Relative Importance of Lean and Fat Mass on Bone Mineral Density in Iranian Children and Adolescents

Abstract

Background:Body weight is made up of lean and fat mass and both are involved in growth and development. Impression of these two components in bone density accrual has been controversial.Objectives:The aim of this study was to evaluate the relationship between fat and lean mass and bone density in Iranian children and adolescents.Patients and Methods:A cross-sectional study was performed on 472 subjects (235 girls, 237 boys) aged 9-18 years old in Fars Province. The participants' weight, height, waist circumference, stage of puberty, and level of physical activity were recorded. Bone Mineral Content (BMC), Bone Mineral Density (BMD), total body fat and lean mass were measured using dual-energy X-ray absorptiometry.Results:Results showed that 12.2% of boys and 12.3% of girls were overweight and 5.5% of boys and 4.7% of girls were obese. Obese individuals had greater total body BMD (0.96 ± 0.11) than normal-weight ones (0.86 ± 0.11) (P < 0.001). We found the greatest correlation between total body BMD and total body lean mass (R = 0.78. P < 0.001) and the least correlation with total body fat percentage (R = 0.03, P = 0.44). Total lean mass in more active boys was 38.1 ± 10.9 and in less active boys was 32.3 ± 11.0 (P < 0.001). The results of multiple regression analysis showed that age and total body lean mass were independent factors of BMD in growing children and adolescents.Conclusions:These findings suggest that lean mass was the most important predictor of BMD in both genders. Physical activity appears to positively impact on lean mass and needs to be considered in physical education and health-enhancing programs in Iranian school children.

Lean mass reference curves in adolescents using dual-energy x-ray absorptiometry (DXA)

“…We also observed differing body composition between sexes in adolescents above age 13 years. This pattern of lean mass quantity and sexual dimorphism during adolescence is in agreement with previous findings from ethnically diverse populations and can be explained by hormonal influences [17,[19][20][21]. A dramatic activation of growth hormone and sex steroids occur during pubertal growth spurt, which leads to rapid increases in skeletal muscle and, consequently, lean mass [22,23].…”

“…This developmental pattern agrees with the literature on pediatric body composition and could be explained not only by sexual maturation but also lifestyle influences [24]; for example, girls had greater sedentary and physical inactivity behaviors than boys, as reported in our previous publication with the sample [4]. Thus, the percentile curves hereby computed for lean mass and fat mass had a similar shape to that of previously published charts during adolescence [2,20,21]. Despite finding similar patterns of lean mass quantity during adolescence to already established norms, comparisons with previously published data indicate substantial populational variability in lean mass.…”

Muscle function and age are associated with loss of bone mineral density in Duchenne muscular dystrophy

“…Thus, those authors demonstrated more important associations between lean mass and BD than fat mass. It appears that the effect of fat mass on bone may be indirect and via lean mass, and that when lean mass is controlled there is no significant relationship between fat and BD …”

“…It appears that the effect of fat mass on bone may be indirect and via lean mass, and that when lean mass is controlled there is no significant relationship between fat and BD. 30 Proinflammatory cytokines are a marker of systemic inflammation associated with the formation of bone, participating in the regulation of osteoblast and osteoclast function. 31 We did not observe any contribution of cytokines IL-1 and IL-6 to BD loss.…”

Associations of Weight-Adjusted Body Fat and Fat Distribution with Bone Mineral Density in Chinese Children Aged 6–10 Years

“…However, the available evidence is not completely understood, and the results of published studies have been mixed. Some studies have reported a positive association between adipose tissue and childhood bone mineral density (BMD) or bone mineral content (BMC) [17][18][19][20], whereas others have reported a negative [21][22][23] or null [24,25] association.…”