TLDR; Lost 30+ lbs over 10 yrs, but no significant oscillating. Weight has stayed off.
I feel like any "diet" is doomed to fail long term. I've been 180-ish for at least a few years now, down from 215 at peak. I've since been through a couple of laptops so don't have early data anymore, but I'm thinking I started the descent around 2009. Two major factors early on were gall bladder removal and 98% stopping alcohol consumption which had primarily been beer. The first few years were like 5-10 lbs lost per year as my stomach adapted to eating smaller quantities to avoid aggravating effects of gall bladder removal. Over time this has led to eating less more often during the day as a life habit. After the first few years I had losses more in the 1 - 3 lb range per year. For about ten yrs straight I never had a weight gain as a yearly average until I bottomed out around 179 lbs. Now I oscillate between 179- 182. I could ideally lose a few more but I've been happy with where I'm at now. Adding in some strength training helped as dropped below 190. I don't do any kind of calorie tracking, but until recently tracked my weight daily with concern for monthly and yearly average (helped to stay disciplined during cravings). I focused on trying to understand real hunger vs bored hunger and only eating when truly hungry. I try to focus on not eating until I'm gorged. As a rule I don't eat a lot of junk between meals, but I do splurge on occasion; weaknesses for ice cream and pie.
I've been a consistent recreational cyclist since early childhood.