Nothing, you probably just lived in your bubble. Kids have a very narrow view of what reality is

Poverty has been linked to obesity for a while now, feel free to google it. It's a form of malnutrition, not a form of food abundance, poverty doesn't mean you can't buy food, it means you probably are more prone to looking for a quick feel good food because the rest of your existence isn't very fulfilling, it means you probably don't have a fully equipped kitchen, it means you can't afford fresh food, it means you're more likely to buy processed food of dubious nutritional value, &c.

> £4bn that has to be found year on year.

That's not even 10% of your military budget. Building a strong and healthy population should be high on the list of priorities, the saving in term of public health would more than pay for it