I don't think the body fat calculator works either, it made be obese when at 5ft and 7 1/2 stone most people tell me I'm under weight. I personally don't think you can take these test too seriously.
I've been reading a few of other peoples post and in a way its nice to see that there are other people who are trying to gain weight

Since I was about 12 I've been struggling to keep weight on, at the moment I'm quite happy with my current weight, but my weight fluctuates between just under 7 stone to just under 8 stone. I've found that when I'm stressed or have joint pain I eat less and when I'm happier and pain free I eat more.
I was reading mami2fours post and I don't see that if your kids eat lots of junk food it will help, I eat a lot of junk food and I'm still skinny. From personal experience, I've found that eating one proper meal a day sat down with my family, has helped me maintain my weight, its when I'm on my own and don't feel so well that I just don't bother to eat. I think people putting presure on your kids to eat will just cause problems, as long as they are happy I don't think you should put pressure on them to eat more.
I went through a stage when I was in my early teens and things were a little difficult at home, I would have to leave at least one thing on my plate at the end of a meal. I know this is a form of eating disorder, and it wasn't helped my anxiety attacks that started when I was doing my GCSE's, but I've managed to over come these problems and although I still don't eat healthily, I eat a lot better than I did.
And if anyone know of a good gluten free muffin recipe could they let me have it.