Waist circumference is a very important factor in deciding if someone has the potential for obesity, but there has been no device that automatically measures waist circumference. In this study, a new waist circumference measurable belt was devised and is accurate to 5mm resolution. The system is comprised of magnets and magneto-resistive sensors to measure waist circumference. A novel algorithm was developed to distinguish the belt moving direction. This belt system can assist in obesity and overweight management and a connection with IT and communication networks may make this system a more powerful tool.