I feel like I'm failing at Parenting 101 when it comes to meals. All ideas welcome!
I have an overweight 8 year old daughter. She is tall for her age at 136cm but is also visibly fat around her torso and stomach. Her legs and arms seem in proportion to her height.
DD eats at her childminders three nights per week, where the food offering is typical "kids meals" of macaroni cheese / pizza and chips / sausage casserole etc. I am reluctant to ask the childminder to police portions as I don't want her to feel singled out on a table full of kids. I also don't think she eats excessively there (they have a small healthy snack when they get home and then tea before pick up).
At home, I am losing the plot with what to cook. DD will eat anything, but her fussy brother basically only eats meat. I think I've spent so much energy trying to create meals he will eat that I have lost the desire to cook anything at all. Which means we fall back on spaghetti bolognese (brown spaghetti), ham and cheese omelette, beans on toast, pasta with ham and cheese, sausage and mash etc. DD is always hungry and would like enormous portions, though I do try to limit it to what I see as a reasonable portion. She will also steal food and eat in secret, particularly if she is cross with something. I am getting better at preventing the stealing, but she'll literally take anything; a biscuit would be her go-to, but she'll take a plain slice of bread if that's all she can find 
At home we eat by serving ourselves from serving bowls to encourage fussy brother and my youngest to try different foods and regulate their own appetites. We've always done this, but I am aware it may mean DD is serving more than she should have.
DD is active. She had a gymnastics class, a street dance class and junior park run every week, and walks home from school (a mile) three times per week. She also swims one week and cycles 5 Miles+ the next, alternating the activity each week. We have a large garden and now it's sunny she spends hours out there swinging/trampolining/cycling/chasing her brothers etc etc.
After all that context, I think I need healthy meal ideas that are filling but low calorie but also suitable for a 4 year old. At this point fussy brother will just have to go with whatever he gets as he doesn't eat anything but meat anyway. If there's anything else I could/should be doing then I'm happy to take any advice!