I think it's an over simplification to say it's just down to poverty and that expressing concerns over childhood obesity is just another form of poor people bashing. A friend of my husband is permanentl skint and his wife hasn't done paid work in years, but she's Italian and so proper home cooked food is part of their culture. So the kids get proper home cooked meals all the time, and are healthy.
Our ready meal culture is definitely part of it. I also think we need to change the way PE is taught in school. My experience of PE at school was, due to resources at school, mostly focussed around team games/ball games (hockey, netball, rugby, football etc). If like me, you were uncoordinated and couldn't throw or catch, and you couldn't run fast, PE was something to be feared, where you would be exposed by o scorn and ridicule by your contemporaries.
So after school I did very little exercise for years. Luckily I'm naturally slightly built anyway and with a metabolism that baffles most of those around me, so I got away with it for a long time.
I've since found loads of types of exercise that suit me that weren't options at school. Rowing at Uni (sadly only available at posh schools....mine was not posh) being one example. It's something that anyone able bodied can do, the basic technique is very easy, and once you've cracked that, it's just a case of improving your stamina and fitness and strength and then your speeds will improve. Middle distance running - anyone can train to do a 10k, and my times have never been that great, but I can manage them and there is a sense of achievement there.
There's probably thousands of kids who had similar experiences too me at school and spent years fearing being laughed at if they stepped anywhere near sports field. Many of them will be less lucky than me though and not be able to stay as slim as I did in my lazy years. What we need, imo, is the resources to allow schools to find a sport that suits each child, and give them opportunities to participate and enjoy that sport. That way they will be motivated and do it for fun. Get them into good habits for sustainable active lifestyles.