an increase of fat people dying because fat adults these days aren't people who got fat as adults. More and more of them have been fat since childhood

This. The damage is cumulative. The cases of T2 diabetes among teenagers went from ''unicorn'' to ''common''.

The fat degenerates successfully shifted the social norm so that it is now acceptable to make your child fat even at the age you are 100% in control of their diet.

Personal responsability for one's weight gradually comes during teenage years when someone makes decision about what and how much they eat, + they are expected to have the mental development to understand the excess energy they consume is stored as fat.