I was told by my doctor that I had let my weight creep up through lockdown. I bought a Fitbit and I use the app to record everything I eat and drink and it allows you to see how many calories you are burning so how much you can eat. In about three months I have lost 8kgs without increasing my exercise (mostly walking, though want to start swimming again soon) I have reduced bread and processed meat consumption. I have done this before and it works for me, by losing weight slowly when I reach my target weight I can maintain it pretty easily by monitoring my weight weekly and if it starts to creep back up a couple of weeks back on it will drop the odd pound and eventually you will re-educate yourself to how much you can/should eat.
Best tip I can give is drink at least half a pint of water (preferably a pint) before every meal, it will make you feel fuller when eating and keep you hydrated.
Yeah, recording and understanding is the key.
The reason slimming world and the likes don't use calories and macros is that they don't want people to understand, they want people to keep coming back, the system is designed for people to make small gains, fail and then come back again.
They push their "meals", when other cheaper replacements are more nutritious and fewer calories, and allocate less "points" to their meals than the alternatives, it's bizarre, and like a cult.
The reason they don't push exercise is they don't want people to gain muscle/ fitness and become naturally leaner.
Also, remember that processed food can be +/- 10% accuracy and steps/ heart rate are not a true reflection of calorie burn/ efficiency. They're both a very good guide, and much better than being ignorant of it, but for some people, they could need to tweak things. Doing similar things for a while will ultimately train people to understand their body v life.
There's also that all calories are not equal, a balanced and varied diet is good, and still have treats, but try and stick to decent macros.
Good tip on the water, it's like having soup for a starter, those who have soup consume fewer calories for the whole meal and are less likely to get a desert too.
I have fibre supplements too, on some occasions, they help.