PTH and obesity due to melanocortin 4 receptor deficiency: Therefore, an excessive dietary intake of phosphate induces the secretion of PTH and FGF23.(17,18) Several studies have suggested that elevated PTH levels may be a risk factor for metabolic syndrome.(19,20) In adipocytes, PTH induced insulin resistance and fatty acid release.(21) FGF23 also affected obesity in people with normal kidney function.(22)