the problem with 'counting calories' is that you are a human and not a bomb calorimeter. there is more to nutrition than energy. doing this will reduce body mass but in a way that affects muscle mass as well which is not good long term.

the best thing i can tell you is to try keto. most diets are memes, but there is interesting literature about ketosis and metabolic disease which is a large issue in weight gain. if nothing else, avoid processed food and cook yourself simple meals.