Inclusion criteria: 1) Patient has a history of RYGB weight loss surgery; 2) subject has a plasma copper level which is 80 - 155 μg/dL for women and 70 - 140 µg/dL for men, and/or ceruloplasmin activity above 62 units/L-1; 3) subject can be matched for stage of weight management and gender with a CuD subject, 4) subject is at least 18 but not more than 65 years of age; and 5) subject has signed an informed consent.