FGF21 and obesity due to melanocortin 4 receptor deficiency: A recent study demonstrated that the combined whole‐body deletion of FGF21 and GDF15 does not exacerbate DIO, but results in significant worsening of hepatic steatosis and insulin resistance relative to that observed in GDF15 single knockout mice, indicating that these endocrine factors might act synergistically to protect against obesity‐induced metabolic derangements [25].