Yes to it being a constant effort.
I'm sedentary which means eating less than most people would like and very little junk food.
A typical week would see me skip breakfast half the time and eating lunches and dinners like jacket potato and beans, the fabled mumsnet massive salad, bread and butter, overnight oats, curry without rice or naan, soup, stir fry, noodle bowls, tapas.
I do have a milky coffee and chocolate every day, but like pp, usually just a bag of buttons. Takeaways only a couple of times a year.
I don't eat meat or dairy and I eat minimal upf. I also eat high quality stuff which I think helps a lot e.g. a posh olive bread roll with butter, not a torn up bap from a cellophane packet, so the actual nutrient density and flavour helps me feel satisfied .ore than the volume iyswim.
I have now started going to the gym to maintain muscle mass as I'm just hitting 40 and need to keep on top of that.
It's not easy, no, and it annoys me when people say I'm lucky to be slim. I'm not lucky- it's constant effort! I used to be big 20 years ago so it raises my hackles a bit because I feel like it undermines the effort. That said, it's worth it to me because it's not just about fitting into jeans, I want healthy knees and lungs for hiking when I retire and so I'm now more focused on doing the work that will help me in 20 years time. I wish 20 year old me had done the same!