I have never tried any of the "fashionable" diets - I firmly believe that losing weight involves spending more calories than you eat, nothing more than that, so eat less and exercise more! For that reason I totally agree with your "trite" advice Marc!!
I do have some health issues which limit how much I can do the "exercise" bit so for me it's mostly "eat less". Not making excuses though, I can still exercise.
I reckon in my case the issue is snacks, between meals which I've cut out completely as of last weekend, and booze. I will often sit on my own at the computer of an evening and have a whisky or beer which can easily become 3 whiskies or beers, not healthy. Maybe should try limiting the booze to social occasions only?
I've used an app called Lifesum which is basically a way of easily counting calories. You set your target weight and you can choose how quickly you want to get there.
Then you enter the food you're eating - it can scan barcodes which helps a lot! - and it tallies up your daily allowance. I don't eat breakfast anyway so I've basically got my daily calories over two meals, which sometimes I actually struggle to get to. I rarely feel hungry.
Lifesum seems pretty good re privacy. You can opt out of data collection and marketing.