Dietary content and combined training, but not daily physical activity, are associated with 6-month bone mineral changes in adolescents with obesity: a secondary analysis of the PAC-MAnO trial

Abstract

Purpose: The present study aimed to explore the influence of diet and physical activity (PA) changes on bone mineral content (BMC) and density (BMD) alterations in adolescents with obesity undergoing a weight loss program.

Methods: Six-month longitudinal data from 71 adolescents (aged 15.1 [± 1.6] years; 57.7% girls) with a BMI z-score of 3.03 (± 0.78), previously recruited for the PAC-MAnO trial, were analyzed using Generalized Estimation Equations for over time changes and linear regressions with BMC, BMD and BMD z-score as dependent variables, adjusting for confounders (including type of exercise- aerobic vs. combined).

Results: Adjusting for confounders, changes in carbohydrate (CH) and protein content showed to positively and negatively predict BMD z-score variance, respectively (β = 0.44, 95%CI: 0.01, 0.04, p < .001); β = -0.57, 95%CI: -0.06, -0.03, p < .001), yet no associations were found between PA and bone-related parameters. Combined exercise showed better results on BMC compared to aerobic exercise (β = 0.09, 95%CI: 0.05 to 0.13, p < .001).

Conclusions: Increased CH content, instead of protein, may be associated with BMD improvements in adolescents with obesity. Type of exercise may moderate the impact of PA on bone health.

Trial registration: Clinicaltrials.gov NCT02941770. What is Known • Adolescents with obesity may be at a higher risk of osteopenia/osteoporosis • Obesity and inadequate diet and physical activity (PA) may have an adverse effect on bone metabolism What is New • Improvements in adiposity and muscle mass and increased diet carbohydrate content are associated with bone mineral density (BMD) improvements • Type of exercise (i.e., combined training vs. aerobic) may moderate the impact of PA on BMD, and calcium intake may mediate this impact.