The fundamental thing is calories in/calories out. Then you just need to find a strategy that helps you implement that that you can adhere to - keto, intermittent fasting, low fat, whatever. Track your calories under a few regimes and see which is easiest to stick to. People might argue one is better than the other, and that could well be true, but I think only at the individual level. What works for me might not work for you.

What worked for me (losing 14kg in 6 months) was only having two meals a day (lunch and dinner, breakfast was a coffee), and having the same (low calorie) meal for lunch every day.

Eating the same thing every day is not a bad idea: https://www.artofmanliness.com/health-fitness/health/the-gro...