I am in my second year of controlling my weight. Down ~30kg and I am in the healthy range now for more than 6 months. So far it seems to be sustainable. I am in a paid fitness (online) group and I have learned a lot, though it's still up to me to find ways to fit into the requirements... Here are some random observations that seem to work for ME (might be different for you).

- Nothing "extreme" works for me, as it's not sustainable for periods longer than a few months. I did keto... works for some time, then a total rebound. In the end it seems that a "balanced diet" works. For me (and my training regimen) this means 150g protein, 180g carbs and 50g fat per day.

- While you are cutting, you have to weigh everything you eat. There is no good way around this as you cannot control what you don't know and you can't know how much you eat unless you measure it.

- It's perfectly fine to eat completely uniform food every day for some months. For the first months, for me it was chicken breast, raw cabbage, peaches, cheese and the occasional high-protein pudding. This puts the dopamine under control, as you (or at least me) get trained to not expect anything "special", ever. After some months I was able to start varying a bit, while still staying 100% within my macros (no more and no less of each macronutrient). After some time I stopped weighing the veggies I eat and now I eat all of them (like broccoli, kale, turnips, tomatoes, cucumbers, salads etc.). I eat all kinds of meat and seafood. Mostly never eat any vegetable oil, as meat and cheese provides the needed quantities.

- Yeah, what I described above is almost exactly the same as your described "quitting food", just it's "healthy", as you consume enough fibre. Yeah, do supplement with some multivitamins.

- You have to cook, no way around it. But it's not as frightening as it sounds. Once you accept bland (and uniform) food... it's easy. Buy an Instant Pot and start prepping the meat there. 2 kilos of chicken breast under pressure for 10 minutes will last you a week.

- Always have your "correct" food handy, so that you don't need to eat something else, or think what to eat. (yeah, buy the instant pot).

- Throw away all the "junk" food you own and never buy any.

- If you are out and you are not able to eat your "right" food, just fast and eat at home whenever that is. Yeah, I get it it might not be possible for everyone, but it's possible for me.

- Don't do this initially (the first months), but later... everything is allowed if you do not exceed your macros. French fries? Alright, you can have that now and then. Pizza? Sure thing, I am having a slice or two almost every week. But never exceed macros.

- Artificial sweeteners are your friend when you are in a crisis. (Ab)use them as much as you want and you are still better than being fat (or having bad lab readings as you mentioned).

- If you are still hungry, always have cabbage/kale/etc. handy. You can eat as much as you want in raw form (and in several months you will start to like it, I promise).

- Fasting is mostly not a great idea as it doesn't help you learn how/what to eat and how to control your cravings. After lots of experimentation with it, I arrived at 3 meals a day with carbs early in the day. Breakfast in the morning, then lunch, then a light dinner around 4 and no food afterwards. Yeah, if you are a social person it will suck. But I guess you can find your own thing... but don't be afraid to experiment and don't have prejudices. I always thought that having breakfast is not my thing (or a good idea) despite the overwhelming evidence for the contrary. Yeah, there are actually studies that show that it's beneficiary to eat early in the day, opposed to late. But if your body is broken you will need time to arrive to this.

- Despite the previous point, initially do whatever works. At least for several months. Then what works will change. Do not be afraid to follow along.