I've lost 76lbs since some of my tattoos. They all look brand new. If you are worried about that, you could always get them put in places with less fat. Ankles, wrist, etc.
They can if you get tatted in a place where muscle definition changes. But for the most part you should be okay. Just pick your placement in an area that doesn't change much as mentioned above.
Thanks! Your answer is awaiting moderation.