Circulating klotho levels were negatively associated with being overweight (beta coefficient: − 22.609, p = 0.0025), obesity (beta coefficient: − 23.716, p = 0.0011), current smoking (beta coefficient: − 46.412, p < 0.0001), and alcohol consumption (beta coefficient: − 51.194, p < 0.0001). Here, KL is linked to obesity due to melanocortin 4 receptor deficiency.