It'd be surprising if that applies in this context. In the case of the individuals OP mentions, their parents would not have been exposed to ultra processed food (or barely, perhaps only after they've reproduced), so ehatever gens they passed on would not have been adapted. There's simply not enough generations in this case. Especially not for such significant changes.

In any case, it's moot as by and large the westeren diet is not good for the population, exceptions are simply that.