Disease of the veins include blood clots, varicose veins, leg swelling, and sores on the legs. Venous disease is more common in overweight patients, but little is known as to why this is the case. This research project is investigating the relationship between body weight and function of the leg veins using a special non-invasive technique known as venous plethysmography. We hope to investigate the reason for the relationship between body weight and higher risk of vein problems.