Influence of age and gender on fat mass, fat-free mass and skeletal muscle mass among Australian adults: the Australian diabetes, obesity and lifestyle study (AusDiab).

BACKGROUND: Bioelectrical impedance (BIA) represents a simple, inexpensive and non-invasive method that is often used to assess fat-mass (FM) and fat-free mass (FFM) in large population-based cohorts. OBJECTIVE: The aim of this study was to describe the reference ranges and examine the influence of age and gender on FM, FFM and skeletal muscle mass (SMM) as well as height-adjusted estimates of FM [fat mass index (FMI)], FFM [fat-free mass index (FFMI)] and SMM [SMM index (SMI)] in a national, population-based cohort of Australian adults. DESIGN AND PARTICIPANTS: The analytical sample included a total of 8,582 adults aged 25-91 years of Europid origin with complete data involved in the cross-sectional 1999-2000 Australian, Diabetes, Obesity and Lifestyle (AusDiab) Study. MEASUREMENTS: Bioelectrical impedance analysis was used to examine components of body composition. Demographic information was derived from a household interview. RESULTS: For both genders, FFM, SMM and SMI decreased linearly from the age of 25 years, with the exception that in men SMI was not related to age and FFM peaked at age 38 years before declining thereafter. The relative loss from peak values to ≥75 years in FFM (6-8%) and SMM (11-15%) was similar between men and women. For FM and FMI, there was a curvilinear relationship with age in both genders, but peak values were detected 6-7 years later in women with a similar relative loss thereafter. For FFMI there was no change with age in men and a modest increase in women. CONCLUSION: In Australian adults there is heterogeneity in the age of onset, pattern and magnitude of changes in the different measures of muscle and fat mass derived from BIA, but overall the age-related losses were similar between men and women.

A qualitative investigation into the opinions of adolescent females regarding their body image concerns and dieting practices in the Republic of Ireland (ROI).

The aim of this study was to investigate the opinions of female adolescents living in the ROI on issues relating to body image and dietary practice. A qualitative study was selected to enable the issues to be explored in depth. Sixteen focus groups were executed with adolescent females (n=124) aged 15-16 years. Data collection took place during class time in both rural and urban schools in the ROI. Data were analysed using a qualitative thematic methodology, namely framework analysis. High levels of body dissatisfaction existed and dieting was found to be prevalent. The influence of media celebrities was significant. The girls not only aspired to be like them in terms of physique but also followed their alleged dieting regimes in detail. Peers also influenced body dissatisfaction and dieting practices. Consequently, eating habits were altered to accommodate this quest for thinness with a tendency to skip main meals as part of the dieting practice while maintaining an unhealthy snacking pattern. The results are of concern as the adolescent females were utilising unhealthy methods of weight control such as skipping meals and fasting in their quest to obtain a thin physique. A slim body image was deemed important for peer acceptance; hence 'crash' dieting was in existence. This mindset and the resultant dietary practices may have negative health consequences during both adolescence and later life. School interventions targeting adolescent females and focusing on healthy eating and body image are therefore urgently required.