Skeletal muscle mass reference curves for children and adolescents.

BACKGROUND: Skeletal muscle is key to motor development and represents a major metabolic end organ that aids glycaemic regulation. OBJECTIVES: To create gender-specific reference curves for fat-free mass (FFM) and appendicular (limb) skeletal muscle mass (SMMa) in children and adolescents. To examine the muscle-to-fat ratio in relation to body mass index (BMI) for age and gender. METHODS: Body composition was measured by segmental bioelectrical impedance (BIA, Tanita BC418) in 1985 Caucasian children aged 5-18.8 years. Skeletal muscle mass data from the four limbs were used to derive smoothed centile curves and the muscle-to-fat ratio. RESULTS: The centile curves illustrate the developmental patterns of %FFM and SMMa. While the %FFM curves differ markedly between boys and girls, the SMMa (kg), %SMMa and %SMMa/FFM show some similarities in shape and variance, together with some gender-specific characteristics. Existing BMI curves do not reveal these gender differences. Muscle-to-fat ratio showed a very wide range with means differing between boys and girls and across fifths of BMI z-score. CONCLUSIONS: BIA assessment of %FFM and SMMa represents a significant advance in nutritional assessment since these body composition components are associated with metabolic health. Muscle-to-fat ratio has the potential to provide a better index of future metabolic health.

Family-based behavioural management of childhood obesity: service evaluation of a group programme run in a community setting in the United Kingdom.

A service evaluation of a pilot of a family-based behavioural management group programme for childhood obesity was conducted in a community setting in the United Kingdom. A total of 17 families with children aged 7.5-14 years completed the programme, which was delivered in 15 sessions over 6 months. Behavioural and psychological measures and age- and sex-adjusted z-body mass index (BMI) were assessed before and after programme. z-BMI was maintained. There was a significant increase in the amount of high-fibre foods and a decrease in the amount of low-fibre foods consumed and in sedentary behaviours. There were significant decreases in depression, abnormal dieting behaviour and bulimia and food preoccupation, and an increase in self-worth related to physical appearance. These positive behavioural and psychological changes suggest that this is a promising programme.

Comparison of children's body fatness between two contrasting income groups: contribution of height difference.

OBJECTIVE: To compare measures of growth and body fatness (body mass index (BMI) and % body fat) in children from two contrasting income backgrounds and to examine the contribution of height difference to these measures. DESIGN: Cross-sectional study. SETTING: Schools in inner East London ('low income') and West London, Hertfordshire and Cambridgeshire ('high income'), UK. PARTICIPANTS: A total of 2298 children aged 5-14 years. MAIN OUTCOME MEASURES: Height, weight, BMI (weight per height(2)) and percentage body fat (%BF, by bioelectrical impedance analysis). RESULTS: Children from the 'lower income' background were significantly shorter, heavier and fatter (%BF) with a higher BMI for their age compared with those from a 'higher income' background. Prevalence of overweight/obesity was greater in the 'lower income' group children, assessed on the basis of BMI, and this income group difference was magnified when based on %BF (overfat/obese). Irrespective of the assessment tool used, overweight/overfat/obese children as a group were significantly taller for their age compared with children categorized as normal weight/normal fat. Despite the overfat/obese children being taller for their age, an 'income group' difference in height remained within this category. CONCLUSION: These findings confirm the income group influence on obesity prevalence. They also illustrate that BMI underestimates the true number of children having excess body fat, particularly in 'low income' children. Exactly why BMI seems to function differently along income group divisions in unclear, but a shorter height-for-age of the 'lower income' group children could be one explanation. These findings raise important questions about the causes and consequences of obesity in children from 'lower income' backgrounds.