Our eldest takes a huge packed lunch to school as they don't have the facilities to provide hot dinners - small, independent school. Even that is barely enough for him as at 14 he's over 6'1 and still growing and is very active playing basketball 3-4 times a week.
Our youngest is on school dinners at his primary school but is asking for a lunchbox cos the portion sizes are way too small for him - he eats as much as an adult male at age 8 but if you saw his skinny little body you'd think he was malnourished (he ain't, our weekly food bills are huge and it all get eaten). We're taking him on his first holiday abroad soon, via airplane, and we know the child meal won't even cause a dent so we'll have to take some extra food with us.
Both love their veg and fruit and understand the need to limit chocolate n sweets etc on a daily basis and we eat the same meals together most days (well, with their mum as they are so hungry they can't wait til i get home to eat their dinner/tea).