Physiological and environmental factors associated with central fat distribution in pubertal girls

The aim of the work was to determine a degree of explanation of the variation of central fat distribution described by the waist-to-height ratio (WHtR) and waist circumference (WC) by both environmental and biological factors, including hormonal ones. The authors also intended to define the factors which are connected with a risk of abdominal obesity in girls. The study material includes a cross-sectional sample of 297 girls aged 9–16 years, examined in sport and regular schools in Cracow, Poland. Direct anthropometric measurements were done, breast development was assessed (Tanner stage) and leptin and ghrelin concentration in blood serum was estimated (by RIA method). The girls’ lifestyles and socio-economic status were investigated through survey questionnaires. The stepwise descending regression method was applied to evaluate a degree of WC, WHtR and BMI variation explanation. A logistic regression analysis was conducted to indicate factors connected with a risk of abdominal obesity (WHtR ³ 0.50) by calculating odds ratio (OR) and 95% confidence interval (CI). Variation of WC and WHtR was explained in, respectively, 53% and 44% by biological factors i.e. age, body height, the Tanner stage and blood serum leptin and ghrelin concentration as well as by environmental factors i.e. obesity prevalence in fathers and the girls’ high physical activity. Variation of BMI was explained in 56% by a similar set of variables, excluding the level of physical activity. The biological factors were the highest determinants of an adipose tissue distribution type in the girls. Besides biological factors a significant role was also played by the environmental ones: obesity prevalence in fathers and high level of physical activity. The waist to height ratio seemed to be a more sensitive identifier of environmental behaviours than the general adiposity index.

Association of the physical activity with leptin blood serum level, body mass indices and obesity in schoolgirls

Decreased physical activity is undoubtedly significantly associated with obesity. Similarly, the proper hormones secretion, the proper weight and body development. The aim of this study was to investigate the relationship between body mass composition and leptin concentration in relation to the degree of physical activity expressed in MET-h/week (metabolic equivalent per week). The study included 59 girls, aged 9-16 years (12.55±1.67) and divided into two groups: 1) PA: a physically active group of 29 girls and 2) PI: a group of 30 physically inactive girls. In all, physical activity was assessed using modified questionnaire concerning "activity for adolescents" and expressed in MET-h/week. Serum blood leptin concentrations in fasting girls were determined by RIA. Anthropometric parameters were measured and fatness indices calculated (BMI, SF, WHtR). Body composition (%BF, FM, FFM) was assessed using bioelectrical impedance analysis method (BIA). Statistical analysis showed significant differences between groups of PA and PI concerning values of BMI, WHtR, %BF, WC and MET-h/week as well as in leptin concentrations. In both groups of girls negative correlations between physical activity measured in MET and leptin concentrations and in WHtR were observed. The concentration of leptin was directly proportional to the degree of body fat and to the body composition expressed by BMI, WHtR, log SF, WC and %BF, FM and FFM, respectively. Increased physical activity was associated with lower body fat ratios and WHtR, BMI, WC, %BF, but did not affect significantly the changes in the values of log SF, FM and FFM. Higher values of BMI, WHtR and WC can provide not only a greater risk of obesity in general, but also cause excessive accumulation of fat in the central part of the body (abdominal obesity).