FGF21 and obesity due to melanocortin 4 receptor deficiency: In normal weight (BMI = 18.5–24.9 kg/m2) men and women, FGF21 was found to be acutely increased in plasma after exercise; however, since our sedentary group had an average BMI classified as overweight (25–29.9 kg/m2), perhaps the response in FGF21 secretion was altered similarly as in patients with obesity.