Honestly I’d start unfortunately with cutting sugar… Completely. Stop with any juices. Cola. You can however drink zero sugar sodas. Then stop with breakfast. If you Will he able to stick with it you can extend fast. Sugar Will make you more hungry. And carbs in general. But maybe don’t cut whole food groups in general. If you drink coffee with sugar. Start drinking without. If you stop eating around 18-20 it will be a good start.
This will be an unpopular opinion for this sub, but 17 is too young for fasting. Your body is still growing. Your best bet is to just try to cut out processed foods and empty calories. The Mediterranean diet is a really flexible starting point. Focus on progress not slip ups. You can reach your goals. Good luck.
I think a higher protein diet would work. I believe there are studies that say eating more protein and healthy fats helps to curb sugar cravings. For me personally, eating more sugar and (processed) carbs makes me want more sugar and carbs. I’d say on top of IF try to make your meals more nutritious with meal planning in a journal, a notes app, or a private document, But have a treat a couple times a week to satisfy the cravings. Good luck!