I am 31, m, 5'9" 170, with 17% bodyfat.
I am looking to do the 50/30/20 diet, as carbs make fat fast. Should I base my calories on my body weight or LBM? Right now my goal is gaining strength, and muscle, I am following a powerlifting program. If I had to guess, I would say that for every 1LB of muscle I have gained, I have gained 2lbs to 3lbs of fat. I am starting to get fat.

I have ultrasize, UMP, and just bought mass amino, and ultra40.

Base your calories on your bodyweight of 170 - start with about 2600 and don't get too technical as far as hitting exact on the ratios or calories. Limit your complex carbs to oatmeal with meal 1 and a complex carb at meal 3, but make sure you get in the calories and protein. That way you'll keep your strength and very possibly gain muscle while losing fat. Check out the Effective Beverly Diets in this section to get a good idea of meal structure.

Once again, make sure that you get the calories in as you start the diet while limiting complex carbs to meals 1 and 3.

i always base mine on lbm but ive been doing this for a while. that is muscle is more metabolically active compared to fat stores. if your eating to fuel fat you will not lose what you want to lose.

use rogers recommendation of the good kiw glycemic load long lasting carbs at meal 1 and 3