INS and obesity due to melanocortin 4 receptor deficiency: An interventional study indicated that weight loss (−1.8 kg/m2 of BMI in a diet intervention group and −3.3 kg/m2 of BMI in a diet-and-exercise intervention group) improved insulin sensitivity in Japanese patients with obesity and type 2 diabetes.29 Improved insulin sensitivity was also observed in Americans who maintained their weight with treadmill-based exercise and no alteration in their diet.30 Studies have also demonstrated that building muscle through exercising without changing weight improves insulin sensitivity.31