The best methods to prevent loss of LBM while dieting are hypertrophy based approaches. Personally, I keep my weight sessions to a 4 day body part split, hard and heavy, usually around 5-6 reps, lots of compound work (with some pre-exhaust as needed).
The weight loss will be the result of your diet, and cardio. Yes, the weight work will keep your BMR up, but it shouldn't really vary from what you're doing when trying to 'get big'.
For myself, I doubt a full body workout 3x a week would build, let alone even maintain my level of muscle mass.