The obesity of patients with Laron Syndrome is not associated with excessive nutritional intake

Objective: To study the metabolic parameters which may affect the excessive weight of treated and untreated patients with Laron Syndrome. Design: Body composition, daily caloric intake and resting energy expenditure (REE), when possible, were measured for each patient. Caloric intake was calculated based on 7-day food records, REE was measured by indirect calorimetry and body composition was determined by dual energy X-ray absorptiometry (DEXA). Subjects: Nine untreated adult subjects with Laron Syndrome (6 female subjects, 3 male subjects) aged 28-53 years and 4 girls with Laron Syndrome treated by insulin-like growth factor-I (IGF-I) 120-150 μg/kg/d were included in the study. Results: Patients with Laron Syndrome have an abnormally high body fat (BF) mass (54 ± 10% of body weight) and a relatively low lean body mass (LBM) compared to a healthy normal population. Energy intake varied but in most of the patients was not significantly higher than the measured REE. The REE corrected for LBM was higher than expected, based on our norms for healthy adults. The mean distribution of energy sources in the food was 47% carbohydrates, 17% protein and 36% fat. Conclusion: The severe obesity of patients with Laron Syndrome is not due to hyperphagia or hypometabolism.