Obesity dynamics and cardiovascular risk factor stability in obese adolescents

Aim: Cross-sectional Studies showed worsening of cardiovascular risk factors with increasing severity of childhood obesity. The aim of this Study was to investigate the impact of obesity dynamics on cardiovascular risk factors and on the stability of the diagnosis of metabolic syndrome (MS) in obese youth. Methods and results: A longitudinal assessment of components of the MS using two definitions was performed in 186 obese adolescents (106 females/80 males, age 13.1 +/- 2.5 yr). Components of the MS were assessed at baseline and after 19 7 months. We stratified the cohort into three categories based on the 25th and 75th percentile of body mass index (BMI) z-score change: category 1 reduced BMI z-score by 0.09 or more, category 2 had a BMI z-score change of between -0.09 and 0.12, and category 3 increased BMI z-score by >0.12. Subjects who reduced their BMI z-score significantly decreased their fasting and 2-h glucose levels and triglyceride levels and increased their high density lipoprotein cholesterol in comparison to subjects who increased their BMI z-score. BMI z-score changes negatively correlated with changes in insulin sensitivity (r = -0.36 p < 0.001). Among those with no MS at baseline (n = 119), 10 (8%), most of whom significantly increased their BMI z-score, developed MS. Of 67 who had MS at baseline, 33 (50%), most of whom decreased their BMI z-score, lost the diagnosis. Conclusions: Obesity dynamics, tightly linked to changes in insulin sensitivity, have an impact on each individual component of the MS and on the stability of the diagnosis of MS in obese youth.