I think metabolic changes and hyper-palatable foods better-explain obesity compared to faulty satiety/fullness signals. Slow metabolisms due to age or genes combined with hyper-palatable foods, such as carbs and fats combined, are a recipe for obesity.
That being said, if you were legitimately muscular in your 20s and lost most of your muscle as you got older/married/had kids, that can reduce your caloric needs and make it seem like your baseline metabolism is changing more than it is.
I jumped on intermittent fasting very early on because it worked, but after doing it off and on for a few years (on: getting smaller, off: getting fatter), I simply started finding it easier to control portions or to wait a little longer for my next meal. I blame it entirely on learning to live with hunger on fast days.