I'd forgotten about the disparity between male and female deaths as well, thank you to PP who mentioned that one.
As for Public Health England, they've always been one of the better paid bits of the NHS "family" despite many of them not having set food inside a real hospital or frontline service for a VERY long time. Still, policy costs, I suppose.
And no, it isn't only up to Public Health England. It's also up to companies like Coca Cola (or whatever they're called this week), Mondelez, McDonalds and the rest having more responsible advertising, and to fresh food being made more available and more cost-effective even in cities (though the way things are not sure if that will be happening any time soon). More allotments and community gardens.
Much of the current education system is absurd too. Teach kids things they are going to need to know in schools - how to grow things, how to mend things, how to get on with other people. Home economics, how to use leftovers, how to preserve food. How to stay fit when you hate team sports and the games teacher is a monster. (Sorry, non-monster games teachers, but there were an awful lot of sadists who'd gone into PE teaching around in the 1980s.)
Not sure how useful the Michael Gove "let's all read British literature by long-dead Victorian poets" approach from the most recent revision is going to be in the next 50 years. Not that there's anything wrong with British literature, but if it comes to deciding what should have a bit more time on the syllabus, growing things or reading Thomas Hardy, surely no one with any foresight would opt for the latter over the former?
Or of course we could just go the whole hog right now and move across to a synthetic/processed Blue Sun or Soylent Green type bar (not made from people, obviously) with all the nutrients you ever need, carefully measured out so no one ever goes over their decreed allowance....