BackgroundThe body mass index (BMI) is a simple and widely utilized screening tool for obesity in children and adults. The purpose of this investigation was to evaluate if BMI could predict total fat mass (TFM) and percent body fat (%FAT) in a sample of overweight and obese children.MethodsIn this observational study, body composition was measured by dual energy x-ray absorptiometry (DXA) in 663 male and female overweight and obese children at baseline within a multidisciplinary, pediatric fitness clinic at an academic medical center. Univariate and multivariate regression analyses were conducted to evaluate whether BMI z-score (BMIz) predicts TFM or %FAT.ResultsThe BMIz, sex and age of subjects were identified as significant predictors for both TFM and %FAT. In subjects younger than 9 years, the BMIz was a weak to moderate predictor for both TFM (R2 = 0.03 for males and 0.26 for females) and %FAT (R2 = 0.22 for males and 0.38 for females). For subjects between 9 and 18 years, the BMIz was a strong predictor for TFM (R2 between 0.57 and 0.73) while BMIz remained only moderately predictive for %FAT (R2 between 0.22 and 0.42).ConclusionsThese findings advance the understanding of the utility and limitations of BMI in children and adolescents. In youth (9-18y), BMIz is a strong predictor for TFM, but a weaker predictor of relative body fat (%FAT). In children younger than 9y, BMIz is only a weak to moderate predictor for both TFM and %FAT. This study cautions the use of BMIz as a predictor of %FAT in children younger than 9 years.

Aim Little is known about inpatient probiotic and prebiotic consumption or beliefs, despite their increase in availability. Therefore, the purpose of this research was to assess inpatient knowledge, use and perceptions of probiotics and prebiotics. Methods All subjects were inpatients at two urban medical centres on general medical/surgical floors. Patients were randomly selected to complete a verbally administered questionnaire inquiring about probiotic and prebiotic knowledge, use and perceptions. Patient responses were recorded directly into Survey Monkey (Palo Alto, CA, USA) on a computer. Results Patients (n = 200) were 58% were women and 56% were Caucasian with a mean age of 56 years. More patients were familiar with the term ‘probiotic’ (43%) compared with ‘prebiotic’ (11%); however, only 20% and 7% could correctly define probiotics and prebiotics, respectively, from a list of responses. More patients were consuming probiotics (53%) than prebiotics (38%). The most common probiotic and prebiotic products consumed were yogurts (72%) and cereals/granola bars (55%), respectively. Patients believed probiotics and prebiotics most beneficial for ‘digestion or gut health’, but the most common reason to consume these products was ‘to taste or try’ (36% and 43%, respectively). Overall, patients believed probiotics and prebiotics to be safe; however, they also believed that health claims could only somewhat be trusted. Conclusions This research found that many patients are consuming probiotic and prebiotic products despite limited awareness of the true meaning of these terms. As probiotic and prebiotic use is more common, it is important that clinicians are aware of increased use and provide patients with recommendations based on recent research.

BackgroundThe age and sex standardized body mass index (BMIz) is a simple and widely utilized screening tool for obesity in children and adolescents. The purpose of this study was to evaluate the relationship between the BMIz trajectory versus the percent body fat (%FAT) trajectory, and if BMIz could predict significant changes in %FAT in a sample of obese children and adolescents.MethodsIn this longitudinal observational study, body composition was measured by dual energy x-ray absorptiometry (DXA) in obese children within a multidisciplinary pediatric fitness clinic at an academic medical center over a 3-year time period. Regression analyses were conducted to evaluate the association between changes in BMIz and changes in %FAT.ResultsBaseline assessment was obtained from 515 participants. The reduction observed in BMIz (2.20 to 2.08, p < 0.0001) correlated with the reduction in %FAT (38.5 to 35.8%, p < 0.05) in the first two years. The overall correlation between the slope in BMIz reduction versus %FAT reduction was moderate (r = 0.36, p < 0.0001) over the 3-year follow-up period. The sensitivity of BMIz changes for predicting a decrease in %FAT was acceptable (70, 95% CI: 61–78%), however the specificity was poor (42, 95% CI: 31–54%).ConclusionsThese findings advance the understanding of the utility and limitations of BMIz in children and adolescents. While BMIz may be sensitive to changes in adiposity, it is a weak predictor of these changes in total body fat (%FAT) due to the poor specificity. Therefore, clinicians must exercise caution when monitoring changes in a growing child’s body composition to avoid misclassifying or missing substantial change when utilizing BMIz alone.

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The COVID-19 pandemic has significantly altered children's daily routines. The health impacts of our obesogenic environment are exacerbated by COVID-19. Many clinicians have concerns that the lack of structured activity, increased stress and altered eating behaviors would lead to increases in adiposity in children. The present study examined changes in body composition as a result of the COVID-19 pandemic in pediatric patients in larger bodies and demonstrates significant increases in total body fat, percent body fat (%fat), and BMI z-score, as well as markers of insulin resistance. In this retrospective, longitudinal study, body composition was measured by dual energy x-ray absorptiometry (DXA) within a multidisciplinary pediatric fitness clinic at an academic medical center. Visit dates were categorized into Pre-COVID-19 (before 4/1/2020) and Peri-COVID-19 (on or after 4/1/2020). Linear mixed effects modeling was conducted to evaluate changes in clinical and laboratory outcomes from Pre- to Peri-COVID-19. Baseline assessment was obtained from 650 patients with higher BMI scores (52% male) with a mean (SD) age of 12.3 (3.2) years. The adjusted mean BMI z-score (BMIz) was significantly higher in the Peri-COVID-19 sample when compared to the Pre-COVID-19 samples (2.31 vs. 2.25, P < 0.0001) which can be attributed to greater total fat mass (TFM) of 93.0 (90.0-96.4) lbs. (P = 0.007) and %FAT of 40.2% (39.2-41.2) as compared to the Pre-COVID-19 patients. The COVID-19 pandemic influenced social determinants and lifestyle factors. Most notable changes observed were negative changes in physical activity and screen time. The need for social isolation in a pandemic has resulted in worsening obesity and its comorbidities, and pediatricians need to be aware of this issue. The COVID-19 pandemic exerts disproportionate burden on children and families, magnifying their vulnerability to changes in body composition and chronic disease risk.