sciences of Ukraine" found no violations of moral or legal standards during the study. Informed consent was obtained from all participants and their parents. Results and discussion. Bioelectrical impedance analysis revealed a profound structural and metabolic reorganization of the body as obesity progressed. The dominant pathological process was intensive fat accumulation: body fat mass rose more than 5-fold from 12.36±5.15 kg in controls to 64.04 ±8.26 kg in patients with BMI > 40.0 kg/m2 (p < 0.01). Concurrently, percent body fat in the morbidly obese group reached 49.86 ± 2.90%, demonstrating that adipose tissue accounted for nearly half of the patient's total body weight. During the overweight stage and class I–II obesity, the adolescent body successfully adapted to the increased mechanical load by compensatorily increasing skeletal muscle mass (from 24.66 ±7.07 kg to 31.21 ±5.45 kg, p < 0.05), protein mass (from 8.85 ±2.37 kg to 11.36 ±1.79 kg, p < 0.05), and bone mineralization in response to weight-bearing stress. Correlation analysis confirmed moderate positive correlations between skeletal muscle mass, protein, and waist-to-hip ratio (r = +0.63 to +0.65) in these cohorts. However, once the BMI exceeded the 35.0-40.0 kg/m2 threshold, adaptive mechanisms and anabolic reserves became depleted. In the morbidly obese group, the correlation between BMI and fat-free mass parameters became negative: a moderate inverse correlation was observed between BMI and muscle mass (r = -0.46), protein (r = -0.44), and minerals (r = -0.56). Key insights were also gained from analyzing fluid compartments. The fluid distribution index (ECW/TBW) remained stable across all groups at 0.37-0.38, indicating that genetically determined water-salt balance regulation remains intact. Conclusions: The primary pathological driver of elevated BMI in children and adolescents is progressive lipophilia accompanied by an abdominal fat distribution pattern (WHR>1.0), establishing early risk factors for insulin resistance and cardiometabolic syndrome. The response of fat-free tissues to excess weight is biphasic: an initial phase of physiological compensatory hypertrophy of the muscular and skeletal systems (at BMI < 35.0 kg/m2) is followed by a phase of decompensation and the development of sarcopenic obesity (at BMI > 40.0 kg/m2). These findings highlight the clinical necessity of incorporating multi-frequency bioelectrical impedance analysis (InBody testing) into standard diagnostic protocols for pediatric overweight and obesity.