I'm not saying we should except obese DCs, but yes I think we do have to accept the reality is that they are bigger than we were.
They are also taller and have bigger feet. That's probably also true of most of us if we look at our parents.
I'm actually slightly shorter than DM, but my DSIS, DSIL and most of my friends weren't. DD1 is taller than me and her DFs are either taller than their mums already or will be by 17.
So I don't think everything about modern living can be 100% bad and unhealthy.
The one think that could be improved, relatively easily, is after school activities for Y6-Y9 (10-14 girls).
If you are not 'sporty' the amount of recreational sport very small.
DD1 would have done, aquarobics, water polo, or some other fun swimming, but there is nothing, if you don't race.
She trampoline a bit, but the coach left and she felt too tall to do gym with tiny Y4s. School sets for sport and they do fun aerobics and dance and swimming for the non competitive ones, but it's not enough.
They need lunch time clubs and after school groups that do "active, but non competitive things.'