Woman too thin to live in Australia

Scotsman.com - Woman too thin to live in Australia:

"A British woman was told she was too thin to live in Australia. Helen Evans, who weighs 6st 11lb and is 5ft 3ins tall, faced deportation after she failed a health check. She has now been told she can stay temporarily.."

I have heard of people being told they are too fat(what a joke that would be if it weren't so outrageous) but too thin as well? Who has made up these weight limitations and what exactly are they and are people told? What goes on here in Australia and what is the rest of this story? Can she put on weight? How long has she weighed this much? Does she have an illness? Why was she here? Can she eat? Come on, I know we cannot be responsible for every illness and personal matter of people who come here on holidays or whatever..but what exactly is the story behind this woman? If nothing else I am sure we could discover why she is so thin..that is thin. My height and I once weighed seven and a half stone and that was thin. I was also very ill!!