daughter's diet issues

My 10 year old daughter is 109 pounds at 5 ft tall. She is worried about her weight already. I am struggling with helping her learn healthy habits and excercise without feeding her fears over being overweight. I don't won't her to become so infatuated with her body that she begins to starve herself or begins a track towards that later in life. I worry about her eating habits because she eats out of boredom sometimes. She's a dancer so her weight must remain healthy, but she is not and never will be "bone thin." She didn't inherit that body type. She is muscular and curvy just like me. However, dance isn't enough to keep her thin. The last couple of years she has gained 30 pounds. I don't know if that's normal or not. I would say not. I think she needs to pull off about 10 pounds, but I don't want her self-esteem to suffer. Ugh!! This is not fun parenting.