| This study examined the role of body size and insulin resistance in linking lifestyle factors with major and conditional coronary heart disease (CHD) risk factors using structural equation modeling. A model was specified whereby two latent factors, body size (waist circumference, body mass index, waist-to-hip ratio) and insulin resistance (insulin sensitivity index, homeostasis model assessment, fasting insulin), mediated the relationship between aerobic fitness (maximal oxygen consumption) and diet (total fat, saturated fat, dietary cholesterol, and sugar intake from a 24-hour dietary recall), and systolic blood pressure (SBP), high-density lipoprotein cholesterol (HDL-C), and triglycerides.; In 330 adolescent boys (72%) and girls, the model fit the data [chi2 (63) = 80.30, p = .07; CFI = .99; RMSEA = .03 (90% CI = .00-.05); SRMR = .04]. The prevalence of parental history of hypertension and elevated blood pressure was approximately 50%. Sixteen percent had a parental history of diabetes, 64% were overweight or at risk of overweight, and 80% were minorities.; Only aerobic fitness predicted body size, (unstandardized coefficient = -.42). Body size and aerobic fitness predicted insulin resistance (unstandardized coefficients = .43 and -.14, respectively). Body size, insulin resistance, and aerobic fitness predicted SBP (unstandardized coefficients =.57, .26, and .21, respectively). Insulin resistance and body size predicted triglycerides (unstandardized coefficients = .16 and .12, respectively). Only body size predicted HDL-C (unstandardized coefficient = -.40). All p's < .05.; The findings suggest that targeting body size by increasing aerobic fitness in adolescents may mitigate the development of insulin resistance, low HDL-C, elevated blood pressure, and elevated triglycerides, a cluster known as the metabolic syndrome and linked to the development of CHD and diabetes. Testing this model longitudinally would support causal assumptions. |
