I cringe when someone says that they want to lose weight fast. That typically coinsides with a fast re-gain after the quick weight loss.
The turtle slow method of losing weight has typically proven to be the best way to go. The trick is to make healthy habits and KEEP those habits. You have to figure out where you struggle and where you are strong and keep re-evaluating what works and what doesn't. For example, I struggle with snacking in the evening after dinner. So, I have to really concentrate on that issue and keep from wandering into the kitchen at night. On the other hand, fasting comes realitively easy for me, so I implement that tool a few times per week and I don't even have to think about it. Sipping green tea in the evening helps to quell that snacking need in the evening.
I don't diet. I fast two to three days during the week. It's usually more of a "I'm too busy to eat" kind of thing, but it's also intentional as well. I really don't stress if I don't eat for a day, which is not something most people I know ever do. We weren't meant to be constantly fed with constant snacks and meals. I really don't do it for weight loss, but more of a cleansing type of thing. I also have more energy when I fast, which comes in handy. That said, I'm fit and healthy, but I could stand to lose 10 pounds.
Keto works, but it is tough to stick with. You still can lose weight just by going low carb, but you really have to watch the carbs closely. I used a food tracker the last time I went really low carb and it worked for me, but that's not something I would ever do long term. Still, while we practiced keto, we elimiinated milk and bread from our diets and (with rare exceptions) we haven't bought milk or bread in over a year. I also discovered some keto recipes that we still use even though we aren't as strict with our eats as we used to be. Moderation works best for me. I don't exclude anything from my diet, but I don't over indulge often either. Having a protein with veges for meals and making meals at home usually works best for us.