The Influence of Weight Loss on Fibrinolytic and Metabolic Parameters in Obese Children and Adolescents

Abstract

We studied i) whether short-term weight loss alters plasminogen activator inhibitor-1 antigen (PAI-1-Ag) and tissue-type plasminogen activator antigen (tPA-Ag) in obese children, and ii) whether changes in body composition and/or abdominal adiposity are responsible for changes in PAI-1 and tPA-Ag. 20 obese boys (mean age 11.9 yr) and 40 obese girls (mean age 12 yr) were studied before and after three weeks of low-caloric diet and physical activity. Body composition was assessed by means of bioelectrical impedance, and the waist-to-hip ratio (WHR) was measured. Blood samples were determined for insulin, glucose, triglycerides, PAI-1-Ag, tPA-Ag, and the fasting insulin resistance index (FIRI) was calculated. Boys had a greater WHR, higher levels of glucose, and a slightly greater FIRI than girls. Estimates of adiposity, insulin, and triglycerides were correlated with PAI-1 and tPA-Ag. WHR was significantly correlated with fibrinolytic parameters only in girls. Insulin and tPA-Ag contributed to PAI-1 (adj. R2 = 0.36, p <0.0001), whereas percentage fat mass and triglycerides contributed to tPA-Ag (adj. R2 = 0.469, p <0.0001). The weight loss program significantly reduced adiposity, abdominal adiposity, and lowered fibrinolytic and metabolic parameters. Initial levels of PAI-1 and changes in body mass contributed to the fall in PAI-1 (adj. R2 = 0.18, p = 0.0016) and initial levels of tPA-Ag contributed significantly to changes in tPA-Ag (adj. R2 = 0.57, p <0.0001). The results suggest that changes in fibrinolytic parameters are associated with the loss in body mass but can occur independently of a concomitant reduction in fatness. Although initial PAI-1 and tPA-Ag predict the changes of these fibrinolytic parameters, the results do not exclude the possibility that the improvement in metabolic state and changes in unmeasured parameters related to physical activity and low-caloric diet could have influenced our findings.

Overweight Latino Children and Adolescents Have Marked Endothelial Dysfunction and Subclinical Vascular Inflammation in Association With Excess Body Fat and Insulin Resistance

“…Hispanic adults with impaired glucose tolerance and diabetes have increased levels of PAI-1, which are associated with BMI, fasting insulin, and proinsulin and are negatively associated with the ISI (33). This strong association between PAI-1 levels and obesity and insulin resistance has also been identified in children and adolescents (34,35). Accordingly, our data show that both PAI-1 and t-PA levels are strongly associated with BMI and truncal fat in Hispanic youth as well as with hs-CRP.…”

Objectively measured physical activity correlates with indices of insulin resistance in Danish children.

“…Several trials have demonstrated improvements in insulin sensitivity following exercise intervention programmes [33][34][35][36][37][38][39][40][41] and, moreover, that cessation of activity reverses the training-induced changes. 37 However, in one trial involving 10 weeks of exercise training in 24 obese black girls, no significant change in fasting insulin was observed but this may be explained by compensatory behaviour, since only self-reported vigorous physical activity and not overall volume of activity was increased.…”

Features of the Metabolic Syndrome Are Associated With Objectively Measured Physical Activity and Fitness in Danish Children

“…Intervention studies in children have demonstrated the utility of increased physical activity to improve metabolic regulation after 3 weeks of daily exercise and low calorie diet (38) and to reduce BP after 8 months following three additional physical education lessons per week (39). Four months of training (5 ϫ 40 min/ week) resulted in significant decreases in insulin, triglycerides, and body fat but no changes in glucose and HDL cholesterol in 79 obese children (40).…”