Anyone done it?
My hubby has.
They weigh you, measure you, do tests for eg bone density, and you get some computer-based tests for about 90 minutes. You get a mini print out afterwards of your height, wieght etc.
All relatively painless, and adds to the info they can use for medical research - all put together to anonymise it and then it will be used spot trends and associate diseases and other conditions with certain genes and lifestyle.