If these changes were “trivial” everybody would be doing it
There are plenty of trivial things people may never try. That doesn't change the fact that they are indeed trivial.
Overeating is an artifact of some other condition(s). Very few people stay fat or thin their entire lives. People fluctuate over the years based on where their head is at. I've done this myself.
All that said, the changes to diet and exercise really are trivial. It's just that people choose to express their mental state this way (possibly from ignorance). It's an arbitrary choice.