DD1 doing quite a lot of sport-what can I feed her so she doesn't fade away?

[Mirage]

DD1 is 8 and does PE twice a week,swimming once,cross country once all at school.Then she rides her pony and her bike about 3 miles a day 6 days a week and goes to a running club for 1.5 hours on a Saturday too.She is such a slight little thing that I'm worried that she'll disappear [she always has been whippet like].What can I feed her to keep her energy up and stop her fading away to nothing?
Thanks very much.

Off the top of my head I'd say complex carbohydrates, stuff like porridge for breakfast, potatoes, brown rice. Give her good size portions and regular snacks. I wouldn't worry as long as she's maintaining her weight and isn't fatigued.

Thankyou,I'll persist in trying to get her to like porridge.She has decided that she likes bananas now,which helps.

if her diet is too high fibre she may struggle to eat enough but she should sort of naturally eat enough to fuel herself