Abstract

BACKGROUND: Early adiposity rebound (AR <5 years) has been consistently associated with increased obesity risk, but its relationship with metabolic markers is less clear; in addition, the biologic mechanisms involved in these associations have not been established. OBJECTIVE: The objective of this study was to assess the association between timing of AR and metabolic status at age 7 years, evaluating the potential role of adiposity, adipose functionality and skeletal maturation in this association. DESIGN: We estimated the age of AR from the body mass index (BMI) trajectories from 0 to 7 years in 910 children from the Growth and Obesity Chilean Cohort Study (GOCS). At 7 years, we measured waist circumference (WC) and blood glucose, insulin, triglycerides and high-density lipoprotein-cholesterol levels and constructed a metabolic risk score. We also measured percent fat mass (adiposity), plasma concentrations of leptin and adiponectin (adipose functionality) and bone age using wrist ultrasound (skeletal maturation). RESULTS: We found that 44% of the children had an AR <5 years. Earlier AR was associated with larger WC (beta: 5.10 (95% confidence interval (CI): 4.29-5.91)), higher glucose (beta: 1.02(1.00-1.03)), insulin resistance (beta Homeostatic Model Assessment: 1.06 (1.03-1.09)), triglycerides (beta: 10.37 (4.01-6.73)) and adverse metabolic score (beta: 0.30 (0.02-0.37)). Associations decreased significantly if adiposity was added to the models (i.e. beta WC: 0.85 (0.33-1.38)) and, to a lesser extent, when adipokines (i.e. beta WC: 0.73 (0.14-1.32)) and skeletal maturation (i.e. beta WC: 0.65 (0.10-1.20)) were added. CONCLUSION: In GOCS children, AR at a younger age predicts higher metabolic risk at 7 years; these associations are mostly explained by increased adiposity, but adipose dysfunction and accelerated skeletal maturation also have a role.