There used to be a TV show called "Honey, We're Killing the Kids!'
It was another classic in the genre of making fat people take a long hard look at themselves whilst, at home, other people take a long hard look and feel smugly superior. Which is always nice.
The programme would take a family of above average build with a child, let's call him Andrew. The child is already a bit of a chubster. The programme makers then proceed to analyse the child's diet, its psychological profile and its habit of buying sweets with money it 'found' in the house. And getting mixed up in Halloween high jinks...
The programme then made the parents feel guilty and made them feel like all this was their fault. In the example I'm using I should say that it wasn't!
Then using some CGI wizardry generated on an Atari ST, the programme makers dramatically aged the child through the next 40 years of abysmal food and lifestyle choices until they stop at a hideous, deformed creature something like this...
The parents reel back, not realising that this is not the truth. They cry. They clutch each other in horror. "How could we do this to little, Andrew? What kind of monsters are we?"
But it turns out that this need not be the future. The programme makers can roll back time like a boring version of Doctor Who. They tell the parents that you can rewrite history, it is not fixed!
And they tell the parents and the child how to do it. And then, having done this, they age the child again and, it is true, the future has changed. This is what Andrew grows up to be in this happier alternative future.
And then they all go home and eat cake.