They can do as you stretch the skin or shrink the skin, weight loss afaik is less harmful though SEVERE weight loss can be bad for them, Most will survive getting stretched a little so long as you rub cocoa butter on them religously and get a touch up done as soon as possible (advice given to pregnant women with tatts) I tend to know a little more about these things since I used to be with Twisted Tinkerbell when she got her tatts done and well when waiting on her comming outta the studio I used to talk to the tattoists about stuff generally to do with their work. I also used to read all the information they gave for looking after stuff.

My advice (comming from tattoists themselves) is to have a theme, be it fantasy, tribal, celtic, oriental and stick to it. Don't get a tribal arm and a celtic chest piece it looks messy I was interested in going with 2 quite large fantasy styled pieces one being the phoenix rising from the flames on my arm curling around the shoulder (though I doubt I have the meat/muscle for such a stunning piece) and 2 dragons carved of stone facing each other before the moon each with a different eye colour one to represent the good in me one to represent the bad in me.