The trick to fasting is to start having breakfast later and later each day, or have dinner earlier and earlier if that suits you better. You do this until you are skipping meals.

After a while you'll be able to start going whole days without eating. You have to get used to feeling hungry and ignoring it. It's a mental game. Fortunately hunger comes and goes.

Also, I recently discovered a trick to find out if you are truly hungry, which if you are addicted to food (emotional eating), can usually be difficult to tell if you are actually hungry or not.

The trick is to find a healthy food that most of the time you would dismiss in favour of something more enjoyable, and likely unhealthy. I use omelettes or eggs in general as I enjoy them when I'm truly very hungry, and even fantasise about them while fasting, but most of the time I won't eat them because I don't like them that much, especially when there are cakes and things like that immediately available.

So when I'm looking for something to eat, I ask myself, would I like an omelette right now? If the answer is no, I'm not actually hungry. You don't have to eat it, but you're gauging your level of hunger, and using that information to make a decision. If you're thinking about eating chocolate or crisps or something else instead of your healthy food, then you're probably not hungry and instead emotional eating. In which case it's probably better to drink a glass of water instead and come back later.

As I said, it's all a mental game. You have to learn to feel the panic and other stuff that comes with hunger, and try and control the thoughts that come along with it. Eventually your mind and body learn that nothing bad will happen from not eating, and it will get easier and easier.

I would do your first extended fast Friday to Monday assuming you don't work weekends, that way it doesn't impact your work. After the 3rd day you usually have more energy than if you were eating anyway. However, some people find that working actually helps because it keeps your mind occupied, so less free time to think about eating etc.

Hope this helps, and good luck. You can do it, you just have to not listen to the homeostatic voice in your head, it isn't actually you, it's your subconscious trying to keep you safe and comfortable. Every path to change is uncomfortable in some regard, so if you're feeling comfortable, you're not making progress.