Fat mass accumulation compromises bone adaptation to load in finnish women: A cross-sectional study spanning three generations

Abstract

Body weight and lean mass correlate with bone mass, but the relationship between fat mass and bone remains elusive. The study population consisted of 396 girls and 138 premenopausal mothers and 114 postmenopausal grandmothers of these girls. Body composition and tibial length were assessed using dual-energy X-ray absorptiometry (DXA), and bone traits were determined at the tibia using peripheral quantitative computed tomography (pQCT) in the girls at the ages of 11.2 AE 0.8, 13.2 AE 0.9, and 18.3 AE 1.0 years and in the mothers (44.7 AE 4.1 years) and grandmothers (70.7 AE 6.3 years). The values of relative bone strength index (RBSI), an index reflecting the ratio of bone strength to the load applied on the tibia, were correlated among family members (all p < .05). The mean values of RBSI were similar among 11-and 18-year-old girls and premenopausal women but significantly lower in 13-year-old girls and postmenopausal women. However, in each age group, subjects in the highest BMI tertiles had the lowest RBSI values (all p < .01). RBSI was inversely associated with body weight (all p < .01), indicating a deficit in bone strength relative to the applied load from greater body weight. RBSI was inversely associated with fat mass (all p < .001) across age groups and generations but remained relatively constant with increasing lean mass in girls and premenopausal women (all p > .05), indicating that the bone-strength deficit was attributable to increased fat mass, not lean mass. Moreover, the adverse effect of fat mass was age-dependent, with every unit increase in fat mass associated with a greater decrease in RBSI in pre-and postmenopausal women than in girls (all p < .001). This is largely due to the different capacity of young and adult bones to increase diaphyseal width by periosteal apposition in response to increased load. In summary, increasing body weight with fat accumulation is accompanied by an age-dependent relative bone-strength deficit in women because the beneficial effects of increased fat mass on bone, if any, do not compensate for the mechanical burden that it imposes. ß

Body fat in children does not adversely influence bone development: a 7‐year longitudinal study (EarlyBird 18)

“…In all, contemporary children are more adipose, but this does not appear to disadvantage their bone development, and there was no evidence in these adolescents for the lower aBMD related to high BF reported in adults (7,29). BF has no effect on the age-dependent rise of aBMD in boys, but a positive and systematic effect in girls.…”

Heterogeneity in resistance training-induced muscle strength and mass responses in men and women of different ages

“…The lean mass of the lower limbs were assessed according to software-generated regions with manual adjustments. In a previous study from our laboratory, the CV of two repeated DXA measurements was 1.0 % for lean tissue mass (Xu et al 2010). In study cluster 3, different methodologies were used concurrently within the experiments.…”

Lactation is associated with greater maternal bone size and bone strength later in life

“…Of the eligible subjects, 396 girls participated in the laboratory tests one to eight times during a maximum period of 8 years. In the years 2003-2004 and 2007-2008, we invited the girls' other family members to participate in the Calex family study [20,21]. Only the mothers from the later recruitment period are included in this present report.…”