Obesity is associated with heart failure. Recognition of subclinical left ventricular (LV) dysfunction may permit the initiation of therapy to prevent the development of heart failure. In this study of anthropometric, biochemical, and echocardiographic measurements in 295 healthy overweight subjects, we sought to investigate the effect of insulin resistance and severity of obesity on LV function and to establish a strategy for detection of LV dysfunction using metabolic and echocardiographic measurements. Correlates of subclinical dysfunction (defined from myocardial deformation in a matched group of 98 slim controls) were sought, and receiver operator characteristic curves for clinical and laboratory parameters were performed to identify optimal cutoffs to permit an effective diagnostic strategy. Subclinical impairment of LV function (average strain<18%) was present in 124 subjects (42%), and 52% of severely obese patients (body mass index [BMI]>35 kg/m2). Independent correlates of strain were BMI (beta=-0.25, p<0.0001), fasting insulin (beta=-0.22, p<0.001), and age (beta=-0.18, p<0.003). In patients with a BMI<35 kg/m2, subclinical impairment was uncommon in the absence of hyperinsulinemia. Using a BMI<35 kg/m2 and an insulin level<13 mIU/L to select patients for further testing allowed echocardiography to be avoided in 35% of subjects in whom the prevalence of LV dysfunction was low. In conclusion, obesity and insulin resistance are important contributors to LV dysfunction, a deleterious effect of hyperinsulinemia on LV performance is particularly seen in overweight and moderately obese subjects, and the combination of BMI, fasting insulin, and echocardiography appears optimal for efficient identification of subclinical LV dysfunction in overweight and obese subjects.