Well funnily enough I had a healthscare last year and have since lost 2.5 stone. We were eating a lot of convenience food: Finest Lasagne, ribs, steaks, pasta with rich sauces, lots of cheese, bought puddings, cream, butter, ham, bacon, red meat generally, refined carbs.
I no longer use white pasta, white rice, refined sugar, cream, very limited cheese, no butter, nothing processed. No alcohol.
Lots more chicken, fish, turkey, beans, veg, fruit, etc.
Funnily enough my food bill has reduced by about 30%. My cholesterol is down to 5.4 from 7.8, my fatty liver is reversed, no more hunger spikes, no more eczema or ache's and pains.
It took giving up yummy, quick food. It isn't about cost at all but mindset.
Something I remember from childhood is the boring dryness of food. Mash, cold meat, chops and veg. It doesn't have to be that way, however, do most people look forward to basic food or fast, yummy food.
Change has to happen at an individual level. People have to learn to budget properly.
Advertising only works if people have money to spend.