A recent study assessing IGF-1 implication in the development of obesity [166] using mice with myeloid cell-specific ablation of IGF-1R and challenged with a high-fat diet showed increased macrophage infiltration in adipose tissue leading to insulin resistance and also suggested an anti-inflammatory role for IGF-1 on macrophages. This evidence concerns the gene IGF1 and obesity due to melanocortin 4 receptor deficiency.