Muscle-to-Fat Ratio for Predicting Metabolic Syndrome Components in Children with Overweight and Obesity.

Background: Pediatric obesity has been linked to the components of metabolic syndrome (MetS: abdominal obesity, atherogenic dyslipidemia, elevated blood pressure, and insulin resistance). Data on the role of muscle mass in the development of MetS are sparse. We explored the interaction between the muscle-to-fat ratio (MFR) and MetS components in children with overweight or obesity. Methods: An observational study of 210 pediatric subjects (88 boys, mean age [±standard deviation (SD)] 11.9 ± 3.1 years, BMI z-score range 1.036-3.140) from January 2018 to January 2021. Body composition was measured by bioelectrical impedance analysis (Tanita MC-780 MA and GMON Professional Software), and MFR z-scores were calculated. Results: The 148 subjects (70%) who had MetS components were older (p = 0.008), had lower socioeconomic positions, higher triglyceride/high-density lipoprotein-cholesterol ratios, fat percentages (FATP), truncal FATPs (TRFATPs), and lower MFR z-scores (p < 0.001 for all parameters) than those without MetS components. The correlation between the MFR z-score and the BMI z-score was stronger in subjects with obesity than in subjects with overweight (r = -0.556 vs. r = -0.440, p < 0.001 for both). The risk for MetS components increased by 1.4 for every 3% increase in FATP or TRFATP [odds ratio (OR) = 1.4, confidence interval ([CI] 1.20, 1.64), p < 0.001]. The risk for MetS components was tripled for every 1 SD decrease in MFR z-scores [OR = 3.3, CI (1.74, 6.27), p < 0.001]. Conclusions: Given the strong predictive value of the MFR z-score in the development of early-onset MetS components, preventive strategies should apply interventions for improving the body composition parameters of both adiposity and muscle.

Beyond Body Mass Index - Body Composition Assessment by Bioimpedance in Routine Endocrine Practice.

OBJECTIVE: To explore the body composition of pediatric patients referred for endocrine evaluation. METHODS: This real-life observational study conducted between January 2018 and January 2020 included 10 001 clinic visits of 3500 children and adolescents; first visits of 5 to 18-year-old patients were included. Anthropometric data, blood pressure levels, pubertal status, and bioelectrical impedance analysis (BIA, Tanita MC-780 MA) were extracted from medical files. Excluded from the analysis were patients participating in other studies. RESULTS: A total of 1001 patients (48% boys, mean age 11.3 ± 3.4 years, 33.5% prepubertal) were included. Mean anthropometric z-scores were normal and similar for boys and girls. Sex differences in body composition were as follows: boys had lower fat percentage, lower truncal fat percentage, higher appendicular skeletal muscle mass, and a higher muscle-to-fat ratio (MFR) than girls (P < .001 for all). MFR correlated with body mass index-standard deviation scores (BMI-SDS) in overweight/obese patients (r = -0.558, P < .001), although not in underweight patients. Systolic blood pressure (SBP) correlated with BMI-SDS in overweight/obese patients (r = 0.262, P < .001), although not in underweight patients. Diastolic blood pressure (DBP) did not correlate with BMI-SDS in either group of extreme weight status. MFR correlated with SBP and DBP in overweight/obese patients (r = -0.230, P < .001 and r = -0.141, P = .018, respectively) as well as in underweight patients (r = 0.331, P < .001 and r = 0.264, P = .005, respectively). CONCLUSIONS: Our findings support BIA for a more refined characterization of patients referred for endocrine evaluation than BMI-SDS. MFR may be a better surrogate marker of blood pressure levels than BMI-SDS in both underweight and overweight/obese pediatric patients.