in general it is best to keep the focus on healthy eating and activity. it sounds like you are already doing a great job of emphasizing healthy habits. physical fitness basically how well your child's body works as she plays and learns (for exampler her energy level endurance strength) and not size is key. combatting the media's and society's biases about physical appearance is not easy. offering counter-examples of healthy (and realistic) body types might be something to try if she is a fairly mature 5-yr-old. also maybe showing the graph of bmis on the growth chart to your daughter might allow you to show her that she is tracking along just fine and that she is in the healthy range. i think this sounds like something that should be explored in depth with your pediatrician or a counselor. here's a few body image related articles for parents who might be facing this situation with older children. eating and body image: a troubled relationship moms kids and body image
my daughter is 5 years old and obsessed with her weight. is she developing an unhealthy body image?