INS and obesity due to melanocortin 4 receptor deficiency: In patients with obesity, two main factors contribute to decreased availability of phosphorus; firstly, ‘western’ dietary patterns, including high consumption of refined cereals, potatoes, fructose, and oils, all of which negatively impact phosphorus availability; secondly, insulin resistance, one of the most common consequences of obesity, characterized by increased insulin release, which in turn stimulates the phosphorylation of many compounds and limits phosphorus availability for ATP production, exacerbating the effects of low phosphorus availability caused by diet [88].