For research volunteers that are happy to undergo a small fat biopsy, a sample of abdominal fat will be obtained by firstly injecting some local anaesthetic into an accessible area of the abdomen. Using a scalpel, a small incision (approx 2-3 cm) will be made to a depth of approx 15mm and two small pea-sized samples of fat will be removed. The wound will be closed with simple sutures or steristrips. One fat sample will be flash frozen in liquid nitrogen immediately after excision and stored at minus 80 degrees for RNA analyses. The other sample will be stored in formalin for later immunohistochemistry staining.