Stop dieting.
I got to mid 50s before gaining weight kicked in and had a whale of a time trying every diet known to man kind.
What works (for me) is to eat everything I always ate, and enjoy, but in smaller quantities.
I halved everything (roughly), but added proteins to fill me up
.Still had weetabix / Porridge, but would have half my usual amount and add in fruit. And yes, I know fruit has sugars. Don't care, its natural, not processed.
I had half the amount of soup for lunch, with a slice of toast, or a sandwich, fit to bursting, with one slice of sourdough.
Dinner as usual. Fish and chips? Oh yes, just less of them. I promised myself if I was hungry, I could always have more, but I was never hungry...just greedy!
I eat normally now. I realised I was just eating too much before, but have not denied myself anything, so its more of a change of eating, rather than a diet.
No problem with it at all
Oh, and I eat chocolate, crisps and takeaways. I'm just more aware of what I'm eating and make adjustments.