LEP and obesity due to melanocortin 4 receptor deficiency: In contrast, Reinehr and colleagues (2011) evaluated apelin concentration, weight status, body fat, insulin resistance, leptin and obesity-related cardiovascular risk factors before and after one-year lifestyle intervention, demonstrating that weight loss in obese children was not associated with changes in apelin concentration as the authors have hypothesized, and no significant relationships were found between apelin, insulin resistance, cardiovascular risk factors and obesity in children [36].