Iv been doing a keto diet but feel like crap but have gotten great weight loss.... now i want to change it up a little bit.... something more simple

So i was reading about BMR dieting.. okay so my BMR is 2086..... so if i add my activity level as such to my BMR 2086 + 600(cal)... that gives me a 2686 which is my maintain caloric intake right?

So if i eat 500 calories less... and workout 5 days a week.... will i lose LBM this way and how long would you say it would take to lose 6-7% body fat?