Well, I was lucky in that my slender child came first, so that's my 'norm'. Right now, my kids are 9 and 6. My 9 year old weighs 74 lbs. My 6 year old weighs 68. It freaks me out occasionally that my 6 year old weighs only 6 lbs less than my 9 year old. Dd is in the 95th percentile for height, and the 88th for height. That's been her curve since she was a baby. Ds, on the other hand, is in the 96th for height and the 64th for weight This too, has been his curve since he was a baby. He was sick last week and lost a couple of pounds (so, he may actually weigh LESS than 74 lbs. right now). i swear the only thing that's keeping his pants up is his 4 T a day Nutella habit. He feels incredibly fragile when I hug him. And yet, he's not. He's full of energy, doing well at school, and generally fine.
Â
I think that you just have to trust that this is her curve. I suspect, if you look at your slender child and your more sturdy child, you'll also find differences in how much they move. One of the reasons our ds is thinner than his sister is because he simply is more active. He moves all the time. When he's bored, he'll go shoot the nerf basketball into the hoop on the back door. He used to run laps around our house in the evening. One day when he was 3 or 4, he ran laps for 30 minutes, just to see if he could! Dd, on the other hand, is much more likely to sit down and sort her beads or give names to all her coins (her activity last night). She's intellectually very active, physically not so much so. She hates to get hot. She declared last year that she's not going to do any sports where you have to run and get hot. Um... OK, I think we'll sign you up for the swim team!
Â
You might try, for both of your children, smaller meals, but more frequent ones. That might help your younger child eat more, and your older child to not get so hungry so she doesn't overeat. It takes awhile for my older daughter to feel full, and so eating small bits more frequently actually helps.