Adolescent obesity, bone mass, and cardiometabolic risk factors

Abstract

Objective: To compare bone mass between overweight adolescents with and without cardiometabolic risk factors (CMR). Associations of bone mass with CMR and adiposity were also determined.

Study design: Adolescents (aged 14 to 18 years) who were overweight were classified as healthy (n = 55), having one CMR (1CMR; n = 46), or having two or more CMR (≥2CMR; n = 42). CMRs were measured with standard methods and defined according to pediatric definitions of metabolic syndrome. Total body bone mass, fat mass, and fat-free soft tissue mass were measured with dual-energy X-ray absorptiometry. Visceral adipose tissue and subcutaneous abdominal adipose tissue were assessed with magnetic resonance imaging.

Results: After controlling for age, sex, race, height, and fat-free soft tissue mass, the healthy group had 5.4% and 6.3% greater bone mass than the 1CMR and ≥2CMR groups, respectively (both P values <.04). With multiple linear regression, adjusting for the same co-variates, visceral adipose tissue (β = -0.22), waist circumference (β = -0.23), homeostasis model assessment of insulin resistance (β = -0.23), and high-density lipoprotein cholesterol level (β = 0.22) were revealed to be associated with bone mass (all P values <.04). There was a trend toward a significant inverse association between bone mass and fasting glucose level (P = .056). No relations were found between bone mass and fat mass, subcutaneous abdominal adipose tissue, blood pressure, or triglyceride level.

Conclusion: Being overweight with metabolic abnormalities, particularly insulin resistance, low high-density lipoprotein cholesterol level, and visceral adiposity, may adversely influence adolescent bone mass.

Copyright © 2011 Mosby, Inc. All rights reserved.

Figures

FIGURE 1

Mean (± SE total body bone mineral content (BMC), bone area, and mineral density (aBMD) in overweight adolescents with no cardiometabolic risk factors (CMR) (Overweight adolescents + Healthy, n=55), overweight adolescents with only one CMR (Overweight + 1 CMR, n=46), and overweight adolescents with two or more CMR (Overweight + ≥2 CMR, n=42). ■Overall P-value on the basis of ANCOVA, adjusted for age, sex, race, height and fat-free soft tissue mass. bP <0.05, significantly different from Overweight + Healthy group (Least square difference adjustment for multiple comparisons.

Figure 2. Relationship between total body bone mineral content (BMC) and total and central adiposity in overweight adolescents

(A) Fat mass vs. total body BMC, (B) Visceral adipose tissue (VAT) vs. total body BMC and (C) subcutaneous abdominal adipose tissue (SAAT) vs. total body BMC. Relationship are adjusted for age, sex, race, height and far-free soft tissue mass. N = 143